remove misleading comment (from M.J.T. Guy)

[p5sagit/p5-mst-13.2.git] / pod / perlapi.pod

=head1 NAME

perlapi - autogenerated documentation for the perl public API

=head1 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 C<PL_>
prefix.  Some macros are provided for compatibility with the older,
unadorned names, but this support may be disabled in a future release.

The listing is alphabetical, case insensitive.

=over 8

=item AvFILL

Same as C<av_len()>.  Deprecated, use C<av_len()> instead.

        int     AvFILL(AV* av)

=item av_clear

Clears an array, making it empty.  Does not free the memory used by the
array itself.

        void    av_clear(AV* ar)

=item av_extend

Pre-extend an array.  The C<key> is the index to which the array should be
extended.

        void    av_extend(AV* ar, I32 key)

=item av_fetch

Returns the SV at the specified index in the array.  The C<key> is the
index.  If C<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 C<SV*>.

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

        SV**    av_fetch(AV* ar, I32 key, I32 lval)

=item av_len

Returns the highest index in the array.  Returns -1 if the array is
empty.

        I32     av_len(AV* ar)

=item av_make

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** svp)

=item av_pop

Pops an SV off the end of the array.  Returns C<&PL_sv_undef> if the array
is empty.

        SV*     av_pop(AV* ar)

=item av_push

Pushes an SV onto the end of the array.  The array will grow automatically
to accommodate the addition.

        void    av_push(AV* ar, SV* val)

=item av_shift

Shifts an SV off the beginning of the array.

        SV*     av_shift(AV* ar)

=item av_store

Stores an SV in an array.  The array index is specified as C<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 C<SV*>.  Note
that the caller is responsible for suitably incrementing the reference
count of C<val> before the call, and decrementing it if the function
returned NULL.

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

        SV**    av_store(AV* ar, I32 key, SV* val)

=item av_undef

Undefines the array.  Frees the memory used by the array itself.

        void    av_undef(AV* ar)

=item av_unshift

Unshift the given number of C<undef> values onto the beginning of the
array.  The array will grow automatically to accommodate the addition.  You
must then use C<av_store> to assign values to these new elements.

        void    av_unshift(AV* ar, I32 num)

=item call_argv

Performs a callback to the specified Perl sub.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

        I32     call_argv(const char* sub_name, I32 flags, char** argv)

=item call_method

Performs a callback to the specified Perl method.  The blessed object must
be on the stack.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

        I32     call_method(const char* methname, I32 flags)

=item call_pv

Performs a callback to the specified Perl sub.  See L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

        I32     call_pv(const char* sub_name, I32 flags)

=item call_sv

Performs a callback to the Perl sub whose name is in the SV.  See
L<perlcall>.

NOTE: the perl_ form of this function is deprecated.

        I32     call_sv(SV* sv, I32 flags)

=item CLASS

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

        char*   CLASS

=item Copy

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

        void    Copy(void* src, void* dest, int nitems, type)

=item croak

This is the XSUB-writer's interface to Perl's C<die> function.  Use this
function the same way you use the C C<printf> function.  See
C<warn>.

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

=item CvSTASH

Returns the stash of the CV.

        HV*     CvSTASH(CV* cv)

=item dMARK

Declare a stack marker variable, C<mark>, for the XSUB.  See C<MARK> and
C<dORIGMARK>.

                dMARK;

=item dORIGMARK

Saves the original stack mark for the XSUB.  See C<ORIGMARK>.

                dORIGMARK;

=item dSP

Declares a local copy of perl's stack pointer for the XSUB, available via
the C<SP> macro.  See C<SP>.

                dSP;

=item dXSARGS

Sets up stack and mark pointers for an XSUB, calling dSP and dMARK.  This
is usually handled automatically by C<xsubpp>.  Declares the C<items>
variable to indicate the number of items on the stack.

                dXSARGS;

=item dXSI32

Sets up the C<ix> variable for an XSUB which has aliases.  This is usually
handled automatically by C<xsubpp>.

                dXSI32;

=item ENTER

Opening bracket on a callback.  See C<LEAVE> and L<perlcall>.

                ENTER;

=item eval_pv

Tells Perl to C<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)

=item eval_sv

Tells Perl to C<eval> the string in the SV.

NOTE: the perl_ form of this function is deprecated.

        I32     eval_sv(SV* sv, I32 flags)

=item EXTEND

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

        void    EXTEND(SP, int nitems)

=item fbm_compile

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)

=item fbm_instr

Returns the location of the SV in the string delimited by C<str> and
C<strend>.  It returns C<Nullch> if the string can't be found.  The C<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* littlesv, U32 flags)

=item FREETMPS

Closing bracket for temporaries on a callback.  See C<SAVETMPS> and
L<perlcall>.

                FREETMPS;

=item get_av

Returns the AV of the specified Perl array.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<create> is not
set 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 create)

=item get_cv

Returns the CV of the specified Perl subroutine.  If C<create> is set and
the Perl subroutine does not exist then it will be declared (which has the
same effect as saying C<sub name;>).  If C<create> is not set and the
subroutine does not exist then NULL is returned.

NOTE: the perl_ form of this function is deprecated.

        CV*     get_cv(const char* name, I32 create)

=item get_hv

Returns the HV of the specified Perl hash.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<create> is not
set 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 create)

=item get_sv

Returns the SV of the specified Perl scalar.  If C<create> is set and the
Perl variable does not exist then it will be created.  If C<create> is not
set 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 create)

=item GIMME

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

        U32     GIMME

=item GIMME_V

The XSUB-writer's equivalent to Perl's C<wantarray>.  Returns C<G_VOID>,
C<G_SCALAR> or C<G_ARRAY> for void, scalar or array context,
respectively.

        U32     GIMME_V

=item GvSV

Return the SV from the GV.

        SV*     GvSV(GV* gv)

=item gv_fetchmeth

Returns the glob with the given C<name> and a defined subroutine or
C<NULL>.  The glob lives in the given C<stash>, or in the stashes
accessible via @ISA and @UNIVERSAL. 

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

This function grants C<"SUPER"> token as a postfix of the stash name. The
GV returned from C<gv_fetchmeth> may be a method cache entry, which is not
visible to Perl code.  So when calling C<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 C<GvCV> macro. 

