2. EL 6 ELS
  3. perl
  4. perlapi(1)

Scroll to navigation

PERLAPI(1) Perl Programmers Reference Guide PERLAPI(1)

NAME

perlapi - autogenerated documentation for the perl public API

DESCRIPTION

This file contains the documentation of the perl public API generated by embed.pl, specifically a listing of functions, macros, flags, and variables that may be used by extension writers. The interfaces of any functions that are not listed here are subject to change without notice. For this reason, blindly using functions listed in proto.h is to be avoided when writing extensions.

Note that all Perl API global variables must be referenced with the "PL_" prefix. Some macros are provided for compatibility with the older, unadorned names, but this support may be disabled in a future release.

Perl was originally written to handle US-ASCII only (that is characters whose ordinal numbers are in the range 0 - 127). And documentation and comments may still use the term ASCII, when sometimes in fact the entire range from 0 - 255 is meant.

Note that Perl can be compiled and run under EBCDIC (See perlebcdic) or ASCII. Most of the documentation (and even comments in the code) ignore the EBCDIC possibility. For almost all purposes the differences are transparent. As an example, under EBCDIC, instead of UTF-8, UTF-EBCDIC is used to encode Unicode strings, and so whenever this documentation refers to "utf8" (and variants of that name, including in function names), it also (essentially transparently) means "UTF-EBCDIC". But the ordinals of characters differ between ASCII, EBCDIC, and the UTF- encodings, and a string encoded in UTF-EBCDIC may occupy more bytes than in UTF-8.

Also, on some EBCDIC machines, functions that are documented as operating on US-ASCII (or Basic Latin in Unicode terminology) may in fact operate on all 256 characters in the EBCDIC range, not just the subset corresponding to US-ASCII.

The listing below is alphabetical, case insensitive.

"Gimme" Values

A backward-compatible version of "GIMME_V" which can only return "G_SCALAR" or "G_ARRAY"; in a void context, it returns "G_SCALAR". Deprecated. Use "GIMME_V" instead. 

        U32     GIMME
The XSUB-writer's equivalent to Perl's "wantarray". Returns "G_VOID", "G_SCALAR" or "G_ARRAY" for void, scalar or list context, respectively. 

        U32     GIMME_V
Used to indicate list context. See "GIMME_V", "GIMME" and perlcall.
Indicates that arguments returned from a callback should be discarded. See perlcall.
Used to force a Perl "eval" wrapper around a callback. See perlcall.
Indicates that no arguments are being sent to a callback. See perlcall.
Used to indicate scalar context. See "GIMME_V", "GIMME", and perlcall.
Used to indicate void context. See "GIMME_V" and perlcall.

Array Manipulation Functions

Same as "av_len()". Deprecated, use "av_len()" instead. 

        int     AvFILL(AV* av)
Clears an array, making it empty. Does not free the memory used by the array itself. 

        void    av_clear(AV *av)
Push an SV onto the end of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

NOTE: this function is experimental and may change or be removed without notice.

        void    av_create_and_push(AV **const avp, SV *const val)
Unshifts an SV onto the beginning of the array, creating the array if necessary. A small internal helper function to remove a commonly duplicated idiom.

NOTE: this function is experimental and may change or be removed without notice.

        SV**    av_create_and_unshift_one(AV **const avp, SV *const val)
Deletes the element indexed by "key" from the array. Returns the deleted element. If "flags" equals "G_DISCARD", the element is freed and null is returned. 

        SV*     av_delete(AV *av, I32 key, I32 flags)
Returns true if the element indexed by "key" has been initialized.

This relies on the fact that uninitialized array elements are set to &PL_sv_undef.

        bool    av_exists(AV *av, I32 key)
Pre-extend an array. The "key" is the index to which the array should be extended. 

        void    av_extend(AV *av, I32 key)
Returns the SV at the specified index in the array. The "key" is the index. If "lval" is set then the fetch will be part of a store. Check that the return value is non-null before dereferencing it to a "SV*".

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

        SV**    av_fetch(AV *av, I32 key, I32 lval)
Set the highest index in the array to the given number, equivalent to Perl's "$#array = $fill;".

The number of elements in the an array will be "fill + 1" after av_fill() returns. If the array was previously shorter then the additional elements appended are set to "PL_sv_undef". If the array was longer, then the excess elements are freed. "av_fill(av, -1)" is the same as "av_clear(av)".

        void    av_fill(AV *av, I32 fill)
Returns the highest index in the array. The number of elements in the array is "av_len(av) + 1". Returns -1 if the array is empty. 

        I32     av_len(const AV *av)
Creates a new AV and populates it with a list of SVs. The SVs are copied into the array, so they may be freed after the call to av_make. The new AV will have a reference count of 1. 

        AV*     av_make(I32 size, SV **strp)
Pops an SV off the end of the array. Returns &PL_sv_undef if the array is empty. 

        SV*     av_pop(AV *av)
Pushes an SV onto the end of the array. The array will grow automatically to accommodate the addition. Like "av_store", this takes ownership of one reference count. 

        void    av_push(AV *av, SV *val)
Shifts an SV off the beginning of the array. Returns &PL_sv_undef if the array is empty. 

        SV*     av_shift(AV *av)
Stores an SV in an array. The array index is specified as "key". The return value will be NULL if the operation failed or if the value did not need to be actually stored within the array (as in the case of tied arrays). Otherwise it can be dereferenced to get the original "SV*". Note that the caller is responsible for suitably incrementing the reference count of "val" before the call, and decrementing it if the function returned NULL.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied arrays.

        SV**    av_store(AV *av, I32 key, SV *val)
Undefines the array. Frees the memory used by the array itself. 

        void    av_undef(AV *av)
Unshift the given number of "undef" values onto the beginning of the array. The array will grow automatically to accommodate the addition. You must then use "av_store" to assign values to these new elements. 

        void    av_unshift(AV *av, I32 num)
Returns the AV of the specified Perl array. "flags" are passed to "gv_fetchpv". If "GV_ADD" is set and the Perl variable does not exist then it will be created. If "flags" is zero and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

        AV*     get_av(const char *name, I32 flags)
Creates a new AV. The reference count is set to 1. 

        AV*     newAV()
Sort an array. Here is an example: 

    sortsv(AvARRAY(av), av_len(av)+1, Perl_sv_cmp_locale);

Currently this always uses mergesort. See sortsv_flags for a more flexible routine.

        void    sortsv(SV** array, size_t num_elts, SVCOMPARE_t cmp)
Sort an array, with various options. 

        void    sortsv_flags(SV** array, size_t num_elts, SVCOMPARE_t cmp, U32 flags)

Callback Functions

Performs a callback to the specified Perl sub. See perlcall.

NOTE: the perl_ form of this function is deprecated.

        I32     call_argv(const char* sub_name, I32 flags, char** argv)
Performs a callback to the specified Perl method. The blessed object must be on the stack. See perlcall.

NOTE: the perl_ form of this function is deprecated.

        I32     call_method(const char* methname, I32 flags)
Performs a callback to the specified Perl sub. See perlcall.

NOTE: the perl_ form of this function is deprecated.

        I32     call_pv(const char* sub_name, I32 flags)
Performs a callback to the Perl sub whose name is in the SV. See perlcall.

NOTE: the perl_ form of this function is deprecated.

        I32     call_sv(SV* sv, VOL I32 flags)
Opening bracket on a callback. See "LEAVE" and perlcall. 

                ENTER;
Tells Perl to "eval" the given string and return an SV* result.

NOTE: the perl_ form of this function is deprecated.

        SV*     eval_pv(const char* p, I32 croak_on_error)
Tells Perl to "eval" the string in the SV.

NOTE: the perl_ form of this function is deprecated.

        I32     eval_sv(SV* sv, I32 flags)
Closing bracket for temporaries on a callback. See "SAVETMPS" and perlcall. 

                FREETMPS;
Closing bracket on a callback. See "ENTER" and perlcall. 

                LEAVE;
Opening bracket for temporaries on a callback. See "FREETMPS" and perlcall. 

                SAVETMPS;

Character classes

Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) alphanumeric character (including underscore) or digit. 

        bool    isALNUM(char ch)
Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) alphabetic character. 

        bool    isALPHA(char ch)
Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) digit. 

        bool    isDIGIT(char ch)
Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) lowercase character. 

        bool    isLOWER(char ch)
Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) whitespace. 

        bool    isSPACE(char ch)
Returns a boolean indicating whether the C "char" is a US-ASCII (Basic Latin) uppercase character. 

        bool    isUPPER(char ch)
Converts the specified character to lowercase. Characters outside the US-ASCII (Basic Latin) range are viewed as not having any case. 

        char    toLOWER(char ch)
Converts the specified character to uppercase. Characters outside the US-ASCII (Basic Latin) range are viewed as not having any case. 

        char    toUPPER(char ch)

Cloning an interpreter

Create and return a new interpreter by cloning the current one.

perl_clone takes these flags as parameters:

CLONEf_COPY_STACKS - is used to, well, copy the stacks also, without it we only clone the data and zero the stacks, with it we copy the stacks and the new perl interpreter is ready to run at the exact same point as the previous one. The pseudo-fork code uses COPY_STACKS while the threads->create doesn't.

CLONEf_KEEP_PTR_TABLE perl_clone keeps a ptr_table with the pointer of the old variable as a key and the new variable as a value, this allows it to check if something has been cloned and not clone it again but rather just use the value and increase the refcount. If KEEP_PTR_TABLE is not set then perl_clone will kill the ptr_table using the function "ptr_table_free(PL_ptr_table); PL_ptr_table = NULL;", reason to keep it around is if you want to dup some of your own variable who are outside the graph perl scans, example of this code is in threads.xs create

CLONEf_CLONE_HOST This is a win32 thing, it is ignored on unix, it tells perls win32host code (which is c++) to clone itself, this is needed on win32 if you want to run two threads at the same time, if you just want to do some stuff in a separate perl interpreter and then throw it away and return to the original one, you don't need to do anything.

        PerlInterpreter*        perl_clone(PerlInterpreter *proto_perl, UV flags)

CV Manipulation Functions

Returns the stash of the CV. 

        HV*     CvSTASH(CV* cv)
Uses "strlen" to get the length of "name", then calls "get_cvn_flags".

NOTE: the perl_ form of this function is deprecated.

        CV*     get_cv(const char* name, I32 flags)
Returns the CV of the specified Perl subroutine. "flags" are passed to "gv_fetchpvn_flags". If "GV_ADD" is set and the Perl subroutine does not exist then it will be declared (which has the same effect as saying "sub name;"). If "GV_ADD" is not set and the subroutine does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

        CV*     get_cvn_flags(const char* name, STRLEN len, I32 flags)

Embedding Functions

Clear out all the active components of a CV. This can happen either by an explicit "undef &foo", or by the reference count going to zero. In the former case, we keep the CvOUTSIDE pointer, so that any anonymous children can still follow the full lexical scope chain. 

        void    cv_undef(CV* cv)
Loads the module whose name is pointed to by the string part of name. Note that the actual module name, not its filename, should be given. Eg, "Foo::Bar" instead of "Foo/Bar.pm". flags can be any of PERL_LOADMOD_DENY, PERL_LOADMOD_NOIMPORT, or PERL_LOADMOD_IMPORT_OPS (or 0 for no flags). ver, if specified, provides version semantics similar to "use Foo::Bar VERSION". The optional trailing SV* arguments can be used to specify arguments to the module's import() method, similar to "use Foo::Bar VERSION LIST". They must be terminated with a final NULL pointer. Note that this list can only be omitted when the PERL_LOADMOD_NOIMPORT flag has been used. Otherwise at least a single NULL pointer to designate the default import list is required. 

        void    load_module(U32 flags, SV* name, SV* ver, ...)
Stub that provides thread hook for perl_destruct when there are no threads. 

        int     nothreadhook()
Allocates a new Perl interpreter. See perlembed. 

        PerlInterpreter*        perl_alloc()
Initializes a new Perl interpreter. See perlembed. 

        void    perl_construct(PerlInterpreter *my_perl)
Shuts down a Perl interpreter. See perlembed. 

        int     perl_destruct(PerlInterpreter *my_perl)
Releases a Perl interpreter. See perlembed. 

        void    perl_free(PerlInterpreter *my_perl)
Tells a Perl interpreter to parse a Perl script. See perlembed. 

        int     perl_parse(PerlInterpreter *my_perl, XSINIT_t xsinit, int argc, char** argv, char** env)
Tells a Perl interpreter to run. See perlembed. 

        int     perl_run(PerlInterpreter *my_perl)
Tells Perl to "require" the file named by the string argument. It is analogous to the Perl code "eval "require '$file'"". It's even implemented that way; consider using load_module instead.

NOTE: the perl_ form of this function is deprecated.

        void    require_pv(const char* pv)

Functions in file dump.c

Similar to 

  pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);

except that an additional "\0" will be appended to the string when len > cur and pv[cur] is "\0".

Note that the final string may be up to 7 chars longer than pvlim.

        char*   pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len, STRLEN pvlim)
Escapes at most the first "count" chars of pv and puts the results into dsv such that the size of the escaped string will not exceed "max" chars and will not contain any incomplete escape sequences.

If flags contains PERL_PV_ESCAPE_QUOTE then any double quotes in the string will also be escaped.

Normally the SV will be cleared before the escaped string is prepared, but when PERL_PV_ESCAPE_NOCLEAR is set this will not occur.

If PERL_PV_ESCAPE_UNI is set then the input string is treated as Unicode, if PERL_PV_ESCAPE_UNI_DETECT is set then the input string is scanned using "is_utf8_string()" to determine if it is Unicode.

If PERL_PV_ESCAPE_ALL is set then all input chars will be output using "\x01F1" style escapes, otherwise only chars above 255 will be escaped using this style, other non printable chars will use octal or common escaped patterns like "\n". If PERL_PV_ESCAPE_NOBACKSLASH then all chars below 255 will be treated as printable and will be output as literals.

If PERL_PV_ESCAPE_FIRSTCHAR is set then only the first char of the string will be escaped, regardles of max. If the string is utf8 and the chars value is >255 then it will be returned as a plain hex sequence. Thus the output will either be a single char, an octal escape sequence, a special escape like "\n" or a 3 or more digit hex value.

If PERL_PV_ESCAPE_RE is set then the escape char used will be a '%' and not a '\\'. This is because regexes very often contain backslashed sequences, whereas '%' is not a particularly common character in patterns.

Returns a pointer to the escaped text as held by dsv.

        char*   pv_escape(SV *dsv, char const * const str, const STRLEN count, const STRLEN max, STRLEN * const escaped, const U32 flags)
Converts a string into something presentable, handling escaping via pv_escape() and supporting quoting and ellipses.

If the PERL_PV_PRETTY_QUOTE flag is set then the result will be double quoted with any double quotes in the string escaped. Otherwise if the PERL_PV_PRETTY_LTGT flag is set then the result be wrapped in angle brackets.

If the PERL_PV_PRETTY_ELLIPSES flag is set and not all characters in string were output then an ellipsis "..." will be appended to the string. Note that this happens AFTER it has been quoted.