        GV*     gv_fetchmeth(HV* stash, const char* name, STRLEN len, I32 level)

=item gv_fetchmethod

See L<gv_fetchmethod_autoload>.

        GV*     gv_fetchmethod(HV* stash, const char* name)

=item gv_fetchmethod_autoload

Returns the glob which contains the subroutine to call to invoke the method
on the C<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 C<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 C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload>
with a non-zero C<autoload> parameter. 

These functions grant C<"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 C<gv_fetchmeth> with
C<level==0>.  C<name> should be writable if contains C<':'> or C<'
''>. The warning against passing the GV returned by C<gv_fetchmeth> to
C<call_sv> apply equally to these functions. 

        GV*     gv_fetchmethod_autoload(HV* stash, const char* name, I32 autoload)

=item gv_stashpv

Returns a pointer to the stash for a specified package.  C<name> should
be a valid UTF-8 string.  If C<create> is set then the package will be
created if it does not already exist.  If C<create> is not set and the
package does not exist then NULL is returned.

        HV*     gv_stashpv(const char* name, I32 create)

=item gv_stashsv

Returns a pointer to the stash for a specified package, which must be a
valid UTF-8 string.  See C<gv_stashpv>.

        HV*     gv_stashsv(SV* sv, I32 create)

=item G_ARRAY

Used to indicate array context.  See C<GIMME_V>, C<GIMME> and
L<perlcall>.

=item G_DISCARD

Indicates that arguments returned from a callback should be discarded.  See
L<perlcall>.

=item G_EVAL

Used to force a Perl C<eval> wrapper around a callback.  See
L<perlcall>.

=item G_NOARGS

Indicates that no arguments are being sent to a callback.  See
L<perlcall>.

=item G_SCALAR

Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
L<perlcall>.

=item G_VOID

Used to indicate void context.  See C<GIMME_V> and L<perlcall>.

=item HEf_SVKEY

This flag, used in the length slot of hash entries and magic structures,
specifies the structure contains a C<SV*> pointer where a C<char*> pointer
is to be expected. (For information only--not to be used).

=item HeHASH

Returns the computed hash stored in the hash entry.

        U32     HeHASH(HE* he)

=item HeKEY

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

        void*   HeKEY(HE* he)

=item HeKLEN

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

        STRLEN  HeKLEN(HE* he)

=item HePV

Returns the key slot of the hash entry as a C<char*> value, doing any
necessary dereferencing of possibly C<SV*> keys.  The length of the string
is placed in C<len> (this is a macro, so do I<not> use C<&len>).  If you do
not care about what the length of the key is, you may use the global
variable C<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 C<strlen()> or similar is not a good way to find
the length of hash keys. This is very similar to the C<SvPV()> macro
described elsewhere in this document.

        char*   HePV(HE* he, STRLEN len)

=item HeSVKEY

Returns the key as an C<SV*>, or C<Nullsv> if the hash entry does not
contain an C<SV*> key.

        SV*     HeSVKEY(HE* he)

=item HeSVKEY_force

Returns the key as an C<SV*>.  Will create and return a temporary mortal
C<SV*> if the hash entry contains only a C<char*> key.

        SV*     HeSVKEY_force(HE* he)

=item HeSVKEY_set

Sets the key to a given C<SV*>, taking care to set the appropriate flags to
indicate the presence of an C<SV*> key, and returns the same
C<SV*>.

        SV*     HeSVKEY_set(HE* he, SV* sv)

=item HeVAL

Returns the value slot (type C<SV*>) stored in the hash entry.

        SV*     HeVAL(HE* he)

=item HvNAME

Returns the package name of a stash.  See C<SvSTASH>, C<CvSTASH>.

        char*   HvNAME(HV* stash)

=item hv_clear

Clears a hash, making it empty.

        void    hv_clear(HV* tb)

=item hv_delete

Deletes a key/value pair in the hash.  The value SV is removed from the
hash and returned to the caller.  The C<klen> is the length of the key. 
The C<flags> value will normally be zero; if set to G_DISCARD then NULL
will be returned.

        SV*     hv_delete(HV* tb, const char* key, U32 klen, I32 flags)

=item hv_delete_ent

Deletes a key/value pair in the hash.  The value SV is removed from the
hash and returned to the caller.  The C<flags> value will normally be zero;
if set to G_DISCARD then NULL will be returned.  C<hash> can be a valid
precomputed hash value, or 0 to ask for it to be computed.

        SV*     hv_delete_ent(HV* tb, SV* key, I32 flags, U32 hash)

=item hv_exists

Returns a boolean indicating whether the specified hash key exists.  The
C<klen> is the length of the key.

        bool    hv_exists(HV* tb, const char* key, U32 klen)

=item hv_exists_ent

Returns a boolean indicating whether the specified hash key exists. C<hash>
can be a valid precomputed hash value, or 0 to ask for it to be
computed.

        bool    hv_exists_ent(HV* tb, SV* key, U32 hash)

=item hv_fetch

Returns the SV which corresponds to the specified key in the hash.  The
C<klen> is the length of the key.  If C<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 C<SV*>. 

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

        SV**    hv_fetch(HV* tb, const char* key, U32 klen, I32 lval)

=item hv_fetch_ent

Returns the hash entry which corresponds to the specified key in the hash.
C<hash> must be a valid precomputed hash number for the given C<key>, or 0
if you want the function to compute it.  IF C<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 C<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 L<perlguts/"Understanding the Magic of Tied Hashes and Arrays"> for more
information on how to use this function on tied hashes.

        HE*     hv_fetch_ent(HV* tb, SV* key, I32 lval, U32 hash)

=item hv_iterinit

Prepares a starting point to traverse a hash table.  Returns the number of
keys in the hash (i.e. the same as C<HvKEYS(tb)>).  The return value is
currently only meaningful for hashes without tie magic. 

NOTE: Before version 5.004_65, C<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 C<HvFILL(tb)>.

        I32     hv_iterinit(HV* tb)

=item hv_iterkey

Returns the key from the current position of the hash iterator.  See
C<hv_iterinit>.

        char*   hv_iterkey(HE* entry, I32* retlen)

=item hv_iterkeysv

Returns the key as an C<SV*> from the current position of the hash
iterator.  The return value will always be a mortal copy of the key.  Also
see C<hv_iterinit>.

        SV*     hv_iterkeysv(HE* entry)

=item hv_iternext

Returns entries from a hash iterator.  See C<hv_iterinit>.

        HE*     hv_iternext(HV* tb)

=item hv_iternextsv

Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one
operation.

        SV*     hv_iternextsv(HV* hv, char** key, I32* retlen)

=item hv_iterval

Returns the value from the current position of the hash iterator.  See
C<hv_iterkey>.

        SV*     hv_iterval(HV* tb, HE* entry)

=item hv_magic

Adds magic to a hash.  See C<sv_magic>.

        void    hv_magic(HV* hv, GV* gv, int how)

=item hv_store

Stores an SV in a hash.  The hash key is specified as C<key> and C<klen> is
the length of the key.  The C<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 C<SV*>.  Note that the caller is
responsible for suitably incrementing the reference count of C<val> before
the call, and decrementing it if the function returned NULL.  

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

        SV**    hv_store(HV* tb, const char* key, U32 klen, SV* val, U32 hash)

=item hv_store_ent

Stores C<val> in a hash.  The hash key is specified as C<key>.  The C<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 C<He???> macros
described here.  Note that the caller is responsible for suitably
incrementing the reference count of C<val> before the call, and
decrementing it if the function returned NULL. 

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

        HE*     hv_store_ent(HV* tb, SV* key, SV* val, U32 hash)

=item hv_undef

Undefines the hash.

        void    hv_undef(HV* tb)

=item isALNUM

Returns a boolean indicating whether the C C<char> is an ASCII alphanumeric
character or digit.

        bool    isALNUM(char ch)

=item isALPHA

Returns a boolean indicating whether the C C<char> is an ASCII alphabetic
character.

        bool    isALPHA(char ch)

=item isDIGIT

Returns a boolean indicating whether the C C<char> is an ASCII
digit.

        bool    isDIGIT(char ch)

=item isLOWER

Returns a boolean indicating whether the C C<char> is a lowercase
character.

        bool    isLOWER(char ch)

=item isSPACE

Returns a boolean indicating whether the C C<char> is whitespace.

        bool    isSPACE(char ch)

=item isUPPER

Returns a boolean indicating whether the C C<char> is an uppercase
character.

        bool    isUPPER(char ch)

=item items

Variable which is setup by C<xsubpp> to indicate the number of 
items on the stack.  See L<perlxs/"Variable-length Parameter Lists">.

        I32     items

=item ix

Variable which is setup by C<xsubpp> to indicate which of an 
XSUB's aliases was used to invoke it.  See L<perlxs/"The ALIAS: Keyword">.

        I32     ix

=item LEAVE

Closing bracket on a callback.  See C<ENTER> and L<perlcall>.

                LEAVE;

=item looks_like_number

Test if an the content of an SV looks like a number (or is a
number).

        I32     looks_like_number(SV* sv)

=item MARK

Stack marker variable for the XSUB.  See C<dMARK>.

=item mg_clear

Clear something magical that the SV represents.  See C<sv_magic>.

        int     mg_clear(SV* sv)

=item mg_copy

Copies the magic from one SV to another.  See C<sv_magic>.

        int     mg_copy(SV* sv, SV* nsv, const char* key, I32 klen)

=item mg_find

Finds the magic pointer for type matching the SV.  See C<sv_magic>.

        MAGIC*  mg_find(SV* sv, int type)

=item mg_free

Free any magic storage used by the SV.  See C<sv_magic>.

        int     mg_free(SV* sv)

=item mg_get

Do magic after a value is retrieved from the SV.  See C<sv_magic>.

        int     mg_get(SV* sv)

=item mg_length

Report on the SV's length.  See C<sv_magic>.

        U32     mg_length(SV* sv)

=item mg_magical

Turns on the magical status of an SV.  See C<sv_magic>.

        void    mg_magical(SV* sv)

=item mg_set

Do magic after a value is assigned to the SV.  See C<sv_magic>.

        int     mg_set(SV* sv)

=item Move

The XSUB-writer's interface to the C C<memmove> function.  The C<src> is the
source, C<dest> is the destination, C<nitems> is the number of items, and C<type> is
the type.  Can do overlapping moves.  See also C<Copy>.

        void    Move(void* src, void* dest, int nitems, type)

=item New

The XSUB-writer's interface to the C C<malloc> function.

        void    New(int id, void* ptr, int nitems, type)

=item newAV

Creates a new AV.  The reference count is set to 1.

        AV*     newAV()

=item Newc

The XSUB-writer's interface to the C C<malloc> function, with
cast.

        void    Newc(int id, void* ptr, int nitems, type, cast)

=item newCONSTSUB

Creates a constant sub equivalent to Perl C<sub FOO () { 123 }> which is
eligible for inlining at compile-time.

        void    newCONSTSUB(HV* stash, char* name, SV* sv)

=item newHV

Creates a new HV.  The reference count is set to 1.

        HV*     newHV()

=item newRV_inc

Creates an RV wrapper for an SV.  The reference count for the original SV is
incremented.

        SV*     newRV_inc(SV* sv)

=item newRV_noinc

Creates an RV wrapper for an SV.  The reference count for the original
SV is B<not> incremented.

        SV*     newRV_noinc(SV *sv)

=item NEWSV

Creates a new SV.  A non-zero C<len> parameter indicates the number of
bytes of preallocated string space the SV should have.  An extra byte for a
tailing 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. 
C<id> is an integer id between 0 and 1299 (used to identify leaks).

        SV*     NEWSV(int id, STRLEN len)

=item newSViv

Creates a new SV and copies an integer into it.  The reference count for the
SV is set to 1.

        SV*     newSViv(IV i)

=item newSVnv

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)

=item newSVpv

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

        SV*     newSVpv(const char* s, STRLEN len)

=item newSVpvf

Creates a new SV an initialize it with the string formatted like
C<sprintf>.

        SV*     newSVpvf(const char* pat, ...)

=item newSVpvn

Creates a new SV and copies a string into it.  The reference count for the
SV is set to 1.  Note that if C<len> is zero, Perl will create a zero length 
string.  You are responsible for ensuring that the source string is at least
C<len> bytes long.