If start_color is non-null then it will be inserted after the opening quote (if there is one) but before the escaped text. If end_color is non-null then it will be inserted after the escaped text but before any quotes or ellipses.

Returns a pointer to the prettified text as held by dsv.

        char*   pv_pretty(SV *dsv, char const * const str, const STRLEN count, const STRLEN max, char const * const start_color, char const * const end_color, const U32 flags)

Functions in file mathoms.c

See gv_fetchmethod_autoload. 

        GV*     gv_fetchmethod(HV* stash, const char* name)
The engine implementing pack() Perl function. Note: parameters next_in_list and flags are not used. This call should not be used; use packlist instead. 

        void    pack_cat(SV *cat, const char *pat, const char *patend, SV **beglist, SV **endlist, SV ***next_in_list, U32 flags)
Return a pointer to the byte-encoded representation of the SV. May cause the SV to be downgraded from UTF-8 as a side-effect.

Usually accessed via the "SvPVbyte_nolen" macro.

        char*   sv_2pvbyte_nolen(SV* sv)
Return a pointer to the UTF-8-encoded representation of the SV. May cause the SV to be upgraded to UTF-8 as a side-effect.

Usually accessed via the "SvPVutf8_nolen" macro.

        char*   sv_2pvutf8_nolen(SV* sv)
Like "sv_2pv()", but doesn't return the length too. You should usually use the macro wrapper "SvPV_nolen(sv)" instead. char* sv_2pv_nolen(SV* sv)
Like "sv_catpvn", but also handles 'set' magic. 

        void    sv_catpvn_mg(SV *sv, const char *ptr, STRLEN len)
Like "sv_catsv", but also handles 'set' magic. 

        void    sv_catsv_mg(SV *dsv, SV *ssv)
Undo various types of fakery on an SV: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg. See also "sv_force_normal_flags". 

        void    sv_force_normal(SV *sv)
A private implementation of the "SvIVx" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        IV      sv_iv(SV* sv)
Dummy routine which "locks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

"Superseded" by sv_nosharing().

        void    sv_nolocking(SV *sv)
Dummy routine which "unlocks" an SV when there is no locking module present. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness.

"Superseded" by sv_nosharing().

        void    sv_nounlocking(SV *sv)
A private implementation of the "SvNVx" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        NV      sv_nv(SV* sv)
Use the "SvPV_nolen" macro instead 

        char*   sv_pv(SV *sv)
Use "SvPVbyte_nolen" instead. 

        char*   sv_pvbyte(SV *sv)
A private implementation of the "SvPVbyte" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        char*   sv_pvbyten(SV *sv, STRLEN *lp)
A private implementation of the "SvPV" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        char*   sv_pvn(SV *sv, STRLEN *lp)
Use the "SvPVutf8_nolen" macro instead 

        char*   sv_pvutf8(SV *sv)
A private implementation of the "SvPVutf8" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        char*   sv_pvutf8n(SV *sv, STRLEN *lp)
Taint an SV. Use "SvTAINTED_on" instead. void sv_taint(SV* sv)
Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of "newSVrv". This is "sv_unref_flags" with the "flag" being zero. See "SvROK_off". 

        void    sv_unref(SV* sv)
Tells an SV to use "ptr" to find its string value. Implemented by calling "sv_usepvn_flags" with "flags" of 0, hence does not handle 'set' magic. See "sv_usepvn_flags". 

        void    sv_usepvn(SV* sv, char* ptr, STRLEN len)
Like "sv_usepvn", but also handles 'set' magic. 

        void    sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)
A private implementation of the "SvUVx" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        UV      sv_uv(SV* sv)
The engine implementing unpack() Perl function. Note: parameters strbeg, new_s and ocnt are not used. This call should not be used, use unpackstring instead. 

        I32     unpack_str(const char *pat, const char *patend, const char *s, const char *strbeg, const char *strend, char **new_s, I32 ocnt, U32 flags)

Functions in file perl.h

Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters. 

        void    PERL_SYS_INIT(int argc, char** argv)
Provides system-specific tune up of the C runtime environment necessary to run Perl interpreters. This should be called only once, before creating any Perl interpreters. 

        void    PERL_SYS_INIT3(int argc, char** argv, char** env)
Provides system-specific clean up of the C runtime environment after running Perl interpreters. This should be called only once, after freeing any remaining Perl interpreters. 

        void    PERL_SYS_TERM()

Functions in file pp_ctl.c

Locate the CV corresponding to the currently executing sub or eval. If db_seqp is non_null, skip CVs that are in the DB package and populate *db_seqp with the cop sequence number at the point that the DB:: code was entered. (allows debuggers to eval in the scope of the breakpoint rather than in the scope of the debugger itself). 

        CV*     find_runcv(U32 *db_seqp)

Functions in file pp_pack.c

The engine implementing pack() Perl function. 

        void    packlist(SV *cat, const char *pat, const char *patend, SV **beglist, SV **endlist)
The engine implementing unpack() Perl function. "unpackstring" puts the extracted list items on the stack and returns the number of elements. Issue "PUTBACK" before and "SPAGAIN" after the call to this function. 

        I32     unpackstring(const char *pat, const char *patend, const char *s, const char *strend, U32 flags)

GV Functions

Return the SV from the GV. 

        SV*     GvSV(GV* gv)
If "gv" is a typeglob whose subroutine entry is a constant sub eligible for inlining, or "gv" is a placeholder reference that would be promoted to such a typeglob, then returns the value returned by the sub. Otherwise, returns NULL. 

        SV*     gv_const_sv(GV* gv)
Returns the glob with the given "name" and a defined subroutine or "NULL". The glob lives in the given "stash", or in the stashes accessible via @ISA and UNIVERSAL::.

The argument "level" should be either 0 or -1. If "level==0", as a side-effect creates a glob with the given "name" in the given "stash" which in the case of success contains an alias for the subroutine, and sets up caching info for this glob.

This function grants "SUPER" token as a postfix of the stash name. The GV returned from "gv_fetchmeth" may be a method cache entry, which is not visible to Perl code. So when calling "call_sv", you should not use the GV directly; instead, you should use the method's CV, which can be obtained from the GV with the "GvCV" macro.

        GV*     gv_fetchmeth(HV* stash, const char* name, STRLEN len, I32 level)
Returns the glob which contains the subroutine to call to invoke the method on the "stash". In fact in the presence of autoloading this may be the glob for "AUTOLOAD". In this case the corresponding variable $AUTOLOAD is already setup.

The third parameter of "gv_fetchmethod_autoload" determines whether AUTOLOAD lookup is performed if the given method is not present: non-zero means yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling "gv_fetchmethod" is equivalent to calling "gv_fetchmethod_autoload" with a non-zero "autoload" parameter.

These functions grant "SUPER" token as a prefix of the method name. Note that if you want to keep the returned glob for a long time, you need to check for it being "AUTOLOAD", since at the later time the call may load a different subroutine due to $AUTOLOAD changing its value. Use the glob created via a side effect to do this.

These functions have the same side-effects and as "gv_fetchmeth" with "level==0". "name" should be writable if contains ':' or ' ''. The warning against passing the GV returned by "gv_fetchmeth" to "call_sv" apply equally to these functions.

        GV*     gv_fetchmethod_autoload(HV* stash, const char* name, I32 autoload)
Same as gv_fetchmeth(), but looks for autoloaded subroutines too. Returns a glob for the subroutine.

For an autoloaded subroutine without a GV, will create a GV even if "level < 0". For an autoloaded subroutine without a stub, GvCV() of the result may be zero.

        GV*     gv_fetchmeth_autoload(HV* stash, const char* name, STRLEN len, I32 level)
Returns a pointer to the stash for a specified package. Uses "strlen" to determine the length of "name", then calls "gv_stashpvn()". 

        HV*     gv_stashpv(const char* name, I32 flags)
Returns a pointer to the stash for a specified package. The "namelen" parameter indicates the length of the "name", in bytes. "flags" is passed to "gv_fetchpvn_flags()", so if set to "GV_ADD" then the package will be created if it does not already exist. If the package does not exist and "flags" is 0 (or any other setting that does not create packages) then NULL is returned. 

        HV*     gv_stashpvn(const char* name, U32 namelen, I32 flags)
Like "gv_stashpvn", but takes a literal string instead of a string/length pair. 

        HV*     gv_stashpvs(const char* name, I32 create)
Returns a pointer to the stash for a specified package. See "gv_stashpvn". 

        HV*     gv_stashsv(SV* sv, I32 flags)

Handy Values

Null AV pointer.
Null character pointer.
Null CV pointer.
Null HV pointer.
Null SV pointer.

Hash Manipulation Functions

Returns the HV of the specified Perl hash. "flags" are passed to "gv_fetchpv". If "GV_ADD" is set and the Perl variable does not exist then it will be created. If "flags" is zero and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

        HV*     get_hv(const char *name, I32 flags)
This flag, used in the length slot of hash entries and magic structures, specifies the structure contains an "SV*" pointer where a "char*" pointer is to be expected. (For information only--not to be used).
Returns the computed hash stored in the hash entry. 

        U32     HeHASH(HE* he)
Returns the actual pointer stored in the key slot of the hash entry. The pointer may be either "char*" or "SV*", depending on the value of "HeKLEN()". Can be assigned to. The "HePV()" or "HeSVKEY()" macros are usually preferable for finding the value of a key. 

        void*   HeKEY(HE* he)
If this is negative, and amounts to "HEf_SVKEY", it indicates the entry holds an "SV*" key. Otherwise, holds the actual length of the key. Can be assigned to. The "HePV()" macro is usually preferable for finding key lengths. 

        STRLEN  HeKLEN(HE* he)
Returns the key slot of the hash entry as a "char*" value, doing any necessary dereferencing of possibly "SV*" keys. The length of the string is placed in "len" (this is a macro, so do not use &len). If you do not care about what the length of the key is, you may use the global variable "PL_na", though this is rather less efficient than using a local variable. Remember though, that hash keys in perl are free to contain embedded nulls, so using "strlen()" or similar is not a good way to find the length of hash keys. This is very similar to the "SvPV()" macro described elsewhere in this document. See also "HeUTF8".

If you are using "HePV" to get values to pass to "newSVpvn()" to create a new SV, you should consider using "newSVhek(HeKEY_hek(he))" as it is more efficient.

        char*   HePV(HE* he, STRLEN len)
Returns the key as an "SV*", or "NULL" if the hash entry does not contain an "SV*" key. 

        SV*     HeSVKEY(HE* he)
Returns the key as an "SV*". Will create and return a temporary mortal "SV*" if the hash entry contains only a "char*" key. 

        SV*     HeSVKEY_force(HE* he)
Sets the key to a given "SV*", taking care to set the appropriate flags to indicate the presence of an "SV*" key, and returns the same "SV*". 

        SV*     HeSVKEY_set(HE* he, SV* sv)
Returns whether the "char *" value returned by "HePV" is encoded in UTF-8, doing any necessary dereferencing of possibly "SV*" keys. The value returned will be 0 or non-0, not necessarily 1 (or even a value with any low bits set), so do not blindly assign this to a "bool" variable, as "bool" may be a typedef for "char". 

        char*   HeUTF8(HE* he, STRLEN len)
Returns the value slot (type "SV*") stored in the hash entry. 

        SV*     HeVAL(HE* he)
Returns the package name of a stash, or NULL if "stash" isn't a stash. See "SvSTASH", "CvSTASH". 

        char*   HvNAME(HV* stash)
Check that a hash is in an internally consistent state. 

        void    hv_assert(HV *hv)
Clears a hash, making it empty. 

        void    hv_clear(HV* hv)
Clears any placeholders from a hash. If a restricted hash has any of its keys marked as readonly and the key is subsequently deleted, the key is not actually deleted but is marked by assigning it a value of &PL_sv_placeholder. This tags it so it will be ignored by future operations such as iterating over the hash, but will still allow the hash to have a value reassigned to the key at some future point. This function clears any such placeholder keys from the hash. See Hash::Util::lock_keys() for an example of its use. 

        void    hv_clear_placeholders(HV *hv)
Deletes a key/value pair in the hash. The value SV is removed from the hash and returned to the caller. The "klen" is the length of the key. The "flags" value will normally be zero; if set to G_DISCARD then NULL will be returned. 

        SV*     hv_delete(HV *hv, const char *key, I32 klen, I32 flags)
Deletes a key/value pair in the hash. The value SV is removed from the hash and returned to the caller. The "flags" value will normally be zero; if set to G_DISCARD then NULL will be returned. "hash" can be a valid precomputed hash value, or 0 to ask for it to be computed. 

        SV*     hv_delete_ent(HV *hv, SV *keysv, I32 flags, U32 hash)
Returns a boolean indicating whether the specified hash key exists. The "klen" is the length of the key. 

        bool    hv_exists(HV *hv, const char *key, I32 klen)
Returns a boolean indicating whether the specified hash key exists. "hash" can be a valid precomputed hash value, or 0 to ask for it to be computed. 

        bool    hv_exists_ent(HV *hv, SV *keysv, U32 hash)
Returns the SV which corresponds to the specified key in the hash. The "klen" is the length of the key. If "lval" is set then the fetch will be part of a store. Check that the return value is non-null before dereferencing it to an "SV*".

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

        SV**    hv_fetch(HV *hv, const char *key, I32 klen, I32 lval)
Like "hv_fetch", but takes a literal string instead of a string/length pair. 

        SV**    hv_fetchs(HV* tb, const char* key, I32 lval)
Returns the hash entry which corresponds to the specified key in the hash. "hash" must be a valid precomputed hash number for the given "key", or 0 if you want the function to compute it. IF "lval" is set then the fetch will be part of a store. Make sure the return value is non-null before accessing it. The return value when "tb" is a tied hash is a pointer to a static location, so be sure to make a copy of the structure if you need to store it somewhere.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

        HE*     hv_fetch_ent(HV *hv, SV *keysv, I32 lval, U32 hash)
Prepares a starting point to traverse a hash table. Returns the number of keys in the hash (i.e. the same as "HvKEYS(tb)"). The return value is currently only meaningful for hashes without tie magic.

NOTE: Before version 5.004_65, "hv_iterinit" used to return the number of hash buckets that happen to be in use. If you still need that esoteric value, you can get it through the macro "HvFILL(tb)".

        I32     hv_iterinit(HV *hv)
Returns the key from the current position of the hash iterator. See "hv_iterinit". 

        char*   hv_iterkey(HE* entry, I32* retlen)
Returns the key as an "SV*" from the current position of the hash iterator. The return value will always be a mortal copy of the key. Also see "hv_iterinit". 

        SV*     hv_iterkeysv(HE* entry)
Returns entries from a hash iterator. See "hv_iterinit".

You may call "hv_delete" or "hv_delete_ent" on the hash entry that the iterator currently points to, without losing your place or invalidating your iterator. Note that in this case the current entry is deleted from the hash with your iterator holding the last reference to it. Your iterator is flagged to free the entry on the next call to "hv_iternext", so you must not discard your iterator immediately else the entry will leak - call "hv_iternext" to trigger the resource deallocation.