        SV*     newSVpvn(const char* s, STRLEN len)

=item newSVrv

Creates a new SV for the RV, C<rv>, to point to.  If C<rv> is not an RV then
it will be upgraded to one.  If C<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)

=item newSVsv

Creates a new SV which is an exact duplicate of the original SV.

        SV*     newSVsv(SV* old)

=item newSVuv

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)

=item newXS

Used by C<xsubpp> to hook up XSUBs as Perl subs.

=item newXSproto

Used by C<xsubpp> to hook up XSUBs as Perl subs.  Adds Perl prototypes to
the subs.

=item Newz

The XSUB-writer's interface to the C C<malloc> function.  The allocated
memory is zeroed with C<memzero>.

        void    Newz(int id, void* ptr, int nitems, type)

=item Nullav

Null AV pointer.

=item Nullch

Null character pointer.

=item Nullcv

Null CV pointer.

=item Nullhv

Null HV pointer.

=item Nullsv

Null SV pointer.

=item ORIGMARK

The original stack mark for the XSUB.  See C<dORIGMARK>.

=item perl_alloc

Allocates a new Perl interpreter.  See L<perlembed>.

        PerlInterpreter*        perl_alloc()

=item perl_construct

Initializes a new Perl interpreter.  See L<perlembed>.

        void    perl_construct(PerlInterpreter* interp)

=item perl_destruct

Shuts down a Perl interpreter.  See L<perlembed>.

        void    perl_destruct(PerlInterpreter* interp)

=item perl_free

Releases a Perl interpreter.  See L<perlembed>.

        void    perl_free(PerlInterpreter* interp)

=item perl_parse

Tells a Perl interpreter to parse a Perl script.  See L<perlembed>.

        int     perl_parse(PerlInterpreter* interp, XSINIT_t xsinit, int argc, char** argv, char** env)

=item perl_run

Tells a Perl interpreter to run.  See L<perlembed>.

        int     perl_run(PerlInterpreter* interp)

=item PL_DBsingle

When Perl is run in debugging mode, with the B<-d> switch, this SV is a
boolean which indicates whether subs are being single-stepped. 
Single-stepping is automatically turned on after every step.  This is the C
variable which corresponds to Perl's $DB::single variable.  See
C<PL_DBsub>.

        SV *    PL_DBsingle

=item PL_DBsub

When Perl is run in debugging mode, with the B<-d> switch, this GV contains
the SV which holds the name of the sub being debugged.  This is the C
variable which corresponds to Perl's $DB::sub variable.  See
C<PL_DBsingle>.

        GV *    PL_DBsub

=item PL_DBtrace

Trace variable used when Perl is run in debugging mode, with the B<-d>
switch.  This is the C variable which corresponds to Perl's $DB::trace
variable.  See C<PL_DBsingle>.

        SV *    PL_DBtrace

=item PL_dowarn

The C variable which corresponds to Perl's $^W warning variable.

        bool    PL_dowarn

=item PL_modglobal

C<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

=item PL_na

A convenience variable which is typically used with C<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
C<SvPV_nolen> macro.

        STRLEN  PL_na

=item PL_sv_no

This is the C<false> SV.  See C<PL_sv_yes>.  Always refer to this as
C<&PL_sv_no>.

        SV      PL_sv_no

=item PL_sv_undef

This is the C<undef> SV.  Always refer to this as C<&PL_sv_undef>.

        SV      PL_sv_undef

=item PL_sv_yes

This is the C<true> SV.  See C<PL_sv_no>.  Always refer to this as
C<&PL_sv_yes>.

        SV      PL_sv_yes

=item POPi

Pops an integer off the stack.

        IV      POPi

=item POPl

Pops a long off the stack.

        long    POPl

=item POPn

Pops a double off the stack.

        NV      POPn

=item POPp

Pops a string off the stack.

        char*   POPp

=item POPs

Pops an SV off the stack.

        SV*     POPs

=item PUSHi

Push an integer onto the stack.  The stack must have room for this element.
Handles 'set' magic.  See C<XPUSHi>.

        void    PUSHi(IV iv)

=item PUSHMARK

Opening bracket for arguments on a callback.  See C<PUTBACK> and
L<perlcall>.

                PUSHMARK;

=item PUSHn

Push a double onto the stack.  The stack must have room for this element.
Handles 'set' magic.  See C<XPUSHn>.

        void    PUSHn(NV nv)

=item PUSHp

Push a string onto the stack.  The stack must have room for this element.
The C<len> indicates the length of the string.  Handles 'set' magic.  See
C<XPUSHp>.

        void    PUSHp(char* str, STRLEN len)

=item PUSHs

Push an SV onto the stack.  The stack must have room for this element. 
Does not handle 'set' magic.  See C<XPUSHs>.

        void    PUSHs(SV* sv)

=item PUSHu

Push an unsigned integer onto the stack.  The stack must have room for this
element.  See C<XPUSHu>.

        void    PUSHu(UV uv)

=item PUTBACK

Closing bracket for XSUB arguments.  This is usually handled by C<xsubpp>.
See C<PUSHMARK> and L<perlcall> for other uses.

                PUTBACK;

=item Renew

The XSUB-writer's interface to the C C<realloc> function.

        void    Renew(void* ptr, int nitems, type)

=item Renewc

The XSUB-writer's interface to the C C<realloc> function, with
cast.

        void    Renewc(void* ptr, int nitems, type, cast)

=item require_pv

Tells Perl to C<require> a module.

NOTE: the perl_ form of this function is deprecated.

        void    require_pv(const char* pv)

=item RETVAL

Variable which is setup by C<xsubpp> to hold the return value for an 
XSUB. This is always the proper type for the XSUB. See 
L<perlxs/"The RETVAL Variable">.

        (whatever)      RETVAL

=item Safefree

The XSUB-writer's interface to the C C<free> function.

        void    Safefree(void* src, void* dest, int nitems, type)

=item savepv

Copy a string to a safe spot.  This does not use an SV.

        char*   savepv(const char* sv)

=item savepvn

Copy a string to a safe spot.  The C<len> indicates number of bytes to
copy.  This does not use an SV.

        char*   savepvn(const char* sv, I32 len)

=item SAVETMPS

Opening bracket for temporaries on a callback.  See C<FREETMPS> and
L<perlcall>.

                SAVETMPS;

=item SP

Stack pointer.  This is usually handled by C<xsubpp>.  See C<dSP> and
C<SPAGAIN>.

=item SPAGAIN

Refetch the stack pointer.  Used after a callback.  See L<perlcall>.

                SPAGAIN;

=item ST

Used to access elements on the XSUB's stack.

        SV*     ST(int ix)

=item strEQ

Test two strings to see if they are equal.  Returns true or false.

        bool    strEQ(char* s1, char* s2)

=item strGE

Test two strings to see if the first, C<s1>, is greater than or equal to
the second, C<s2>.  Returns true or false.

        bool    strGE(char* s1, char* s2)

=item strGT

Test two strings to see if the first, C<s1>, is greater than the second,
C<s2>.  Returns true or false.

        bool    strGT(char* s1, char* s2)

=item strLE

Test two strings to see if the first, C<s1>, is less than or equal to the
second, C<s2>.  Returns true or false.

        bool    strLE(char* s1, char* s2)

=item strLT

Test two strings to see if the first, C<s1>, is less than the second,
C<s2>.  Returns true or false.

        bool    strLT(char* s1, char* s2)

=item strNE

Test two strings to see if they are different.  Returns true or
false.

        bool    strNE(char* s1, char* s2)

=item strnEQ

Test two strings to see if they are equal.  The C<len> parameter indicates
the number of bytes to compare.  Returns true or false. (A wrapper for
C<strncmp>).

        bool    strnEQ(char* s1, char* s2, STRLEN len)

=item strnNE

Test two strings to see if they are different.  The C<len> parameter
indicates the number of bytes to compare.  Returns true or false. (A
wrapper for C<strncmp>).

        bool    strnNE(char* s1, char* s2, STRLEN len)

=item StructCopy

This is an architecture-independent macro to copy one structure to another.

        void    StructCopy(type src, type dest, type)

=item SvCUR

Returns the length of the string which is in the SV.  See C<SvLEN>.

        STRLEN  SvCUR(SV* sv)

=item SvCUR_set

Set the length of the string which is in the SV.  See C<SvCUR>.

        void    SvCUR_set(SV* sv, STRLEN len)

=item SvEND

Returns a pointer to the last character in the string which is in the SV.
See C<SvCUR>.  Access the character as *(SvEND(sv)).

        char*   SvEND(SV* sv)

=item SvGETMAGIC

Invokes C<mg_get> on an SV if it has 'get' magic.  This macro evaluates its
argument more than once.

        void    SvGETMAGIC(SV* sv)

=item SvGROW

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 C<sv_grow> to perform the expansion if necessary. 
Returns a pointer to the character buffer.

        void    SvGROW(SV* sv, STRLEN len)

=item SvIOK

Returns a boolean indicating whether the SV contains an integer.

        bool    SvIOK(SV* sv)

=item SvIOKp

Returns a boolean indicating whether the SV contains an integer.  Checks
the B<private> setting.  Use C<SvIOK>.

        bool    SvIOKp(SV* sv)

=item SvIOK_off

Unsets the IV status of an SV.

        void    SvIOK_off(SV* sv)

=item SvIOK_on

Tells an SV that it is an integer.

        void    SvIOK_on(SV* sv)

=item SvIOK_only

Tells an SV that it is an integer and disables all other OK bits.

        void    SvIOK_only(SV* sv)

=item SvIV

Coerces the given SV to an integer and returns it.

        IV      SvIV(SV* sv)

=item SvIVX

Returns the integer which is stored in the SV, assuming SvIOK is
true.

        IV      SvIVX(SV* sv)

=item SvLEN

Returns the size of the string buffer in the SV.  See C<SvCUR>.

        STRLEN  SvLEN(SV* sv)

=item SvNIOK

Returns a boolean indicating whether the SV contains a number, integer or
double.

        bool    SvNIOK(SV* sv)

=item SvNIOKp

Returns a boolean indicating whether the SV contains a number, integer or
double.  Checks the B<private> setting.  Use C<SvNIOK>.

        bool    SvNIOKp(SV* sv)

=item SvNIOK_off

Unsets the NV/IV status of an SV.

        void    SvNIOK_off(SV* sv)

=item SvNOK

Returns a boolean indicating whether the SV contains a double.

        bool    SvNOK(SV* sv)

=item SvNOKp

Returns a boolean indicating whether the SV contains a double.  Checks the
B<private> setting.  Use C<SvNOK>.

        bool    SvNOKp(SV* sv)

=item SvNOK_off

Unsets the NV status of an SV.

        void    SvNOK_off(SV* sv)

=item SvNOK_on

Tells an SV that it is a double.

        void    SvNOK_on(SV* sv)

=item SvNOK_only

Tells an SV that it is a double and disables all other OK bits.

        void    SvNOK_only(SV* sv)

=item SvNV

Coerce the given SV to a double and return it.

        NV      SvNV(SV* sv)

=item SvNVX

Returns the double which is stored in the SV, assuming SvNOK is
true.

        NV      SvNVX(SV* sv)

=item SvOK

Returns a boolean indicating whether the value is an SV.

        bool    SvOK(SV* sv)

=item SvOOK

Returns a boolean 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).

        bool    SvOOK(SV* sv)

=item SvPOK

Returns a boolean indicating whether the SV contains a character
string.

        bool    SvPOK(SV* sv)

=item SvPOKp

Returns a boolean indicating whether the SV contains a character string.
Checks the B<private> setting.  Use C<SvPOK>.

        bool    SvPOKp(SV* sv)

=item SvPOK_off

Unsets the PV status of an SV.

        void    SvPOK_off(SV* sv)

=item SvPOK_on

Tells an SV that it is a string.

        void    SvPOK_on(SV* sv)

=item SvPOK_only

Tells an SV that it is a string and disables all other OK bits.

        void    SvPOK_only(SV* sv)

=item SvPV

Returns a pointer to the string in the SV, or a stringified form of the SV
if the SV does not contain a string.  Handles 'get' magic.

        char*   SvPV(SV* sv, STRLEN len)

=item SvPVX

Returns a pointer to the string in the SV.  The SV must contain a
string.

        char*   SvPVX(SV* sv)

=item SvPV_force

Like <SvPV> but will force the SV into becoming a string (SvPOK).  You want
force if you are going to update the SvPVX directly.

        char*   SvPV_force(SV* sv, STRLEN len)

=item SvPV_nolen

Returns a pointer to the string in the SV, or a stringified form of the SV
if the SV does not contain a string.  Handles 'get' magic.

        char*   SvPV_nolen(SV* sv)

=item SvREFCNT

Returns the value of the object's reference count.