        HE*     hv_iternext(HV *hv)
Performs an "hv_iternext", "hv_iterkey", and "hv_iterval" in one operation. 

        SV*     hv_iternextsv(HV *hv, char **key, I32 *retlen)
Returns entries from a hash iterator. See "hv_iterinit" and "hv_iternext". The "flags" value will normally be zero; if HV_ITERNEXT_WANTPLACEHOLDERS is set the placeholders keys (for restricted hashes) will be returned in addition to normal keys. By default placeholders are automatically skipped over. Currently a placeholder is implemented with a value that is &Perl_sv_placeholder. Note that the implementation of placeholders and restricted hashes may change, and the implementation currently is insufficiently abstracted for any change to be tidy.

NOTE: this function is experimental and may change or be removed without notice.

        HE*     hv_iternext_flags(HV *hv, I32 flags)
Returns the value from the current position of the hash iterator. See "hv_iterkey". 

        SV*     hv_iterval(HV *hv, HE *entry)
Adds magic to a hash. See "sv_magic". 

        void    hv_magic(HV *hv, GV *gv, int how)
Evaluates the hash in scalar context and returns the result. Handles magic when the hash is tied. 

        SV*     hv_scalar(HV *hv)
Stores an SV in a hash. The hash key is specified as "key" and "klen" is the length of the key. The "hash" parameter is the precomputed hash value; if it is zero then Perl will compute it. The return value will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise it can be dereferenced to get the original "SV*". Note that the caller is responsible for suitably incrementing the reference count of "val" before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store takes ownership of one reference to "val". This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

        SV**    hv_store(HV *hv, const char *key, I32 klen, SV *val, U32 hash)
Like "hv_store", but takes a literal string instead of a string/length pair and omits the hash parameter. 

        SV**    hv_stores(HV* tb, const char* key, NULLOK SV* val)
Stores "val" in a hash. The hash key is specified as "key". The "hash" parameter is the precomputed hash value; if it is zero then Perl will compute it. The return value is the new hash entry so created. It will be NULL if the operation failed or if the value did not need to be actually stored within the hash (as in the case of tied hashes). Otherwise the contents of the return value can be accessed using the "He?" macros described here. Note that the caller is responsible for suitably incrementing the reference count of "val" before the call, and decrementing it if the function returned NULL. Effectively a successful hv_store_ent takes ownership of one reference to "val". This is usually what you want; a newly created SV has a reference count of one, so if all your code does is create SVs then store them in a hash, hv_store will own the only reference to the new SV, and your code doesn't need to do anything further to tidy up. Note that hv_store_ent only reads the "key"; unlike "val" it does not take ownership of it, so maintaining the correct reference count on "key" is entirely the caller's responsibility. hv_store is not implemented as a call to hv_store_ent, and does not create a temporary SV for the key, so if your key data is not already in SV form then use hv_store in preference to hv_store_ent.

See "Understanding the Magic of Tied Hashes and Arrays" in perlguts for more information on how to use this function on tied hashes.

        HE*     hv_store_ent(HV *hv, SV *key, SV *val, U32 hash)
Undefines the hash. 

        void    hv_undef(HV *hv)
Creates a new HV. The reference count is set to 1. 

        HV*     newHV()

Magical Functions

Clear something magical that the SV represents. See "sv_magic". 

        int     mg_clear(SV* sv)
Copies the magic from one SV to another. See "sv_magic". 

        int     mg_copy(SV *sv, SV *nsv, const char *key, I32 klen)
Finds the magic pointer for type matching the SV. See "sv_magic". 

        MAGIC*  mg_find(const SV* sv, int type)
Free any magic storage used by the SV. See "sv_magic". 

        int     mg_free(SV* sv)
Do magic after a value is retrieved from the SV. See "sv_magic". 

        int     mg_get(SV* sv)
Report on the SV's length. See "sv_magic". 

        U32     mg_length(SV* sv)
Turns on the magical status of an SV. See "sv_magic". 

        void    mg_magical(SV* sv)
Do magic after a value is assigned to the SV. See "sv_magic". 

        int     mg_set(SV* sv)
Invokes "mg_get" on an SV if it has 'get' magic. This macro evaluates its argument more than once. 

        void    SvGETMAGIC(SV* sv)
Arranges for a mutual exclusion lock to be obtained on sv if a suitable module has been loaded. 

        void    SvLOCK(SV* sv)
Invokes "mg_set" on an SV if it has 'set' magic. This macro evaluates its argument more than once. 

        void    SvSETMAGIC(SV* sv)
Like "SvSetSV", but does any set magic required afterwards. 

        void    SvSetMagicSV(SV* dsb, SV* ssv)
Like "SvSetSV_nosteal", but does any set magic required afterwards. 

        void    SvSetMagicSV_nosteal(SV* dsv, SV* ssv)
Calls "sv_setsv" if dsv is not the same as ssv. May evaluate arguments more than once. 

        void    SvSetSV(SV* dsb, SV* ssv)
Calls a non-destructive version of "sv_setsv" if dsv is not the same as ssv. May evaluate arguments more than once. 

        void    SvSetSV_nosteal(SV* dsv, SV* ssv)
Arranges for sv to be shared between threads if a suitable module has been loaded. 

        void    SvSHARE(SV* sv)
Releases a mutual exclusion lock on sv if a suitable module has been loaded. 

        void    SvUNLOCK(SV* sv)

Memory Management

The XSUB-writer's interface to the C "memcpy" function. The "src" is the source, "dest" is the destination, "nitems" is the number of items, and "type" is the type. May fail on overlapping copies. See also "Move". 

        void    Copy(void* src, void* dest, int nitems, type)
Like "Copy" but returns dest. Useful for encouraging compilers to tail-call optimise. 

        void *  CopyD(void* src, void* dest, int nitems, type)
The XSUB-writer's interface to the C "memmove" function. The "src" is the source, "dest" is the destination, "nitems" is the number of items, and "type" is the type. Can do overlapping moves. See also "Copy". 

        void    Move(void* src, void* dest, int nitems, type)
Like "Move" but returns dest. Useful for encouraging compilers to tail-call optimise. 

        void *  MoveD(void* src, void* dest, int nitems, type)
The XSUB-writer's interface to the C "malloc" function.

In 5.9.3, Newx() and friends replace the older New() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhack). The older API is still there for use in XS modules supporting older perls.

        void    Newx(void* ptr, int nitems, type)
The XSUB-writer's interface to the C "malloc" function, with cast. See also "Newx". 

        void    Newxc(void* ptr, int nitems, type, cast)
The XSUB-writer's interface to the C "malloc" function. The allocated memory is zeroed with "memzero". See also "Newx". 

        void    Newxz(void* ptr, int nitems, type)
PoisonWith(0xEF) for catching access to freed memory. 

        void    Poison(void* dest, int nitems, type)
PoisonWith(0xEF) for catching access to freed memory. 

        void    PoisonFree(void* dest, int nitems, type)
PoisonWith(0xAB) for catching access to allocated but uninitialized memory. 

        void    PoisonNew(void* dest, int nitems, type)
Fill up memory with a byte pattern (a byte repeated over and over again) that hopefully catches attempts to access uninitialized memory. 

        void    PoisonWith(void* dest, int nitems, type, U8 byte)
The XSUB-writer's interface to the C "realloc" function. 

        void    Renew(void* ptr, int nitems, type)
The XSUB-writer's interface to the C "realloc" function, with cast. 

        void    Renewc(void* ptr, int nitems, type, cast)
The XSUB-writer's interface to the C "free" function. 

        void    Safefree(void* ptr)
Perl's version of "strdup()". Returns a pointer to a newly allocated string which is a duplicate of "pv". The size of the string is determined by "strlen()". The memory allocated for the new string can be freed with the "Safefree()" function. 

        char*   savepv(const char* pv)
Perl's version of what "strndup()" would be if it existed. Returns a pointer to a newly allocated string which is a duplicate of the first "len" bytes from "pv", plus a trailing NUL byte. The memory allocated for the new string can be freed with the "Safefree()" function. 

        char*   savepvn(const char* pv, I32 len)
Like "savepvn", but takes a literal string instead of a string/length pair. 

        char*   savepvs(const char* s)
A version of "savepv()" which allocates the duplicate string in memory which is shared between threads. 

        char*   savesharedpv(const char* pv)
A version of "savepvn()" which allocates the duplicate string in memory which is shared between threads. (With the specific difference that a NULL pointer is not acceptable) 

        char*   savesharedpvn(const char *const pv, const STRLEN len)
A version of "savepv()"/"savepvn()" which gets the string to duplicate from the passed in SV using "SvPV()" 

        char*   savesvpv(SV* sv)
This is an architecture-independent macro to copy one structure to another. 

        void    StructCopy(type src, type dest, type)
The XSUB-writer's interface to the C "memzero" function. The "dest" is the destination, "nitems" is the number of items, and "type" is the type. 

        void    Zero(void* dest, int nitems, type)
Like "Zero" but returns dest. Useful for encouraging compilers to tail-call optimise. 

        void *  ZeroD(void* dest, int nitems, type)

Miscellaneous Functions

Analyses the string in order to make fast searches on it using fbm_instr() -- the Boyer-Moore algorithm. 

        void    fbm_compile(SV* sv, U32 flags)
Returns the location of the SV in the string delimited by "str" and "strend". It returns "NULL" if the string can't be found. The "sv" does not have to be fbm_compiled, but the search will not be as fast then. 

        char*   fbm_instr(unsigned char* big, unsigned char* bigend, SV* littlestr, U32 flags)
Takes a sprintf-style format pattern and conventional (non-SV) arguments and returns the formatted string. 

    (char *) Perl_form(pTHX_ const char* pat, ...)

can be used any place a string (char *) is required:

    char * s = Perl_form("%d.%d",major,minor);

Uses a single private buffer so if you want to format several strings you must explicitly copy the earlier strings away (and free the copies when you are done).

        char*   form(const char* pat, ...)
Fill the sv with current working directory 

        int     getcwd_sv(SV* sv)
The C library "snprintf" functionality, if available and standards-compliant (uses "vsnprintf", actually). However, if the "vsnprintf" is not available, will unfortunately use the unsafe "vsprintf" which can overrun the buffer (there is an overrun check, but that may be too late). Consider using "sv_vcatpvf" instead, or getting "vsnprintf". 

        int     my_snprintf(char *buffer, const Size_t len, const char *format, ...)
The C library "sprintf", wrapped if necessary, to ensure that it will return the length of the string written to the buffer. Only rare pre-ANSI systems need the wrapper function - usually this is a direct call to "sprintf". 

        int     my_sprintf(char *buffer, const char *pat, ...)
The C library "vsnprintf" if available and standards-compliant. However, if if the "vsnprintf" is not available, will unfortunately use the unsafe "vsprintf" which can overrun the buffer (there is an overrun check, but that may be too late). Consider using "sv_vcatpvf" instead, or getting "vsnprintf". 

        int     my_vsnprintf(char *buffer, const Size_t len, const char *format, va_list ap)
Returns a new version object based on the passed in SV: 

    SV *sv = new_version(SV *ver);

Does not alter the passed in ver SV. See "upg_version" if you want to upgrade the SV.

        SV*     new_version(SV *ver)
Returns a pointer to the next character after the parsed version string, as well as upgrading the passed in SV to an RV.

Function must be called with an already existing SV like

    sv = newSV(0);
    s = scan_version(s, SV *sv, bool qv);

Performs some preprocessing to the string to ensure that it has the correct characteristics of a version. Flags the object if it contains an underscore (which denotes this is an alpha version). The boolean qv denotes that the version should be interpreted as if it had multiple decimals, even if it doesn't.

        const char*     scan_version(const char *s, SV *rv, bool qv)
Test two strings to see if they are equal. Returns true or false. 

        bool    strEQ(char* s1, char* s2)
Test two strings to see if the first, "s1", is greater than or equal to the second, "s2". Returns true or false. 

        bool    strGE(char* s1, char* s2)
Test two strings to see if the first, "s1", is greater than the second, "s2". Returns true or false. 

        bool    strGT(char* s1, char* s2)
Test two strings to see if the first, "s1", is less than or equal to the second, "s2". Returns true or false. 

        bool    strLE(char* s1, char* s2)
Test two strings to see if the first, "s1", is less than the second, "s2". Returns true or false. 

        bool    strLT(char* s1, char* s2)
Test two strings to see if they are different. Returns true or false. 

        bool    strNE(char* s1, char* s2)
Test two strings to see if they are equal. The "len" parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for "strncmp"). 

        bool    strnEQ(char* s1, char* s2, STRLEN len)
Test two strings to see if they are different. The "len" parameter indicates the number of bytes to compare. Returns true or false. (A wrapper for "strncmp"). 

        bool    strnNE(char* s1, char* s2, STRLEN len)
Dummy routine which reports that object can be destroyed when there is no sharing module present. It ignores its single SV argument, and returns 'true'. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness. 

        bool    sv_destroyable(SV *sv)
Dummy routine which "shares" an SV when there is no sharing module present. Or "locks" it. Or "unlocks" it. In other words, ignores its single SV argument. Exists to avoid test for a NULL function pointer and because it could potentially warn under some level of strict-ness. 

        void    sv_nosharing(SV *sv)
In-place upgrade of the supplied SV to a version object. 

    SV *sv = upg_version(SV *sv, bool qv);

Returns a pointer to the upgraded SV. Set the boolean qv if you want to force this SV to be interpreted as an "extended" version.

        SV*     upg_version(SV *ver, bool qv)
Version object aware cmp. Both operands must already have been converted into version objects. 

        int     vcmp(SV *lhv, SV *rhv)
Accepts a version object and returns the normalized string representation. Call like: 

    sv = vnormal(rv);

NOTE: you can pass either the object directly or the SV contained within the RV.

        SV*     vnormal(SV *vs)
Accepts a version object and returns the normalized floating point representation. Call like: 

    sv = vnumify(rv);

NOTE: you can pass either the object directly or the SV contained within the RV.

        SV*     vnumify(SV *vs)
In order to maintain maximum compatibility with earlier versions of Perl, this function will return either the floating point notation or the multiple dotted notation, depending on whether the original version contained 1 or more dots, respectively 

        SV*     vstringify(SV *vs)
Validates that the SV contains a valid version object. 

    bool vverify(SV *vobj);

Note that it only confirms the bare minimum structure (so as not to get confused by derived classes which may contain additional hash entries):

        bool    vverify(SV *vs)

MRO Functions

Returns either "mro_get_linear_isa_c3" or "mro_get_linear_isa_dfs" for the given stash, dependant upon which MRO is in effect for that stash. The return value is a read-only AV*.

You are responsible for "SvREFCNT_inc()" on the return value if you plan to store it anywhere semi-permanently (otherwise it might be deleted out from under you the next time the cache is invalidated).

        AV*     mro_get_linear_isa(HV* stash)
Invalidates method caching on any child classes of the given stash, so that they might notice the changes in this one.

Ideally, all instances of "PL_sub_generation++" in perl source outside of "mro.c" should be replaced by calls to this.

Perl automatically handles most of the common ways a method might be redefined. However, there are a few ways you could change a method in a stash without the cache code noticing, in which case you need to call this method afterwards:

1) Directly manipulating the stash HV entries from XS code.

2) Assigning a reference to a readonly scalar constant into a stash entry in order to create a constant subroutine (like constant.pm does).

This same method is available from pure perl via, "mro::method_changed_in(classname)".

        void    mro_method_changed_in(HV* stash)

Multicall Functions

Declare local variables for a multicall. See "Lightweight Callbacks" in perlcall. 

                dMULTICALL;
Make a lightweight callback. See "Lightweight Callbacks" in perlcall. 

                MULTICALL;
Closing bracket for a lightweight callback. See "Lightweight Callbacks" in perlcall. 

                POP_MULTICALL;
Opening bracket for a lightweight callback. See "Lightweight Callbacks" in perlcall. 

                PUSH_MULTICALL;

Numeric functions

converts a string representing a binary number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or the first invalid character. Unless "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *flags gives output flags.

If the value is <= "UV_MAX" it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX "grok_bin" returns UV_MAX, sets "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

The binary number may optionally be prefixed with "0b" or "b" unless "PERL_SCAN_DISALLOW_PREFIX" is set in *flags on entry. If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then the binary number may use '_' characters to separate digits.

        UV      grok_bin(const char* start, STRLEN* len_p, I32* flags, NV *result)
converts a string representing a hex number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or the first invalid character. Unless "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX "grok_hex" returns UV_MAX, sets "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

The hex number may optionally be prefixed with "0x" or "x" unless "PERL_SCAN_DISALLOW_PREFIX" is set in *flags on entry. If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then the hex number may use '_' characters to separate digits.

        UV      grok_hex(const char* start, STRLEN* len_p, I32* flags, NV *result)
Recognise (or not) a number. The type of the number is returned (0 if unrecognised), otherwise it is a bit-ORed combination of IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT, IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).

If the value of the number can fit an in UV, it is returned in the *valuep IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV will never be set unless *valuep is valid, but *valuep may have been assigned to during processing even though IS_NUMBER_IN_UV is not set on return. If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when valuep is non-NULL, but no actual assignment (or SEGV) will occur.

IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were seen (in which case *valuep gives the true value truncated to an integer), and IS_NUMBER_NEG if the number is negative (in which case *valuep holds the absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the number is larger than a UV.

        int     grok_number(const char *pv, STRLEN len, UV *valuep)
Scan and skip for a numeric decimal separator (radix). 

        bool    grok_numeric_radix(const char **sp, const char *send)
converts a string representing an octal number to numeric form.

On entry start and *len give the string to scan, *flags gives conversion flags, and result should be NULL or a pointer to an NV. The scan stops at the end of the string, or the first invalid character. Unless "PERL_SCAN_SILENT_ILLDIGIT" is set in *flags, encountering an invalid character will also trigger a warning. On return *len is set to the length of the scanned string, and *flags gives output flags.

If the value is <= UV_MAX it is returned as a UV, the output flags are clear, and nothing is written to *result. If the value is > UV_MAX "grok_oct" returns UV_MAX, sets "PERL_SCAN_GREATER_THAN_UV_MAX" in the output flags, and writes the value to *result (or the value is discarded if result is NULL).

If "PERL_SCAN_ALLOW_UNDERSCORES" is set in *flags then the octal number may use '_' characters to separate digits.

        UV      grok_oct(const char* start, STRLEN* len_p, I32* flags, NV *result)
Return a non-zero integer if the sign bit on an NV is set, and 0 if it is not.

If Configure detects this system has a signbit() that will work with our NVs, then we just use it via the #define in perl.h. Otherwise, fall back on this implementation. As a first pass, this gets everything right except -0.0. Alas, catching -0.0 is the main use for this function, so this is not too helpful yet. Still, at least we have the scaffolding in place to support other systems, should that prove useful.

Configure notes: This function is called 'Perl_signbit' instead of a plain 'signbit' because it is easy to imagine a system having a signbit() function or macro that doesn't happen to work with our particular choice of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect the standard system headers to be happy. Also, this is a no-context function (no pTHX_) because Perl_signbit() is usually re-#defined in perl.h as a simple macro call to the system's signbit(). Users should just always call Perl_signbit().

NOTE: this function is experimental and may change or be removed without notice.

        int     Perl_signbit(NV f)
For backwards compatibility. Use "grok_bin" instead. 

        NV      scan_bin(const char* start, STRLEN len, STRLEN* retlen)
For backwards compatibility. Use "grok_hex" instead. 

        NV      scan_hex(const char* start, STRLEN len, STRLEN* retlen)
For backwards compatibility. Use "grok_oct" instead. 

        NV      scan_oct(const char* start, STRLEN len, STRLEN* retlen)

Optree Manipulation Functions

If "cv" is a constant sub eligible for inlining. returns the constant value returned by the sub. Otherwise, returns NULL.

Constant subs can be created with "newCONSTSUB" or as described in "Constant Functions" in perlsub.

        SV*     cv_const_sv(CV* cv)
Creates a constant sub equivalent to Perl "sub FOO () { 123 }" which is eligible for inlining at compile-time. 

        CV*     newCONSTSUB(HV* stash, const char* name, SV* sv)
Used by "xsubpp" to hook up XSUBs as Perl subs. filename needs to be static storage, as it is used directly as CvFILE(), without a copy being made.

Pad Data Structures

Get the value at offset po in the current pad. Use macro PAD_SV instead of calling this function directly. 

        SV*     pad_sv(PADOFFSET po)

Per-Interpreter Variables

"PL_modglobal" is a general purpose, interpreter global HV for use by extensions that need to keep information on a per-interpreter basis. In a pinch, it can also be used as a symbol table for extensions to share data among each other. It is a good idea to use keys prefixed by the package name of the extension that owns the data. 

        HV*     PL_modglobal
A convenience variable which is typically used with "SvPV" when one doesn't care about the length of the string. It is usually more efficient to either declare a local variable and use that instead or to use the "SvPV_nolen" macro. 

        STRLEN  PL_na
This is the "false" SV. See "PL_sv_yes". Always refer to this as &PL_sv_no. 

        SV      PL_sv_no
This is the "undef" SV. Always refer to this as &PL_sv_undef. 

        SV      PL_sv_undef
This is the "true" SV. See "PL_sv_no". Always refer to this as &PL_sv_yes. 

        SV      PL_sv_yes

REGEXP Functions

Convenience macro to get the REGEXP from a SV. This is approximately equivalent to the following snippet: 

    if (SvMAGICAL(sv))
        mg_get(sv);
    if (SvROK(sv) &&
        (tmpsv = (SV*)SvRV(sv)) &&
        SvTYPE(tmpsv) == SVt_PVMG &&
        (tmpmg = mg_find(tmpsv, PERL_MAGIC_qr)))
    {
        return (REGEXP *)tmpmg->mg_obj;
    }

NULL will be returned if a REGEXP* is not found.

        REGEXP *        SvRX(SV *sv)
Returns a boolean indicating whether the SV contains qr magic (PERL_MAGIC_qr).

If you want to do something with the REGEXP* later use SvRX instead and check for NULL.

        bool    SvRXOK(SV* sv)

Simple Exception Handling Macros

Set up necessary local variables for exception handling. See "Exception Handling" in perlguts. 

                dXCPT;
Introduces a catch block. See "Exception Handling" in perlguts.
Rethrows a previously caught exception. See "Exception Handling" in perlguts. 

                XCPT_RETHROW;
Ends a try block. See "Exception Handling" in perlguts.
Starts a try block. See "Exception Handling" in perlguts.

Stack Manipulation Macros

Declare a stack marker variable, "mark", for the XSUB. See "MARK" and "dORIGMARK". 

                dMARK;
Saves the original stack mark for the XSUB. See "ORIGMARK". 

                dORIGMARK;
Declares a local copy of perl's stack pointer for the XSUB, available via the "SP" macro. See "SP". 

                dSP;
Used to extend the argument stack for an XSUB's return values. Once used, guarantees that there is room for at least "nitems" to be pushed onto the stack. 

        void    EXTEND(SP, int nitems)
Stack marker variable for the XSUB. See "dMARK".
Push an integer onto the stack. The stack must have room for this element. Does not use "TARG". See also "PUSHi", "mXPUSHi" and "XPUSHi". 

        void    mPUSHi(IV iv)
Push a double onto the stack. The stack must have room for this element. Does not use "TARG". See also "PUSHn", "mXPUSHn" and "XPUSHn". 

        void    mPUSHn(NV nv)
Push a string onto the stack. The stack must have room for this element. The "len" indicates the length of the string. Does not use "TARG". See also "PUSHp", "mXPUSHp" and "XPUSHp". 

        void    mPUSHp(char* str, STRLEN len)
Push an SV onto the stack and mortalizes the SV. The stack must have room for this element. Does not use "TARG". See also "PUSHs" and "mXPUSHs". 

        void    mPUSHs(SV* sv)
Push an unsigned integer onto the stack. The stack must have room for this element. Does not use "TARG". See also "PUSHu", "mXPUSHu" and "XPUSHu". 

        void    mPUSHu(UV uv)
Push an integer onto the stack, extending the stack if necessary. Does not use "TARG". See also "XPUSHi", "mPUSHi" and "PUSHi". 

        void    mXPUSHi(IV iv)
Push a double onto the stack, extending the stack if necessary. Does not use "TARG". See also "XPUSHn", "mPUSHn" and "PUSHn". 

        void    mXPUSHn(NV nv)
Push a string onto the stack, extending the stack if necessary. The "len" indicates the length of the string. Does not use "TARG". See also "XPUSHp", "mPUSHp" and "PUSHp". 

        void    mXPUSHp(char* str, STRLEN len)
Push an SV onto the stack, extending the stack if necessary and mortalizes the SV. Does not use "TARG". See also "XPUSHs" and "mPUSHs". 

        void    mXPUSHs(SV* sv)
Push an unsigned integer onto the stack, extending the stack if necessary. Does not use "TARG". See also "XPUSHu", "mPUSHu" and "PUSHu". 

        void    mXPUSHu(UV uv)
The original stack mark for the XSUB. See "dORIGMARK".
Pops an integer off the stack. 

        IV      POPi
Pops a long off the stack. 

        long    POPl
Pops a double off the stack. 

        NV      POPn
Pops a string off the stack. Deprecated. New code should use POPpx. 

        char*   POPp
Pops a string off the stack which must consist of bytes i.e. characters < 256. 

        char*   POPpbytex
Pops a string off the stack. 

        char*   POPpx
Pops an SV off the stack. 

        SV*     POPs
Push an integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mPUSHi" instead. See also "XPUSHi" and "mXPUSHi". 

        void    PUSHi(IV iv)
Opening bracket for arguments on a callback. See "PUTBACK" and perlcall. 

        void    PUSHMARK(SP)
Push a new mortal SV onto the stack. The stack must have room for this element. Does not use "TARG". See also "PUSHs", "XPUSHmortal" and "XPUSHs". 

        void    PUSHmortal()
Push a double onto the stack. The stack must have room for this element. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mPUSHn" instead. See also "XPUSHn" and "mXPUSHn". 

        void    PUSHn(NV nv)
Push a string onto the stack. The stack must have room for this element. The "len" indicates the length of the string. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mPUSHp" instead. See also "XPUSHp" and "mXPUSHp". 

        void    PUSHp(char* str, STRLEN len)
Push an SV onto the stack. The stack must have room for this element. Does not handle 'set' magic. Does not use "TARG". See also "PUSHmortal", "XPUSHs" and "XPUSHmortal". 

        void    PUSHs(SV* sv)
Push an unsigned integer onto the stack. The stack must have room for this element. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mPUSHu" instead. See also "XPUSHu" and "mXPUSHu". 

        void    PUSHu(UV uv)
Closing bracket for XSUB arguments. This is usually handled by "xsubpp". See "PUSHMARK" and perlcall for other uses. 

                PUTBACK;
Stack pointer. This is usually handled by "xsubpp". See "dSP" and "SPAGAIN".
Refetch the stack pointer. Used after a callback. See perlcall. 

                SPAGAIN;
Push an integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHi" instead. See also "PUSHi" and "mPUSHi". 

        void    XPUSHi(IV iv)
Push a new mortal SV onto the stack, extending the stack if necessary. Does not use "TARG". See also "XPUSHs", "PUSHmortal" and "PUSHs". 

        void    XPUSHmortal()
Push a double onto the stack, extending the stack if necessary. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHn" instead. See also "PUSHn" and "mPUSHn". 

        void    XPUSHn(NV nv)
Push a string onto the stack, extending the stack if necessary. The "len" indicates the length of the string. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHp" instead. See also "PUSHp" and "mPUSHp". 

        void    XPUSHp(char* str, STRLEN len)
Push an SV onto the stack, extending the stack if necessary. Does not handle 'set' magic. Does not use "TARG". See also "XPUSHmortal", "PUSHs" and "PUSHmortal". 

        void    XPUSHs(SV* sv)
Push an unsigned integer onto the stack, extending the stack if necessary. Handles 'set' magic. Uses "TARG", so "dTARGET" or "dXSTARG" should be called to declare it. Do not call multiple "TARG"-oriented macros to return lists from XSUB's - see "mXPUSHu" instead. See also "PUSHu" and "mPUSHu". 

        void    XPUSHu(UV uv)
Return from XSUB, indicating number of items on the stack. This is usually handled by "xsubpp". 

        void    XSRETURN(int nitems)
Return an empty list from an XSUB immediately. 

                XSRETURN_EMPTY;
Return an integer from an XSUB immediately. Uses "XST_mIV". 

        void    XSRETURN_IV(IV iv)
Return &PL_sv_no from an XSUB immediately. Uses "XST_mNO". 

                XSRETURN_NO;
Return a double from an XSUB immediately. Uses "XST_mNV". 

        void    XSRETURN_NV(NV nv)
Return a copy of a string from an XSUB immediately. Uses "XST_mPV". 

        void    XSRETURN_PV(char* str)
Return &PL_sv_undef from an XSUB immediately. Uses "XST_mUNDEF". 

                XSRETURN_UNDEF;
Return an integer from an XSUB immediately. Uses "XST_mUV". 

        void    XSRETURN_UV(IV uv)
Return &PL_sv_yes from an XSUB immediately. Uses "XST_mYES". 

                XSRETURN_YES;
Place an integer into the specified position "pos" on the stack. The value is stored in a new mortal SV. 

        void    XST_mIV(int pos, IV iv)
Place &PL_sv_no into the specified position "pos" on the stack. 

        void    XST_mNO(int pos)
Place a double into the specified position "pos" on the stack. The value is stored in a new mortal SV. 

        void    XST_mNV(int pos, NV nv)
Place a copy of a string into the specified position "pos" on the stack. The value is stored in a new mortal SV. 

        void    XST_mPV(int pos, char* str)
Place &PL_sv_undef into the specified position "pos" on the stack. 

        void    XST_mUNDEF(int pos)
Place &PL_sv_yes into the specified position "pos" on the stack. 

        void    XST_mYES(int pos)

SV Flags

An enum of flags for Perl types. These are found in the file sv.h in the "svtype" enum. Test these flags with the "SvTYPE" macro.
Integer type flag for scalars. See "svtype".
Double type flag for scalars. See "svtype".
Pointer type flag for scalars. See "svtype".
Type flag for arrays. See "svtype".
Type flag for code refs. See "svtype".
Type flag for hashes. See "svtype".
Type flag for blessed scalars. See "svtype".