        U32     SvREFCNT(SV* sv)

=item SvREFCNT_dec

Decrements the reference count of the given SV.

        void    SvREFCNT_dec(SV* sv)

=item SvREFCNT_inc

Increments the reference count of the given SV.

        SV*     SvREFCNT_inc(SV* sv)

=item SvROK

Tests if the SV is an RV.

        bool    SvROK(SV* sv)

=item SvROK_off

Unsets the RV status of an SV.

        void    SvROK_off(SV* sv)

=item SvROK_on

Tells an SV that it is an RV.

        void    SvROK_on(SV* sv)

=item SvRV

Dereferences an RV to return the SV.

        SV*     SvRV(SV* sv)

=item SvSETMAGIC

Invokes C<mg_set> on an SV if it has 'set' magic.  This macro evaluates its
argument more than once.

        void    SvSETMAGIC(SV* sv)

=item SvSetSV

Calls C<sv_setsv> if dsv is not the same as ssv.  May evaluate arguments
more than once.

        void    SvSetSV(SV* dsb, SV* ssv)

=item SvSetSV_nosteal

Calls a non-destructive version of C<sv_setsv> if dsv is not the same as
ssv. May evaluate arguments more than once.

        void    SvSetSV_nosteal(SV* dsv, SV* ssv)

=item SvSTASH

Returns the stash of the SV.

        HV*     SvSTASH(SV* sv)

=item SvTAINT

Taints an SV if tainting is enabled

        void    SvTAINT(SV* sv)

=item SvTAINTED

Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if
not.

        bool    SvTAINTED(SV* sv)

=item SvTAINTED_off

Untaints an SV. Be I<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)

=item SvTAINTED_on

Marks an SV as tainted.

        void    SvTAINTED_on(SV* sv)

=item SvTRUE

Returns a boolean indicating whether Perl would evaluate the SV as true or
false, defined or undefined.  Does not handle 'get' magic.

        bool    SvTRUE(SV* sv)

=item SvTYPE

Returns the type of the SV.  See C<svtype>.

        svtype  SvTYPE(SV* sv)

=item svtype

An enum of flags for Perl types.  These are found in the file B<sv.h> 
in the C<svtype> enum.  Test these flags with the C<SvTYPE> macro.

=item SVt_IV

Integer type flag for scalars.  See C<svtype>.

=item SVt_NV

Double type flag for scalars.  See C<svtype>.

=item SVt_PV

Pointer type flag for scalars.  See C<svtype>.

=item SVt_PVAV

Type flag for arrays.  See C<svtype>.

=item SVt_PVCV

Type flag for code refs.  See C<svtype>.

=item SVt_PVHV

Type flag for hashes.  See C<svtype>.

=item SVt_PVMG

Type flag for blessed scalars.  See C<svtype>.

=item SvUPGRADE

Used to upgrade an SV to a more complex form.  Uses C<sv_upgrade> to
perform the upgrade if necessary.  See C<svtype>.

        void    SvUPGRADE(SV* sv, svtype type)

=item SvUV

Coerces the given SV to an unsigned integer and returns it.

        UV      SvUV(SV* sv)

=item SvUVX

Returns the unsigned integer which is stored in the SV, assuming SvIOK is
true.

        UV      SvUVX(SV* sv)

=item sv_2mortal

Marks an SV as mortal.  The SV will be destroyed when the current context
ends.

        SV*     sv_2mortal(SV* sv)

=item sv_bless

Blesses an SV into a specified package.  The SV must be an RV.  The package
must be designated by its stash (see C<gv_stashpv()>).  The reference count
of the SV is unaffected.

        SV*     sv_bless(SV* sv, HV* stash)

=item sv_catpv

Concatenates the string onto the end of the string which is in the SV.
Handles 'get' magic, but not 'set' magic.  See C<sv_catpv_mg>.

        void    sv_catpv(SV* sv, const char* ptr)

=item sv_catpvf

Processes its arguments like C<sprintf> and appends the formatted output
to an SV.  Handles 'get' magic, but not 'set' magic.  C<SvSETMAGIC()> must
typically be called after calling this function to handle 'set' magic.

        void    sv_catpvf(SV* sv, const char* pat, ...)

=item sv_catpvf_mg

Like C<sv_catpvf>, but also handles 'set' magic.

        void    sv_catpvf_mg(SV *sv, const char* pat, ...)

=item sv_catpvn

Concatenates the string onto the end of the string which is in the SV.  The
C<len> indicates number of bytes to copy.  Handles 'get' magic, but not
'set' magic.  See C<sv_catpvn_mg>.

        void    sv_catpvn(SV* sv, const char* ptr, STRLEN len)

=item sv_catpvn_mg

Like C<sv_catpvn>, but also handles 'set' magic.

        void    sv_catpvn_mg(SV *sv, const char *ptr, STRLEN len)

=item sv_catpv_mg

Like C<sv_catpv>, but also handles 'set' magic.

        void    sv_catpv_mg(SV *sv, const char *ptr)

=item sv_catsv

Concatenates the string from SV C<ssv> onto the end of the string in SV
C<dsv>.  Handles 'get' magic, but not 'set' magic.  See C<sv_catsv_mg>.

        void    sv_catsv(SV* dsv, SV* ssv)

=item sv_catsv_mg

Like C<sv_catsv>, but also handles 'set' magic.

        void    sv_catsv_mg(SV *dstr, SV *sstr)

=item sv_chop

Efficient removal of characters from the beginning of the string buffer. 
SvPOK(sv) must be true and the C<ptr> must be a pointer to somewhere inside
the string buffer.  The C<ptr> becomes the first character of the adjusted
string.

        void    sv_chop(SV* sv, char* ptr)

=item sv_cmp

Compares the strings in two SVs.  Returns -1, 0, or 1 indicating whether the
string in C<sv1> is less than, equal to, or greater than the string in
C<sv2>.