SV Manipulation Functions

A specialised variant of "croak()" for emitting the usage message for xsubs 

    croak_xs_usage(cv, "eee_yow");

works out the package name and subroutine name from "cv", and then calls "croak()". Hence if "cv" is &ouch::awk, it would call "croak" as:

    Perl_croak(aTHX_ "Usage %s::%s(%s)", "ouch" "awk", "eee_yow");
        void    croak_xs_usage(const CV *const cv, const char *const params)
Returns the SV of the specified Perl scalar. "flags" are passed to "gv_fetchpv". If "GV_ADD" is set and the Perl variable does not exist then it will be created. If "flags" is zero and the variable does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

        SV*     get_sv(const char *name, I32 flags)
Creates an RV wrapper for an SV. The reference count for the original SV is incremented. 

        SV*     newRV_inc(SV* sv)
Creates a new SV and copies a string into it. If utf8 is true, calls "SvUTF8_on" on the new SV. Implemented as a wrapper around "newSVpvn_flags". 

        SV*     newSVpvn_utf8(NULLOK const char* s, STRLEN len, U32 utf8)
Returns the length of the string which is in the SV. See "SvLEN". 

        STRLEN  SvCUR(SV* sv)
Set the current length of the string which is in the SV. See "SvCUR" and "SvIV_set". 

        void    SvCUR_set(SV* sv, STRLEN len)
Returns a pointer to the last character in the string which is in the SV. See "SvCUR". Access the character as *(SvEND(sv)). 

        char*   SvEND(SV* sv)
Returns true if the SV has get magic or overloading. If either is true then the scalar is active data, and has the potential to return a new value every time it is accessed. Hence you must be careful to only read it once per user logical operation and work with that returned value. If neither is true then the scalar's value cannot change unless written to. 

        U32     SvGAMAGIC(SV* sv)
Expands the character buffer in the SV so that it has room for the indicated number of bytes (remember to reserve space for an extra trailing NUL character). Calls "sv_grow" to perform the expansion if necessary. Returns a pointer to the character buffer. 

        char *  SvGROW(SV* sv, STRLEN len)
Returns a U32 value indicating whether the SV contains an integer. 

        U32     SvIOK(SV* sv)
Returns a U32 value indicating whether the SV contains an integer. Checks the private setting. Use "SvIOK" instead. 

        U32     SvIOKp(SV* sv)
Returns a boolean indicating whether the SV contains a signed integer. 

        bool    SvIOK_notUV(SV* sv)
Unsets the IV status of an SV. 

        void    SvIOK_off(SV* sv)
Tells an SV that it is an integer. 

        void    SvIOK_on(SV* sv)
Tells an SV that it is an integer and disables all other OK bits. 

        void    SvIOK_only(SV* sv)
Tells and SV that it is an unsigned integer and disables all other OK bits. 

        void    SvIOK_only_UV(SV* sv)
Returns a boolean indicating whether the SV contains an unsigned integer. 

        bool    SvIOK_UV(SV* sv)
Returns a boolean indicating whether the SV is Copy-On-Write. (either shared hash key scalars, or full Copy On Write scalars if 5.9.0 is configured for COW) 

        bool    SvIsCOW(SV* sv)
Returns a boolean indicating whether the SV is Copy-On-Write shared hash key scalar. 

        bool    SvIsCOW_shared_hash(SV* sv)
Coerces the given SV to an integer and returns it. See "SvIVx" for a version which guarantees to evaluate sv only once. 

        IV      SvIV(SV* sv)
Returns the raw value in the SV's IV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvIV()". 

        IV      SvIVX(SV* sv)
Coerces the given SV to an integer and returns it. Guarantees to evaluate "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvIV". 

        IV      SvIVx(SV* sv)
Like "SvIV" but doesn't process magic. 

        IV      SvIV_nomg(SV* sv)
Set the value of the IV pointer in sv to val. It is possible to perform the same function of this macro with an lvalue assignment to "SvIVX". With future Perls, however, it will be more efficient to use "SvIV_set" instead of the lvalue assignment to "SvIVX". 

        void    SvIV_set(SV* sv, IV val)
Returns the size of the string buffer in the SV, not including any part attributable to "SvOOK". See "SvCUR". 

        STRLEN  SvLEN(SV* sv)
Set the actual length of the string which is in the SV. See "SvIV_set". 

        void    SvLEN_set(SV* sv, STRLEN len)
Set the value of the MAGIC pointer in sv to val. See "SvIV_set". 

        void    SvMAGIC_set(SV* sv, MAGIC* val)
Returns a U32 value indicating whether the SV contains a number, integer or double. 

        U32     SvNIOK(SV* sv)
Returns a U32 value indicating whether the SV contains a number, integer or double. Checks the private setting. Use "SvNIOK" instead. 

        U32     SvNIOKp(SV* sv)
Unsets the NV/IV status of an SV. 

        void    SvNIOK_off(SV* sv)
Returns a U32 value indicating whether the SV contains a double. 

        U32     SvNOK(SV* sv)
Returns a U32 value indicating whether the SV contains a double. Checks the private setting. Use "SvNOK" instead. 

        U32     SvNOKp(SV* sv)
Unsets the NV status of an SV. 

        void    SvNOK_off(SV* sv)
Tells an SV that it is a double. 

        void    SvNOK_on(SV* sv)
Tells an SV that it is a double and disables all other OK bits. 

        void    SvNOK_only(SV* sv)
Coerce the given SV to a double and return it. See "SvNVx" for a version which guarantees to evaluate sv only once. 

        NV      SvNV(SV* sv)
Returns the raw value in the SV's NV slot, without checks or conversions. Only use when you are sure SvNOK is true. See also "SvNV()". 

        NV      SvNVX(SV* sv)
Coerces the given SV to a double and returns it. Guarantees to evaluate "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvNV". 

        NV      SvNVx(SV* sv)
Set the value of the NV pointer in sv to val. See "SvIV_set". 

        void    SvNV_set(SV* sv, NV val)
Returns a U32 value indicating whether the value is defined. This is only meaningful for scalars. 

        U32     SvOK(SV* sv)
Returns a U32 indicating whether the SvIVX is a valid offset value for the SvPVX. This hack is used internally to speed up removal of characters from the beginning of a SvPV. When SvOOK is true, then the start of the allocated string buffer is really (SvPVX - SvIVX). 

        U32     SvOOK(SV* sv)
Returns a U32 value indicating whether the SV contains a character string. 

        U32     SvPOK(SV* sv)
Returns a U32 value indicating whether the SV contains a character string. Checks the private setting. Use "SvPOK" instead. 

        U32     SvPOKp(SV* sv)
Unsets the PV status of an SV. 

        void    SvPOK_off(SV* sv)
Tells an SV that it is a string. 

        void    SvPOK_on(SV* sv)
Tells an SV that it is a string and disables all other OK bits. Will also turn off the UTF-8 status. 

        void    SvPOK_only(SV* sv)
Tells an SV that it is a string and disables all other OK bits, and leaves the UTF-8 status as it was. 

        void    SvPOK_only_UTF8(SV* sv)
Returns a pointer to the string in the SV, or a stringified form of the SV if the SV does not contain a string. The SV may cache the stringified version becoming "SvPOK". Handles 'get' magic. See also "SvPVx" for a version which guarantees to evaluate sv only once. 

        char*   SvPV(SV* sv, STRLEN len)
Like "SvPV", but converts sv to byte representation first if necessary. 

        char*   SvPVbyte(SV* sv, STRLEN len)
Like "SvPV", but converts sv to byte representation first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVbyte" otherwise. 

        char*   SvPVbytex(SV* sv, STRLEN len)
Like "SvPV_force", but converts sv to byte representation first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVbyte_force" otherwise. 

        char*   SvPVbytex_force(SV* sv, STRLEN len)
Like "SvPV_force", but converts sv to byte representation first if necessary. 

        char*   SvPVbyte_force(SV* sv, STRLEN len)
Like "SvPV_nolen", but converts sv to byte representation first if necessary. 

        char*   SvPVbyte_nolen(SV* sv)
Like "SvPV", but converts sv to utf8 first if necessary. 

        char*   SvPVutf8(SV* sv, STRLEN len)
Like "SvPV", but converts sv to utf8 first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVutf8" otherwise. 

        char*   SvPVutf8x(SV* sv, STRLEN len)
Like "SvPV_force", but converts sv to utf8 first if necessary. Guarantees to evaluate sv only once; use the more efficient "SvPVutf8_force" otherwise. 

        char*   SvPVutf8x_force(SV* sv, STRLEN len)
Like "SvPV_force", but converts sv to utf8 first if necessary. 

        char*   SvPVutf8_force(SV* sv, STRLEN len)
Like "SvPV_nolen", but converts sv to utf8 first if necessary. 

        char*   SvPVutf8_nolen(SV* sv)
Returns a pointer to the physical string in the SV. The SV must contain a string. 

        char*   SvPVX(SV* sv)
A version of "SvPV" which guarantees to evaluate "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvPVX". 

        char*   SvPVx(SV* sv, STRLEN len)
Like "SvPV" but will force the SV into containing just a string ("SvPOK_only"). You want force if you are going to update the "SvPVX" directly. 

        char*   SvPV_force(SV* sv, STRLEN len)
Like "SvPV" but will force the SV into containing just a string ("SvPOK_only"). You want force if you are going to update the "SvPVX" directly. Doesn't process magic. 

        char*   SvPV_force_nomg(SV* sv, STRLEN len)
Returns a pointer to the string in the SV, or a stringified form of the SV if the SV does not contain a string. The SV may cache the stringified form becoming "SvPOK". Handles 'get' magic. 

        char*   SvPV_nolen(SV* sv)
Like "SvPV" but doesn't process magic. 

        char*   SvPV_nomg(SV* sv, STRLEN len)
Set the value of the PV pointer in sv to val. See "SvIV_set". 

        void    SvPV_set(SV* sv, char* val)
Returns the value of the object's reference count. 

        U32     SvREFCNT(SV* sv)
Decrements the reference count of the given SV. 

        void    SvREFCNT_dec(SV* sv)
Increments the reference count of the given SV.

All of the following SvREFCNT_inc* macros are optimized versions of SvREFCNT_inc, and can be replaced with SvREFCNT_inc.

        SV*     SvREFCNT_inc(SV* sv)
Same as SvREFCNT_inc, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller. 

        SV*     SvREFCNT_inc_NN(SV* sv)
Same as SvREFCNT_inc, but can only be used with expressions without side effects. Since we don't have to store a temporary value, it's faster. 

        SV*     SvREFCNT_inc_simple(SV* sv)
Same as SvREFCNT_inc_simple, but can only be used if you know sv is not NULL. Since we don't have to check the NULLness, it's faster and smaller. 

        SV*     SvREFCNT_inc_simple_NN(SV* sv)
Same as SvREFCNT_inc_simple, but can only be used if you don't need the return value. The macro doesn't need to return a meaningful value. 

        void    SvREFCNT_inc_simple_void(SV* sv)
Same as SvREFCNT_inc, but can only be used if you don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster. 

        void    SvREFCNT_inc_simple_void_NN(SV* sv)
Same as SvREFCNT_inc, but can only be used if you don't need the return value. The macro doesn't need to return a meaningful value. 

        void    SvREFCNT_inc_void(SV* sv)
Same as SvREFCNT_inc, but can only be used if you don't need the return value, and you know that sv is not NULL. The macro doesn't need to return a meaningful value, or check for NULLness, so it's smaller and faster. 

        void    SvREFCNT_inc_void_NN(SV* sv)
Tests if the SV is an RV. 

        U32     SvROK(SV* sv)
Unsets the RV status of an SV. 

        void    SvROK_off(SV* sv)
Tells an SV that it is an RV. 

        void    SvROK_on(SV* sv)
Dereferences an RV to return the SV. 

        SV*     SvRV(SV* sv)
Set the value of the RV pointer in sv to val. See "SvIV_set". 

        void    SvRV_set(SV* sv, SV* val)
Returns the stash of the SV. 

        HV*     SvSTASH(SV* sv)
Set the value of the STASH pointer in sv to val. See "SvIV_set". 

        void    SvSTASH_set(SV* sv, HV* val)
Taints an SV if tainting is enabled. 

        void    SvTAINT(SV* sv)
Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not. 

        bool    SvTAINTED(SV* sv)
Untaints an SV. Be very careful with this routine, as it short-circuits some of Perl's fundamental security features. XS module authors should not use this function unless they fully understand all the implications of unconditionally untainting the value. Untainting should be done in the standard perl fashion, via a carefully crafted regexp, rather than directly untainting variables. 

        void    SvTAINTED_off(SV* sv)
Marks an SV as tainted if tainting is enabled. 

        void    SvTAINTED_on(SV* sv)
Returns a boolean indicating whether Perl would evaluate the SV as true or false. See SvOK() for a defined/undefined test. Does not handle 'get' magic. 

        bool    SvTRUE(SV* sv)
Returns the type of the SV. See "svtype". 

        svtype  SvTYPE(SV* sv)
Returns a boolean indicating whether the SV contains an unsigned integer. 

        bool    SvUOK(SV* sv)
Used to upgrade an SV to a more complex form. Uses "sv_upgrade" to perform the upgrade if necessary. See "svtype". 

        void    SvUPGRADE(SV* sv, svtype type)
Returns a U32 value indicating whether the SV contains UTF-8 encoded data. Call this after SvPV() in case any call to string overloading updates the internal flag. 

        U32     SvUTF8(SV* sv)
Unsets the UTF-8 status of an SV. 

        void    SvUTF8_off(SV *sv)
Turn on the UTF-8 status of an SV (the data is not changed, just the flag). Do not use frivolously. 

        void    SvUTF8_on(SV *sv)
Coerces the given SV to an unsigned integer and returns it. See "SvUVx" for a version which guarantees to evaluate sv only once. 

        UV      SvUV(SV* sv)
Returns the raw value in the SV's UV slot, without checks or conversions. Only use when you are sure SvIOK is true. See also "SvUV()". 

        UV      SvUVX(SV* sv)
Coerces the given SV to an unsigned integer and returns it. Guarantees to "sv" only once. Only use this if "sv" is an expression with side effects, otherwise use the more efficient "SvUV". 

        UV      SvUVx(SV* sv)
Like "SvUV" but doesn't process magic. 

        UV      SvUV_nomg(SV* sv)
Set the value of the UV pointer in sv to val. See "SvIV_set". 

        void    SvUV_set(SV* sv, UV val)
Returns a boolean indicating whether the SV contains a v-string. 

        bool    SvVOK(SV* sv)
Like "sv_catpvn" but doesn't process magic. 

        void    sv_catpvn_nomg(SV* sv, const char* ptr, STRLEN len)
Like "sv_catsv" but doesn't process magic. 

        void    sv_catsv_nomg(SV* dsv, SV* ssv)
Returns a boolean indicating whether the SV is derived from the specified class at the C level. To check derivation at the Perl level, call "isa()" as a normal Perl method. 

        bool    sv_derived_from(SV* sv, const char* name)
Returns a boolean indicating whether the SV performs a specific, named role. The SV can be a Perl object or the name of a Perl class. 

        bool    sv_does(SV* sv, const char* name)
Dump the contents of all SVs not yet freed. (Debugging aid). 

        void    sv_report_used()
Like "sv_setsv" but doesn't process magic. 

        void    sv_setsv_nomg(SV* dsv, SV* ssv)
Like sv_utf8_upgrade, but doesn't do magic on "sv" 

        STRLEN  sv_utf8_upgrade_nomg(NN SV *sv)

SV-Body Allocation

Test if the content of an SV looks like a number (or is a number). "Inf" and "Infinity" are treated as numbers (so will not issue a non-numeric warning), even if your atof() doesn't grok them. 

        I32     looks_like_number(SV* sv)
Creates an RV wrapper for an SV. The reference count for the original SV is not incremented. 

        SV*     newRV_noinc(SV* sv)
Creates a new SV. A non-zero "len" parameter indicates the number of bytes of preallocated string space the SV should have. An extra byte for a trailing NUL is also reserved. (SvPOK is not set for the SV even if string space is allocated.) The reference count for the new SV is set to 1.

In 5.9.3, newSV() replaces the older NEWSV() API, and drops the first parameter, x, a debug aid which allowed callers to identify themselves. This aid has been superseded by a new build option, PERL_MEM_LOG (see "PERL_MEM_LOG" in perlhack). The older API is still there for use in XS modules supporting older perls.

        SV*     newSV(STRLEN len)
Creates a new SV from the hash key structure. It will generate scalars that point to the shared string table where possible. Returns a new (undefined) SV if the hek is NULL. 

        SV*     newSVhek(const HEK *hek)
Creates a new SV and copies an integer into it. The reference count for the SV is set to 1. 

        SV*     newSViv(IV i)
Creates a new SV and copies a floating point value into it. The reference count for the SV is set to 1. 

        SV*     newSVnv(NV n)
Creates a new SV and copies a string into it. The reference count for the SV is set to 1. If "len" is zero, Perl will compute the length using strlen(). For efficiency, consider using "newSVpvn" instead. 

        SV*     newSVpv(const char* s, STRLEN len)
Creates a new SV and initializes it with the string formatted like "sprintf". 

        SV*     newSVpvf(const char* pat, ...)
Creates a new SV and copies a string into it. The reference count for the SV is set to 1. Note that if "len" is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least "len" bytes long. If the "s" argument is NULL the new SV will be undefined. 

        SV*     newSVpvn(const char* s, STRLEN len)
Creates a new SV and copies a string into it. The reference count for the SV is set to 1. Note that if "len" is zero, Perl will create a zero length string. You are responsible for ensuring that the source string is at least "len" bytes long. If the "s" argument is NULL the new SV will be undefined. Currently the only flag bits accepted are "SVf_UTF8" and "SVs_TEMP". If "SVs_TEMP" is set, then "sv2mortal()" is called on the result before returning. If "SVf_UTF8" is set, then it will be set on the new SV. "newSVpvn_utf8()" is a convenience wrapper for this function, defined as 

    #define newSVpvn_utf8(s, len, u)                    \
        newSVpvn_flags((s), (len), (u) ? SVf_UTF8 : 0)
        SV*     newSVpvn_flags(const char* s, STRLEN len, U32 flags)
Creates a new SV with its SvPVX_const pointing to a shared string in the string table. If the string does not already exist in the table, it is created first. Turns on READONLY and FAKE. If the "hash" parameter is non-zero, that value is used; otherwise the hash is computed. The string's hash can be later be retrieved from the SV with the "SvSHARED_HASH()" macro. The idea here is that as the string table is used for shared hash keys these strings will have SvPVX_const == HeKEY and hash lookup will avoid string compare. 

        SV*     newSVpvn_share(const char* s, I32 len, U32 hash)
Like "newSVpvn", but takes a literal string instead of a string/length pair. 

        SV*     newSVpvs(const char* s)
Like "newSVpvn_flags", but takes a literal string instead of a string/length pair. 

        SV*     newSVpvs_flags(const char* s, U32 flags)
Like "newSVpvn_share", but takes a literal string instead of a string/length pair and omits the hash parameter. 

        SV*     newSVpvs_share(const char* s)
Creates a new SV for the RV, "rv", to point to. If "rv" is not an RV then it will be upgraded to one. If "classname" is non-null then the new SV will be blessed in the specified package. The new SV is returned and its reference count is 1. 

        SV*     newSVrv(SV* rv, const char* classname)
Creates a new SV which is an exact duplicate of the original SV. (Uses "sv_setsv"). 

        SV*     newSVsv(SV* old)
Creates a new SV and copies an unsigned integer into it. The reference count for the SV is set to 1. 

        SV*     newSVuv(UV u)
Creates a new SV, of the type specified. The reference count for the new SV is set to 1. 

        SV*     newSV_type(svtype type)
This function is only called on magical items, and is only used by sv_true() or its macro equivalent. 

        bool    sv_2bool(SV* sv)
Using various gambits, try to get a CV from an SV; in addition, try if possible to set *st and *gvp to the stash and GV associated with it. The flags in "lref" are passed to sv_fetchsv. 

        CV*     sv_2cv(SV* sv, HV** st, GV** gvp, I32 lref)
Using various gambits, try to get an IO from an SV: the IO slot if its a GV; or the recursive result if we're an RV; or the IO slot of the symbol named after the PV if we're a string. 

        IO*     sv_2io(SV* sv)
Return the integer value of an SV, doing any necessary string conversion. If flags includes SV_GMAGIC, does an mg_get() first. Normally used via the "SvIV(sv)" and "SvIVx(sv)" macros. 

        IV      sv_2iv_flags(SV* sv, I32 flags)
Marks an existing SV as mortal. The SV will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. SvTEMP() is turned on which means that the SV's string buffer can be "stolen" if this SV is copied. See also "sv_newmortal" and "sv_mortalcopy". 

        SV*     sv_2mortal(SV* sv)
Return the num value of an SV, doing any necessary string or integer conversion, magic etc. Normally used via the "SvNV(sv)" and "SvNVx(sv)" macros. 

        NV      sv_2nv(SV* sv)
Return a pointer to the byte-encoded representation of the SV, and set *lp to its length. May cause the SV to be downgraded from UTF-8 as a side-effect.

Usually accessed via the "SvPVbyte" macro.

        char*   sv_2pvbyte(SV* sv, STRLEN* lp)
Return a pointer to the UTF-8-encoded representation of the SV, and set *lp to its length. May cause the SV to be upgraded to UTF-8 as a side-effect.

Usually accessed via the "SvPVutf8" macro.

        char*   sv_2pvutf8(SV* sv, STRLEN* lp)
Returns a pointer to the string value of an SV, and sets *lp to its length. If flags includes SV_GMAGIC, does an mg_get() first. Coerces sv to a string if necessary. Normally invoked via the "SvPV_flags" macro. "sv_2pv()" and "sv_2pv_nomg" usually end up here too. 

        char*   sv_2pv_flags(SV* sv, STRLEN* lp, I32 flags)
Return the unsigned integer value of an SV, doing any necessary string conversion. If flags includes SV_GMAGIC, does an mg_get() first. Normally used via the "SvUV(sv)" and "SvUVx(sv)" macros. 

        UV      sv_2uv_flags(SV* sv, I32 flags)
Remove any string offset. You should normally use the "SvOOK_off" macro wrapper instead. 

        int     sv_backoff(SV* sv)
Blesses an SV into a specified package. The SV must be an RV. The package must be designated by its stash (see "gv_stashpv()"). The reference count of the SV is unaffected. 

        SV*     sv_bless(SV* sv, HV* stash)
Concatenates the string onto the end of the string which is in the SV. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpv_mg". 

        void    sv_catpv(SV* sv, const char* ptr)
Processes its arguments like "sprintf" and appends the formatted output to an SV. If the appended data contains "wide" characters (including, but not limited to, SVs with a UTF-8 PV formatted with %s, and characters >255 formatted with %c), the original SV might get upgraded to UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpvf_mg". If the original SV was UTF-8, the pattern should be valid UTF-8; if the original SV was bytes, the pattern should be too. 

        void    sv_catpvf(SV* sv, const char* pat, ...)
Like "sv_catpvf", but also handles 'set' magic. 

        void    sv_catpvf_mg(SV *sv, const char* pat, ...)
Concatenates the string onto the end of the string which is in the SV. The "len" indicates number of bytes to copy. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. Handles 'get' magic, but not 'set' magic. See "sv_catpvn_mg". 

        void    sv_catpvn(SV *dsv, const char *sstr, STRLEN len)
Concatenates the string onto the end of the string which is in the SV. The "len" indicates number of bytes to copy. If the SV has the UTF-8 status set, then the bytes appended should be valid UTF-8. If "flags" has "SV_GMAGIC" bit set, will "mg_get" on "dsv" if appropriate, else not. "sv_catpvn" and "sv_catpvn_nomg" are implemented in terms of this function. 

        void    sv_catpvn_flags(SV *dstr, const char *sstr, STRLEN len, I32 flags)
Like "sv_catpvn", but takes a literal string instead of a string/length pair. 

        void    sv_catpvs(SV* sv, const char* s)
Like "sv_catpv", but also handles 'set' magic. 

        void    sv_catpv_mg(SV *sv, const char *ptr)
Concatenates the string from SV "ssv" onto the end of the string in SV "dsv". Modifies "dsv" but not "ssv". Handles 'get' magic, but not 'set' magic. See "sv_catsv_mg". 

        void    sv_catsv(SV *dstr, SV *sstr)
Concatenates the string from SV "ssv" onto the end of the string in SV "dsv". Modifies "dsv" but not "ssv". If "flags" has "SV_GMAGIC" bit set, will "mg_get" on the SVs if appropriate, else not. "sv_catsv" and "sv_catsv_nomg" are implemented in terms of this function. 

        void    sv_catsv_flags(SV* dsv, SV* ssv, I32 flags)
Efficient removal of characters from the beginning of the string buffer. SvPOK(sv) must be true and the "ptr" must be a pointer to somewhere inside the string buffer. The "ptr" becomes the first character of the adjusted string. Uses the "OOK hack". Beware: after this function returns, "ptr" and SvPVX_const(sv) may no longer refer to the same chunk of data. 

        void    sv_chop(SV* sv, const char* ptr)
Clear an SV: call any destructors, free up any memory used by the body, and free the body itself. The SV's head is not freed, although its type is set to all 1's so that it won't inadvertently be assumed to be live during global destruction etc. This function should only be called when REFCNT is zero. Most of the time you'll want to call "sv_free()" (or its macro wrapper "SvREFCNT_dec") instead. 

        void    sv_clear(SV* sv)
Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the string in "sv1" is less than, equal to, or greater than the string in "sv2". Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp_locale". 

        I32     sv_cmp(SV* sv1, SV* sv2)
Compares the strings in two SVs in a locale-aware manner. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. See also "sv_cmp". 

        I32     sv_cmp_locale(SV* sv1, SV* sv2)
Add Collate Transform magic to an SV if it doesn't already have it.

Any scalar variable may carry PERL_MAGIC_collxfrm magic that contains the scalar data of the variable, but transformed to such a format that a normal memory comparison can be used to compare the data according to the locale settings.

        char*   sv_collxfrm(SV* sv, STRLEN* nxp)
Copies a stringified representation of the source SV into the destination SV. Automatically performs any necessary mg_get and coercion of numeric values into strings. Guaranteed to preserve UTF8 flag even from overloaded objects. Similar in nature to sv_2pv[_flags] but operates directly on an SV instead of just the string. Mostly uses sv_2pv_flags to do its work, except when that would lose the UTF-8'ness of the PV. 

        void    sv_copypv(SV* dsv, SV* ssv)
Auto-decrement of the value in the SV, doing string to numeric conversion if necessary. Handles 'get' magic. 

        void    sv_dec(SV* sv)
Returns a boolean indicating whether the strings in the two SVs are identical. Is UTF-8 and 'use bytes' aware, handles get magic, and will coerce its args to strings if necessary. 

        I32     sv_eq(SV* sv1, SV* sv2)
Undo various types of fakery on an SV: if the PV is a shared string, make a private copy; if we're a ref, stop refing; if we're a glob, downgrade to an xpvmg; if we're a copy-on-write scalar, this is the on-write time when we do the copy, and is also used locally. If "SV_COW_DROP_PV" is set then a copy-on-write scalar drops its PV buffer (if any) and becomes SvPOK_off rather than making a copy. (Used where this scalar is about to be set to some other value.) In addition, the "flags" parameter gets passed to "sv_unref_flags()" when unrefing. "sv_force_normal" calls this function with flags set to 0. 

        void    sv_force_normal_flags(SV *sv, U32 flags)
Decrement an SV's reference count, and if it drops to zero, call "sv_clear" to invoke destructors and free up any memory used by the body; finally, deallocate the SV's head itself. Normally called via a wrapper macro "SvREFCNT_dec". 

        void    sv_free(SV* sv)
Get a line from the filehandle and store it into the SV, optionally appending to the currently-stored string. 

        char*   sv_gets(SV* sv, PerlIO* fp, I32 append)
Expands the character buffer in the SV. If necessary, uses "sv_unref" and upgrades the SV to "SVt_PV". Returns a pointer to the character buffer. Use the "SvGROW" wrapper instead. 

        char*   sv_grow(SV* sv, STRLEN newlen)
Auto-increment of the value in the SV, doing string to numeric conversion if necessary. Handles 'get' magic. 

        void    sv_inc(SV* sv)
Inserts a string at the specified offset/length within the SV. Similar to the Perl substr() function. Handles get magic. 

        void    sv_insert(SV *bigstr, STRLEN offset, STRLEN len, const char *little, STRLEN littlelen)
Same as "sv_insert", but the extra "flags" are passed the "SvPV_force_flags" that applies to "bigstr". 

        void    sv_insert_flags(SV *const bigstr, const STRLEN offset, const STRLEN len, const char *const little, const STRLEN littlelen, const U32 flags)
Returns a boolean indicating whether the SV is blessed into the specified class. This does not check for subtypes; use "sv_derived_from" to verify an inheritance relationship. 

        int     sv_isa(SV* sv, const char* name)
Returns a boolean indicating whether the SV is an RV pointing to a blessed object. If the SV is not an RV, or if the object is not blessed, then this will return false. 

        int     sv_isobject(SV* sv)
Returns the length of the string in the SV. Handles magic and type coercion. See also "SvCUR", which gives raw access to the xpv_cur slot. 

        STRLEN  sv_len(SV* sv)
Returns the number of characters in the string in an SV, counting wide UTF-8 bytes as a single character. Handles magic and type coercion. 