        I32     sv_cmp(SV* sv1, SV* sv2)

=item sv_dec

Auto-decrement of the value in the SV.

        void    sv_dec(SV* sv)

=item sv_derived_from

Returns a boolean indicating whether the SV is derived from the specified
class.  This is the function that implements C<UNIVERSAL::isa>.  It works
for class names as well as for objects.

        bool    sv_derived_from(SV* sv, const char* name)

=item sv_eq

Returns a boolean indicating whether the strings in the two SVs are
identical.

        I32     sv_eq(SV* sv1, SV* sv2)

=item sv_grow

Expands the character buffer in the SV.  This will use C<sv_unref> and will
upgrade the SV to C<SVt_PV>.  Returns a pointer to the character buffer.
Use C<SvGROW>.

        char*   sv_grow(SV* sv, STRLEN newlen)

=item sv_inc

Auto-increment of the value in the SV.

        void    sv_inc(SV* sv)

=item sv_insert

Inserts a string at the specified offset/length within the SV. Similar to
the Perl substr() function.

        void    sv_insert(SV* bigsv, STRLEN offset, STRLEN len, char* little, STRLEN littlelen)

=item sv_isa

Returns a boolean indicating whether the SV is blessed into the specified
class.  This does not check for subtypes; use C<sv_derived_from> to verify
an inheritance relationship.

        int     sv_isa(SV* sv, const char* name)

=item sv_isobject

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)

=item sv_len

Returns the length of the string in the SV.  See also C<SvCUR>.

        STRLEN  sv_len(SV* sv)

=item sv_magic

Adds magic to an SV.

        void    sv_magic(SV* sv, SV* obj, int how, const char* name, I32 namlen)

=item sv_mortalcopy

Creates a new SV which is a copy of the original SV.  The new SV is marked
as mortal.

        SV*     sv_mortalcopy(SV* oldsv)

=item sv_newmortal

Creates a new SV which is mortal.  The reference count of the SV is set to 1.

        SV*     sv_newmortal()

=item sv_setiv

Copies an integer into the given SV.  Does not handle 'set' magic.  See
C<sv_setiv_mg>.

        void    sv_setiv(SV* sv, IV num)

=item sv_setiv_mg

Like C<sv_setiv>, but also handles 'set' magic.

        void    sv_setiv_mg(SV *sv, IV i)

=item sv_setnv

Copies a double into the given SV.  Does not handle 'set' magic.  See
C<sv_setnv_mg>.

        void    sv_setnv(SV* sv, NV num)

=item sv_setnv_mg

Like C<sv_setnv>, but also handles 'set' magic.

        void    sv_setnv_mg(SV *sv, NV num)

=item sv_setpv

Copies a string into an SV.  The string must be null-terminated.  Does not
handle 'set' magic.  See C<sv_setpv_mg>.

        void    sv_setpv(SV* sv, const char* ptr)

=item sv_setpvf

Processes its arguments like C<sprintf> and sets an SV to the formatted
output.  Does not handle 'set' magic.  See C<sv_setpvf_mg>.

        void    sv_setpvf(SV* sv, const char* pat, ...)

=item sv_setpvf_mg

Like C<sv_setpvf>, but also handles 'set' magic.

        void    sv_setpvf_mg(SV *sv, const char* pat, ...)

=item sv_setpviv

Copies an integer into the given SV, also updating its string value.
Does not handle 'set' magic.  See C<sv_setpviv_mg>.

        void    sv_setpviv(SV* sv, IV num)

=item sv_setpviv_mg

Like C<sv_setpviv>, but also handles 'set' magic.

        void    sv_setpviv_mg(SV *sv, IV iv)

=item sv_setpvn

Copies a string into an SV.  The C<len> parameter indicates the number of
bytes to be copied.  Does not handle 'set' magic.  See C<sv_setpvn_mg>.

        void    sv_setpvn(SV* sv, const char* ptr, STRLEN len)

=item sv_setpvn_mg

Like C<sv_setpvn>, but also handles 'set' magic.

        void    sv_setpvn_mg(SV *sv, const char *ptr, STRLEN len)

=item sv_setpv_mg

Like C<sv_setpv>, but also handles 'set' magic.

        void    sv_setpv_mg(SV *sv, const char *ptr)

=item sv_setref_iv

Copies an integer into a new SV, optionally blessing the SV.  The C<rv>
argument will be upgraded to an RV.  That RV will be modified to point to
the new SV.  The C<classname> argument indicates the package for the
blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
will be returned and will have a reference count of 1.

        SV*     sv_setref_iv(SV* rv, const char* classname, IV iv)

=item sv_setref_nv

Copies a double into a new SV, optionally blessing the SV.  The C<rv>
argument will be upgraded to an RV.  That RV will be modified to point to
the new SV.  The C<classname> argument indicates the package for the
blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
will be returned and will have a reference count of 1.

        SV*     sv_setref_nv(SV* rv, const char* classname, NV nv)

=item sv_setref_pv

Copies a pointer into a new SV, optionally blessing the SV.  The C<rv>
argument will be upgraded to an RV.  That RV will be modified to point to
the new SV.  If the C<pv> argument is NULL then C<PL_sv_undef> will be placed
into the SV.  The C<classname> argument indicates the package for the
blessing.  Set C<classname> to C<Nullch> to avoid the blessing.  The new SV
will be returned and will have a reference count of 1.

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 C<sv_setref_pvn> copies the string while this copies the pointer.

        SV*     sv_setref_pv(SV* rv, const char* classname, void* pv)

=item sv_setref_pvn

Copies a string into a new SV, optionally blessing the SV.  The length of the
string must be specified with C<n>.  The C<rv> argument will be upgraded to
an RV.  That RV will be modified to point to the new SV.  The C<classname>
argument indicates the package for the blessing.  Set C<classname> to
C<Nullch> to avoid the blessing.  The new SV will be returned and will have
a reference count of 1.

Note that C<sv_setref_pv> copies the pointer while this copies the string.