        STRLEN  sv_len_utf8(SV* sv)
Adds magic to an SV. First upgrades "sv" to type "SVt_PVMG" if necessary, then adds a new magic item of type "how" to the head of the magic list.

See "sv_magicext" (which "sv_magic" now calls) for a description of the handling of the "name" and "namlen" arguments.

You need to use "sv_magicext" to add magic to SvREADONLY SVs and also to add more than one instance of the same 'how'.

        void    sv_magic(SV* sv, SV* obj, int how, const char* name, I32 namlen)
Adds magic to an SV, upgrading it if necessary. Applies the supplied vtable and returns a pointer to the magic added.

Note that "sv_magicext" will allow things that "sv_magic" will not. In particular, you can add magic to SvREADONLY SVs, and add more than one instance of the same 'how'.

If "namlen" is greater than zero then a "savepvn" copy of "name" is stored, if "namlen" is zero then "name" is stored as-is and - as another special case - if "(name && namlen == HEf_SVKEY)" then "name" is assumed to contain an "SV*" and is stored as-is with its REFCNT incremented.

(This is now used as a subroutine by "sv_magic".)

        MAGIC * sv_magicext(SV* sv, SV* obj, int how, const MGVTBL *vtbl, const char* name, I32 namlen)
Creates a new SV which is a copy of the original SV (using "sv_setsv"). The new SV is marked as mortal. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_newmortal" and "sv_2mortal". 

        SV*     sv_mortalcopy(SV* oldsv)
Creates a new null SV which is mortal. The reference count of the SV is set to 1. It will be destroyed "soon", either by an explicit call to FREETMPS, or by an implicit call at places such as statement boundaries. See also "sv_mortalcopy" and "sv_2mortal". 

        SV*     sv_newmortal()
Increment an SV's reference count. Use the "SvREFCNT_inc()" wrapper instead. 

        SV*     sv_newref(SV* sv)
Converts the value pointed to by offsetp from a count of bytes from the start of the string, to a count of the equivalent number of UTF-8 chars. Handles magic and type coercion. 

        void    sv_pos_b2u(SV* sv, I32* offsetp)
Converts the value pointed to by offsetp from a count of UTF-8 chars from the start of the string, to a count of the equivalent number of bytes; if lenp is non-zero, it does the same to lenp, but this time starting from the offset, rather than from the start of the string. Handles magic and type coercion. 

        void    sv_pos_u2b(SV* sv, I32* offsetp, I32* lenp)
The backend for the "SvPVbytex_force" macro. Always use the macro instead. 

        char*   sv_pvbyten_force(SV* sv, STRLEN* lp)
Get a sensible string out of the SV somehow. A private implementation of the "SvPV_force" macro for compilers which can't cope with complex macro expressions. Always use the macro instead. 

        char*   sv_pvn_force(SV* sv, STRLEN* lp)
Get a sensible string out of the SV somehow. If "flags" has "SV_GMAGIC" bit set, will "mg_get" on "sv" if appropriate, else not. "sv_pvn_force" and "sv_pvn_force_nomg" are implemented in terms of this function. You normally want to use the various wrapper macros instead: see "SvPV_force" and "SvPV_force_nomg" 

        char*   sv_pvn_force_flags(SV* sv, STRLEN* lp, I32 flags)
The backend for the "SvPVutf8x_force" macro. Always use the macro instead. 

        char*   sv_pvutf8n_force(SV* sv, STRLEN* lp)
Returns a string describing what the SV is a reference to. 

        const char*     sv_reftype(const SV* sv, int ob)
Make the first argument a copy of the second, then delete the original. The target SV physically takes over ownership of the body of the source SV and inherits its flags; however, the target keeps any magic it owns, and any magic in the source is discarded. Note that this is a rather specialist SV copying operation; most of the time you'll want to use "sv_setsv" or one of its many macro front-ends. 

        void    sv_replace(SV* sv, SV* nsv)
Underlying implementation for the "reset" Perl function. Note that the perl-level function is vaguely deprecated. 

        void    sv_reset(const char* s, HV* stash)
Weaken a reference: set the "SvWEAKREF" flag on this RV; give the referred-to SV "PERL_MAGIC_backref" magic if it hasn't already; and push a back-reference to this RV onto the array of backreferences associated with that magic. If the RV is magical, set magic will be called after the RV is cleared. 

        SV*     sv_rvweaken(SV *sv)
Copies an integer into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setiv_mg". 

        void    sv_setiv(SV* sv, IV num)
Like "sv_setiv", but also handles 'set' magic. 

        void    sv_setiv_mg(SV *sv, IV i)
Copies a double into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setnv_mg". 

        void    sv_setnv(SV* sv, NV num)
Like "sv_setnv", but also handles 'set' magic. 

        void    sv_setnv_mg(SV *sv, NV num)
Copies a string into an SV. The string must be null-terminated. Does not handle 'set' magic. See "sv_setpv_mg". 

        void    sv_setpv(SV* sv, const char* ptr)
Works like "sv_catpvf" but copies the text into the SV instead of appending it. Does not handle 'set' magic. See "sv_setpvf_mg". 

        void    sv_setpvf(SV* sv, const char* pat, ...)
Like "sv_setpvf", but also handles 'set' magic. 

        void    sv_setpvf_mg(SV *sv, const char* pat, ...)
Copies an integer into the given SV, also updating its string value. Does not handle 'set' magic. See "sv_setpviv_mg". 

        void    sv_setpviv(SV* sv, IV num)
Like "sv_setpviv", but also handles 'set' magic. 

        void    sv_setpviv_mg(SV *sv, IV iv)
Copies a string into an SV. The "len" parameter indicates the number of bytes to be copied. If the "ptr" argument is NULL the SV will become undefined. Does not handle 'set' magic. See "sv_setpvn_mg". 

        void    sv_setpvn(SV* sv, const char* ptr, STRLEN len)
Like "sv_setpvn", but also handles 'set' magic. 

        void    sv_setpvn_mg(SV *sv, const char *ptr, STRLEN len)
Like "sv_setpvn", but takes a literal string instead of a string/length pair. 

        void    sv_setpvs(SV* sv, const char* s)
Like "sv_setpv", but also handles 'set' magic. 

        void    sv_setpv_mg(SV *sv, const char *ptr)
Copies an integer into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned. 

        SV*     sv_setref_iv(SV* rv, const char* classname, IV iv)
Copies a double into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned. 

        SV*     sv_setref_nv(SV* rv, const char* classname, NV nv)
Copies a pointer into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. If the "pv" argument is NULL then "PL_sv_undef" will be placed into the SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

Do not use with other Perl types such as HV, AV, SV, CV, because those objects will become corrupted by the pointer copy process.

Note that "sv_setref_pvn" copies the string while this copies the pointer.

        SV*     sv_setref_pv(SV* rv, const char* classname, void* pv)
Copies a string into a new SV, optionally blessing the SV. The length of the string must be specified with "n". The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned.

Note that "sv_setref_pv" copies the pointer while this copies the string.

        SV*     sv_setref_pvn(SV* rv, const char* classname, const char* pv, STRLEN n)
Copies an unsigned integer into a new SV, optionally blessing the SV. The "rv" argument will be upgraded to an RV. That RV will be modified to point to the new SV. The "classname" argument indicates the package for the blessing. Set "classname" to "NULL" to avoid the blessing. The new SV will have a reference count of 1, and the RV will be returned. 

        SV*     sv_setref_uv(SV* rv, const char* classname, UV uv)
Copies the contents of the source SV "ssv" into the destination SV "dsv". The source SV may be destroyed if it is mortal, so don't use this function if the source SV needs to be reused. Does not handle 'set' magic. Loosely speaking, it performs a copy-by-value, obliterating any previous content of the destination.

You probably want to use one of the assortment of wrappers, such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and "SvSetMagicSV_nosteal".

        void    sv_setsv(SV *dstr, SV *sstr)
Copies the contents of the source SV "ssv" into the destination SV "dsv". The source SV may be destroyed if it is mortal, so don't use this function if the source SV needs to be reused. Does not handle 'set' magic. Loosely speaking, it performs a copy-by-value, obliterating any previous content of the destination. If the "flags" parameter has the "SV_GMAGIC" bit set, will "mg_get" on "ssv" if appropriate, else not. If the "flags" parameter has the "NOSTEAL" bit set then the buffers of temps will not be stolen. <sv_setsv> and "sv_setsv_nomg" are implemented in terms of this function.

You probably want to use one of the assortment of wrappers, such as "SvSetSV", "SvSetSV_nosteal", "SvSetMagicSV" and "SvSetMagicSV_nosteal".

This is the primary function for copying scalars, and most other copy-ish functions and macros use this underneath.

        void    sv_setsv_flags(SV *dstr, SV *sstr, I32 flags)
Like "sv_setsv", but also handles 'set' magic. 

        void    sv_setsv_mg(SV *dstr, SV *sstr)
Copies an unsigned integer into the given SV, upgrading first if necessary. Does not handle 'set' magic. See also "sv_setuv_mg". 

        void    sv_setuv(SV* sv, UV num)
Like "sv_setuv", but also handles 'set' magic. 

        void    sv_setuv_mg(SV *sv, UV u)
Test an SV for taintedness. Use "SvTAINTED" instead. bool sv_tainted(SV* sv)
Returns true if the SV has a true value by Perl's rules. Use the "SvTRUE" macro instead, which may call "sv_true()" or may instead use an in-line version. 

        I32     sv_true(SV *sv)
Removes all magic of type "type" from an SV. 

        int     sv_unmagic(SV* sv, int type)
Unsets the RV status of the SV, and decrements the reference count of whatever was being referenced by the RV. This can almost be thought of as a reversal of "newSVrv". The "cflags" argument can contain "SV_IMMEDIATE_UNREF" to force the reference count to be decremented (otherwise the decrementing is conditional on the reference count being different from one or the reference being a readonly SV). See "SvROK_off". 

        void    sv_unref_flags(SV *ref, U32 flags)
Untaint an SV. Use "SvTAINTED_off" instead. void sv_untaint(SV* sv)
Upgrade an SV to a more complex form. Generally adds a new body type to the SV, then copies across as much information as possible from the old body. You generally want to use the "SvUPGRADE" macro wrapper. See also "svtype". 

        void    sv_upgrade(SV* sv, svtype new_type)
Tells an SV to use "ptr" to find its string value. Normally the string is stored inside the SV but sv_usepvn allows the SV to use an outside string. The "ptr" should point to memory that was allocated by "malloc". The string length, "len", must be supplied. By default this function will realloc (i.e. move) the memory pointed to by "ptr", so that pointer should not be freed or used by the programmer after giving it to sv_usepvn, and neither should any pointers from "behind" that pointer (e.g. ptr + 1) be used.

If "flags" & SV_SMAGIC is true, will call SvSETMAGIC. If "flags" & SV_HAS_TRAILING_NUL is true, then "ptr[len]" must be NUL, and the realloc will be skipped. (i.e. the buffer is actually at least 1 byte longer than "len", and already meets the requirements for storing in "SvPVX")

        void    sv_usepvn_flags(SV* sv, char* ptr, STRLEN len, U32 flags)
If the PV of the SV is an octet sequence in UTF-8 and contains a multiple-byte character, the "SvUTF8" flag is turned on so that it looks like a character. If the PV contains only single-byte characters, the "SvUTF8" flag stays being off. Scans PV for validity and returns false if the PV is invalid UTF-8.

NOTE: this function is experimental and may change or be removed without notice.

        bool    sv_utf8_decode(SV *sv)
Attempts to convert the PV of an SV from characters to bytes. If the PV contains a character that cannot fit in a byte, this conversion will fail; in this case, either returns false or, if "fail_ok" is not true, croaks.

This is not as a general purpose Unicode to byte encoding interface: use the Encode extension for that.

NOTE: this function is experimental and may change or be removed without notice.

        bool    sv_utf8_downgrade(SV *sv, bool fail_ok)
Converts the PV of an SV to UTF-8, but then turns the "SvUTF8" flag off so that it looks like octets again. 

        void    sv_utf8_encode(SV *sv)
Converts the PV of an SV to its UTF-8-encoded form. Forces the SV to string form if it is not already. Will "mg_get" on "sv" if appropriate. Always sets the SvUTF8 flag to avoid future validity checks even if the whole string is the same in UTF-8 as not. Returns the number of bytes in the converted string

This is not as a general purpose byte encoding to Unicode interface: use the Encode extension for that.

        STRLEN  sv_utf8_upgrade(SV *sv)
Converts the PV of an SV to its UTF-8-encoded form. Forces the SV to string form if it is not already. Always sets the SvUTF8 flag to avoid future validity checks even if all the bytes are invariant in UTF-8. If "flags" has "SV_GMAGIC" bit set, will "mg_get" on "sv" if appropriate, else not. Returns the number of bytes in the converted string "sv_utf8_upgrade" and "sv_utf8_upgrade_nomg" are implemented in terms of this function.

This is not as a general purpose byte encoding to Unicode interface: use the Encode extension for that.

        STRLEN  sv_utf8_upgrade_flags(SV *sv, I32 flags)
Like sv_utf8_upgrade, but doesn't do magic on "sv" 

        STRLEN  sv_utf8_upgrade_nomg(SV *sv)
Processes its arguments like "vsprintf" and appends the formatted output to an SV. Does not handle 'set' magic. See "sv_vcatpvf_mg".

Usually used via its frontend "sv_catpvf".

        void    sv_vcatpvf(SV* sv, const char* pat, va_list* args)
Processes its arguments like "vsprintf" and appends the formatted output to an SV. Uses an array of SVs if the C style variable argument list is missing (NULL). When running with taint checks enabled, indicates via "maybe_tainted" if results are untrustworthy (often due to the use of locales).

Usually used via one of its frontends "sv_vcatpvf" and "sv_vcatpvf_mg".

        void    sv_vcatpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)
Like "sv_vcatpvf", but also handles 'set' magic.

Usually used via its frontend "sv_catpvf_mg".

        void    sv_vcatpvf_mg(SV* sv, const char* pat, va_list* args)
Works like "sv_vcatpvf" but copies the text into the SV instead of appending it. Does not handle 'set' magic. See "sv_vsetpvf_mg".

Usually used via its frontend "sv_setpvf".

        void    sv_vsetpvf(SV* sv, const char* pat, va_list* args)
Works like "sv_vcatpvfn" but copies the text into the SV instead of appending it.

Usually used via one of its frontends "sv_vsetpvf" and "sv_vsetpvf_mg".

        void    sv_vsetpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)
Like "sv_vsetpvf", but also handles 'set' magic.

Usually used via its frontend "sv_setpvf_mg".

        void    sv_vsetpvf_mg(SV* sv, const char* pat, va_list* args)

Unicode Support

Converts a string "s" of length "len" from UTF-8 into native byte encoding. Unlike "utf8_to_bytes" but like "bytes_to_utf8", returns a pointer to the newly-created string, and updates "len" to contain the new length. Returns the original string if no conversion occurs, "len" is unchanged. Do nothing if "is_utf8" points to 0. Sets "is_utf8" to 0 if "s" is converted or consisted entirely of characters that are invariant in utf8 (i.e., US-ASCII on non-EBCDIC machines).

NOTE: this function is experimental and may change or be removed without notice.

        U8*     bytes_from_utf8(const U8 *s, STRLEN *len, bool *is_utf8)
Converts a string "s" of length "len" from the native encoding into UTF-8. Returns a pointer to the newly-created string, and sets "len" to reflect the new length.

A NUL character will be written after the end of the string.

If you want to convert to UTF-8 from encodings other than the native (Latin1 or EBCDIC), see sv_recode_to_utf8().

NOTE: this function is experimental and may change or be removed without notice.

        U8*     bytes_to_utf8(const U8 *s, STRLEN *len)
Return true if the strings s1 and s2 differ case-insensitively, false if not (if they are equal case-insensitively). If u1 is true, the string s1 is assumed to be in UTF-8-encoded Unicode. If u2 is true, the string s2 is assumed to be in UTF-8-encoded Unicode. If u1 or u2 are false, the respective string is assumed to be in native 8-bit encoding.

If the pe1 and pe2 are non-NULL, the scanning pointers will be copied in there (they will point at the beginning of the next character). If the pointers behind pe1 or pe2 are non-NULL, they are the end pointers beyond which scanning will not continue under any circumstances. If the byte lengths l1 and l2 are non-zero, s1+l1 and s2+l2 will be used as goal end pointers that will also stop the scan, and which qualify towards defining a successful match: all the scans that define an explicit length must reach their goal pointers for a match to succeed).

For case-insensitiveness, the "casefolding" of Unicode is used instead of upper/lowercasing both the characters, see http://www.unicode.org/unicode/reports/tr21/ (Case Mappings).

        I32     ibcmp_utf8(const char *s1, char **pe1, UV l1, bool u1, const char *s2, char **pe2, UV l2, bool u2)
Tests if some arbitrary number of bytes begins in a valid UTF-8 character. Note that an INVARIANT (i.e. ASCII on non-EBCDIC machines) character is a valid UTF-8 character. The actual number of bytes in the UTF-8 character will be returned if it is valid, otherwise 0. 

        STRLEN  is_utf8_char(const U8 *s)
Returns true if first "len" bytes of the given string form a valid UTF-8 string, false otherwise. Note that 'a valid UTF-8 string' does not mean 'a string that contains code points above 0x7F encoded in UTF-8' because a valid ASCII string is a valid UTF-8 string.

See also is_utf8_string_loclen() and is_utf8_string_loc().

        bool    is_utf8_string(const U8 *s, STRLEN len)
Like is_utf8_string() but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the "ep".

See also is_utf8_string_loclen() and is_utf8_string().

        bool    is_utf8_string_loc(const U8 *s, STRLEN len, const U8 **p)
Like is_utf8_string() but stores the location of the failure (in the case of "utf8ness failure") or the location s+len (in the case of "utf8ness success") in the "ep", and the number of UTF-8 encoded characters in the "el".

See also is_utf8_string_loc() and is_utf8_string().

        bool    is_utf8_string_loclen(const U8 *s, STRLEN len, const U8 **ep, STRLEN *el)
Build to the scalar dsv a displayable version of the string spv, length len, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

The flags argument can have UNI_DISPLAY_ISPRINT set to display isPRINT()able characters as themselves, UNI_DISPLAY_BACKSLASH to display the \\[nrfta\\] as the backslashed versions (like '\n') (UNI_DISPLAY_BACKSLASH is preferred over UNI_DISPLAY_ISPRINT for \\). UNI_DISPLAY_QQ (and its alias UNI_DISPLAY_REGEX) have both UNI_DISPLAY_BACKSLASH and UNI_DISPLAY_ISPRINT turned on.

The pointer to the PV of the dsv is returned.

        char*   pv_uni_display(SV *dsv, const U8 *spv, STRLEN len, STRLEN pvlim, UV flags)
The encoding is assumed to be an Encode object, the PV of the ssv is assumed to be octets in that encoding and decoding the input starts from the position which (PV + *offset) pointed to. The dsv will be concatenated the decoded UTF-8 string from ssv. Decoding will terminate when the string tstr appears in decoding output or the input ends on the PV of the ssv. The value which the offset points will be modified to the last input position on the ssv.

Returns TRUE if the terminator was found, else returns FALSE.

        bool    sv_cat_decode(SV* dsv, SV *encoding, SV *ssv, int *offset, char* tstr, int tlen)
The encoding is assumed to be an Encode object, on entry the PV of the sv is assumed to be octets in that encoding, and the sv will be converted into Unicode (and UTF-8).

If the sv already is UTF-8 (or if it is not POK), or if the encoding is not a reference, nothing is done to the sv. If the encoding is not an "Encode::XS" Encoding object, bad things will happen. (See lib/encoding.pm and Encode).

The PV of the sv is returned.

        char*   sv_recode_to_utf8(SV* sv, SV *encoding)
Build to the scalar dsv a displayable version of the scalar sv, the displayable version being at most pvlim bytes long (if longer, the rest is truncated and "..." will be appended).

The flags argument is as in pv_uni_display().

The pointer to the PV of the dsv is returned.

        char*   sv_uni_display(SV *dsv, SV *ssv, STRLEN pvlim, UV flags)
The "p" contains the pointer to the UTF-8 string encoding the character that is being converted.

The "ustrp" is a pointer to the character buffer to put the conversion result to. The "lenp" is a pointer to the length of the result.

The "swashp" is a pointer to the swash to use.

Both the special and normal mappings are stored lib/unicore/To/Foo.pl, and loaded by SWASHNEW, using lib/utf8_heavy.pl. The special (usually, but not always, a multicharacter mapping), is tried first.

The "special" is a string like "utf8::ToSpecLower", which means the hash %utf8::ToSpecLower. The access to the hash is through Perl_to_utf8_case().

The "normal" is a string like "ToLower" which means the swash %utf8::ToLower.

        UV      to_utf8_case(const U8 *p, U8* ustrp, STRLEN *lenp, SV **swashp, const char *normal, const char *special)
Convert the UTF-8 encoded character at p to its foldcase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the foldcase version may be longer than the original character (up to three characters).

The first character of the foldcased version is returned (but note, as explained above, that there may be more.)

        UV      to_utf8_fold(const U8 *p, U8* ustrp, STRLEN *lenp)
Convert the UTF-8 encoded character at p to its lowercase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the lowercase version may be longer than the original character.

The first character of the lowercased version is returned (but note, as explained above, that there may be more.)

        UV      to_utf8_lower(const U8 *p, U8* ustrp, STRLEN *lenp)
Convert the UTF-8 encoded character at p to its titlecase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the titlecase version may be longer than the original character.

The first character of the titlecased version is returned (but note, as explained above, that there may be more.)

        UV      to_utf8_title(const U8 *p, U8* ustrp, STRLEN *lenp)
Convert the UTF-8 encoded character at p to its uppercase version and store that in UTF-8 in ustrp and its length in bytes in lenp. Note that the ustrp needs to be at least UTF8_MAXBYTES_CASE+1 bytes since the uppercase version may be longer than the original character.

The first character of the uppercased version is returned (but note, as explained above, that there may be more.)

        UV      to_utf8_upper(const U8 *p, U8* ustrp, STRLEN *lenp)
flags

Returns the native character value of the first character in the string "s" which is assumed to be in UTF-8 encoding; "retlen" will be set to the length, in bytes, of that character.

Allows length and flags to be passed to low level routine.

        UV      utf8n_to_uvchr(const U8 *s, STRLEN curlen, STRLEN *retlen, U32 flags)
Bottom level UTF-8 decode routine. Returns the Unicode code point value of the first character in the string "s" which is assumed to be in UTF-8 encoding and no longer than "curlen"; "retlen" will be set to the length, in bytes, of that character.

If "s" does not point to a well-formed UTF-8 character, the behaviour is dependent on the value of "flags": if it contains UTF8_CHECK_ONLY, it is assumed that the caller will raise a warning, and this function will silently just set "retlen" to "-1" and return zero. If the "flags" does not contain UTF8_CHECK_ONLY, warnings about malformations will be given, "retlen" will be set to the expected length of the UTF-8 character in bytes, and zero will be returned.

The "flags" can also contain various flags to allow deviations from the strict UTF-8 encoding (see utf8.h).

Most code should use utf8_to_uvchr() rather than call this directly.

        UV      utf8n_to_uvuni(const U8 *s, STRLEN curlen, STRLEN *retlen, U32 flags)
Returns the number of UTF-8 characters between the UTF-8 pointers "a" and "b".

WARNING: use only if you *know* that the pointers point inside the same UTF-8 buffer.

        IV      utf8_distance(const U8 *a, const U8 *b)
Return the UTF-8 pointer "s" displaced by "off" characters, either forward or backward.

WARNING: do not use the following unless you *know* "off" is within the UTF-8 data pointed to by "s" *and* that on entry "s" is aligned on the first byte of character or just after the last byte of a character.

        U8*     utf8_hop(const U8 *s, I32 off)
Return the length of the UTF-8 char encoded string "s" in characters. Stops at "e" (inclusive). If "e < s" or if the scan would end up past "e", croaks. 

        STRLEN  utf8_length(const U8* s, const U8 *e)
Converts a string "s" of length "len" from UTF-8 into native byte encoding. Unlike "bytes_to_utf8", this over-writes the original string, and updates len to contain the new length. Returns zero on failure, setting "len" to -1.

If you need a copy of the string, see "bytes_from_utf8".

NOTE: this function is experimental and may change or be removed without notice.

        U8*     utf8_to_bytes(U8 *s, STRLEN *len)
Returns the native character value of the first character in the string "s" which is assumed to be in UTF-8 encoding; "retlen" will be set to the length, in bytes, of that character.

If "s" does not point to a well-formed UTF-8 character, zero is returned and retlen is set, if possible, to -1.

        UV      utf8_to_uvchr(const U8 *s, STRLEN *retlen)
Returns the Unicode code point of the first character in the string "s" which is assumed to be in UTF-8 encoding; "retlen" will be set to the length, in bytes, of that character.

This function should only be used when the returned UV is considered an index into the Unicode semantic tables (e.g. swashes).

If "s" does not point to a well-formed UTF-8 character, zero is returned and retlen is set, if possible, to -1.

        UV      utf8_to_uvuni(const U8 *s, STRLEN *retlen)
Adds the UTF-8 representation of the Native codepoint "uv" to the end of the string "d"; "d" should be have at least "UTF8_MAXBYTES+1" free bytes available. The return value is the pointer to the byte after the end of the new character. In other words, 

    d = uvchr_to_utf8(d, uv);

is the recommended wide native character-aware way of saying

    *(d++) = uv;
        U8*     uvchr_to_utf8(U8 *d, UV uv)
Adds the UTF-8 representation of the Unicode codepoint "uv" to the end of the string "d"; "d" should be have at least "UTF8_MAXBYTES+1" free bytes available. The return value is the pointer to the byte after the end of the new character. In other words, 

    d = uvuni_to_utf8_flags(d, uv, flags);

or, in most cases,

    d = uvuni_to_utf8(d, uv);

(which is equivalent to)

    d = uvuni_to_utf8_flags(d, uv, 0);

is the recommended Unicode-aware way of saying

    *(d++) = uv;
        U8*     uvuni_to_utf8_flags(U8 *d, UV uv, UV flags)

Variables created by "xsubpp" and "xsubpp" internal functions

Variable which is setup by "xsubpp" to indicate the stack base offset, used by the "ST", "XSprePUSH" and "XSRETURN" macros. The "dMARK" macro must be called prior to setup the "MARK" variable. 

        I32     ax
Variable which is setup by "xsubpp" to indicate the class name for a C++ XS constructor. This is always a "char*". See "THIS". 

        char*   CLASS
Sets up the "ax" variable. This is usually handled automatically by "xsubpp" by calling "dXSARGS". 

                dAX;
Sets up the "ax" variable and stack marker variable "mark". This is usually handled automatically by "xsubpp" by calling "dXSARGS". 

                dAXMARK;
Sets up the "items" variable. This is usually handled automatically by "xsubpp" by calling "dXSARGS". 

                dITEMS;
Sets up the "padoff_du" variable for an XSUB that wishes to use "UNDERBAR". 

                dUNDERBAR;
Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. Sets up the "ax" and "items" variables by calling "dAX" and "dITEMS". This is usually handled automatically by "xsubpp". 

                dXSARGS;
Sets up the "ix" variable for an XSUB which has aliases. This is usually handled automatically by "xsubpp". 

                dXSI32;
Variable which is setup by "xsubpp" to indicate the number of items on the stack. See "Variable-length Parameter Lists" in perlxs. 

        I32     items
Variable which is setup by "xsubpp" to indicate which of an XSUB's aliases was used to invoke it. See "The ALIAS: Keyword" in perlxs. 

        I32     ix
Used by "xsubpp" to hook up XSUBs as Perl subs. Adds Perl prototypes to the subs.
Variable which is setup by "xsubpp" to hold the return value for an XSUB. This is always the proper type for the XSUB. See "The RETVAL Variable" in perlxs. 

        (whatever)      RETVAL
Used to access elements on the XSUB's stack. 

        SV*     ST(int ix)
Variable which is setup by "xsubpp" to designate the object in a C++ XSUB. This is always the proper type for the C++ object. See "CLASS" and "Using XS With C++" in perlxs. 

        (whatever)      THIS
The SV* corresponding to the $_ variable. Works even if there is a lexical $_ in scope.
Macro to declare an XSUB and its C parameter list. This is handled by "xsubpp".
The version identifier for an XS module. This is usually handled automatically by "ExtUtils::MakeMaker". See "XS_VERSION_BOOTCHECK".
Macro to verify that a PM module's $VERSION variable matches the XS module's "XS_VERSION" variable. This is usually handled automatically by "xsubpp". See "The VERSIONCHECK: Keyword" in perlxs. 

                XS_VERSION_BOOTCHECK;

Warning and Dieing

This is the XSUB-writer's interface to Perl's "die" function. Normally call this function the same way you call the C "printf" function. Calling "croak" returns control directly to Perl, sidestepping the normal C order of execution. See "warn".

If you want to throw an exception object, assign the object to $@ and then pass "NULL" to croak():

   errsv = get_sv("@", GV_ADD);
   sv_setsv(errsv, exception_object);
   croak(NULL);
        void    croak(const char* pat, ...)
This is the XSUB-writer's interface to Perl's "warn" function. Call this function the same way you call the C "printf" function. See "croak". 

        void    warn(const char* pat, ...)

AUTHORS

Until May 1997, this document was maintained by Jeff Okamoto <okamoto@corp.hp.com>. It is now maintained as part of Perl itself.

With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, Stephen McCamant, and Gurusamy Sarathy.

API Listing originally by Dean Roehrich <roehrich@cray.com>.

Updated to be autogenerated from comments in the source by Benjamin Stuhl.

SEE ALSO

perlguts(1), perlxs(1), perlxstut(1), perlintern(1)

2017-03-21 perl v5.10.1