        SV*     sv_setref_pvn(SV* rv, const char* classname, char* pv, STRLEN n)

=item sv_setsv

Copies the contents of the source SV C<ssv> into the destination SV C<dsv>.
The source SV may be destroyed if it is mortal.  Does not handle 'set'
magic.  See the macro forms C<SvSetSV>, C<SvSetSV_nosteal> and
C<sv_setsv_mg>.

        void    sv_setsv(SV* dsv, SV* ssv)

=item sv_setsv_mg

Like C<sv_setsv>, but also handles 'set' magic.

        void    sv_setsv_mg(SV *dstr, SV *sstr)

=item sv_setuv

Copies an unsigned integer into the given SV.  Does not handle 'set' magic.
See C<sv_setuv_mg>.

        void    sv_setuv(SV* sv, UV num)

=item sv_setuv_mg

Like C<sv_setuv>, but also handles 'set' magic.

        void    sv_setuv_mg(SV *sv, UV u)

=item sv_unref

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 C<newSVrv>.  See C<SvROK_off>.

        void    sv_unref(SV* sv)

=item sv_upgrade

Upgrade an SV to a more complex form.  Use C<SvUPGRADE>.  See
C<svtype>.

        bool    sv_upgrade(SV* sv, U32 mt)

=item sv_usepvn

Tells an SV to use C<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 C<ptr> should point to memory that was allocated by C<malloc>.  The
string length, C<len>, must be supplied.  This function will realloc the
memory pointed to by C<ptr>, so that pointer should not be freed or used by
the programmer after giving it to sv_usepvn.  Does not handle 'set' magic.
See C<sv_usepvn_mg>.

        void    sv_usepvn(SV* sv, char* ptr, STRLEN len)

=item sv_usepvn_mg

Like C<sv_usepvn>, but also handles 'set' magic.

        void    sv_usepvn_mg(SV *sv, char *ptr, STRLEN len)

=item sv_vcatpvfn

Processes its arguments like C<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
C<maybe_tainted> if results are untrustworthy (often due to the use of
locales).

        void    sv_vcatpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)

=item sv_vsetpvfn

Works like C<vcatpvfn> but copies the text into the SV instead of
appending it.

        void    sv_vsetpvfn(SV* sv, const char* pat, STRLEN patlen, va_list* args, SV** svargs, I32 svmax, bool *maybe_tainted)

=item THIS

Variable which is setup by C<xsubpp> to designate the object in a C++ 
XSUB.  This is always the proper type for the C++ object.  See C<CLASS> and 
L<perlxs/"Using XS With C++">.

        (whatever)      THIS

=item toLOWER

Converts the specified character to lowercase.

        char    toLOWER(char ch)

=item toUPPER

Converts the specified character to uppercase.

        char    toUPPER(char ch)

=item warn

This is the XSUB-writer's interface to Perl's C<warn> function.  Use this
function the same way you use the C C<printf> function.  See
C<croak>.

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

=item XPUSHi

Push an integer onto the stack, extending the stack if necessary.  Handles
'set' magic. See C<PUSHi>.

        void    XPUSHi(IV iv)

=item XPUSHn

Push a double onto the stack, extending the stack if necessary.  Handles
'set' magic.  See C<PUSHn>.

        void    XPUSHn(NV nv)

=item XPUSHp

Push a string onto the stack, extending the stack if necessary.  The C<len>
indicates the length of the string.  Handles 'set' magic.  See
C<PUSHp>.

        void    XPUSHp(char* str, STRLEN len)

=item XPUSHs

Push an SV onto the stack, extending the stack if necessary.  Does not
handle 'set' magic.  See C<PUSHs>.

        void    XPUSHs(SV* sv)

=item XPUSHu

Push an unsigned integer onto the stack, extending the stack if necessary. 
See C<PUSHu>.

        void    XPUSHu(UV uv)

=item XS

Macro to declare an XSUB and its C parameter list.  This is handled by
C<xsubpp>.

=item XSRETURN

Return from XSUB, indicating number of items on the stack.  This is usually
handled by C<xsubpp>.

        void    XSRETURN(int nitems)

=item XSRETURN_EMPTY

Return an empty list from an XSUB immediately.

                XSRETURN_EMPTY;

=item XSRETURN_IV

Return an integer from an XSUB immediately.  Uses C<XST_mIV>.

        void    XSRETURN_IV(IV iv)

=item XSRETURN_NO

Return C<&PL_sv_no> from an XSUB immediately.  Uses C<XST_mNO>.

                XSRETURN_NO;

=item XSRETURN_NV

Return an double from an XSUB immediately.  Uses C<XST_mNV>.

        void    XSRETURN_NV(NV nv)

=item XSRETURN_PV

Return a copy of a string from an XSUB immediately.  Uses C<XST_mPV>.

        void    XSRETURN_PV(char* str)

=item XSRETURN_UNDEF

Return C<&PL_sv_undef> from an XSUB immediately.  Uses C<XST_mUNDEF>.

                XSRETURN_UNDEF;

=item XSRETURN_YES

Return C<&PL_sv_yes> from an XSUB immediately.  Uses C<XST_mYES>.

                XSRETURN_YES;

=item XST_mIV

Place an integer into the specified position C<pos> on the stack.  The
value is stored in a new mortal SV.

        void    XST_mIV(int pos, IV iv)

=item XST_mNO

Place C<&PL_sv_no> into the specified position C<pos> on the
stack.

        void    XST_mNO(int pos)

=item XST_mNV

Place a double into the specified position C<pos> on the stack.  The value
is stored in a new mortal SV.

        void    XST_mNV(int pos, NV nv)

=item XST_mPV

Place a copy of a string into the specified position C<pos> on the stack. 
The value is stored in a new mortal SV.

        void    XST_mPV(int pos, char* str)

=item XST_mUNDEF

Place C<&PL_sv_undef> into the specified position C<pos> on the
stack.

        void    XST_mUNDEF(int pos)

=item XST_mYES

Place C<&PL_sv_yes> into the specified position C<pos> on the
stack.

        void    XST_mYES(int pos)

=item XS_VERSION

The version identifier for an XS module.  This is usually
handled automatically by C<ExtUtils::MakeMaker>.  See C<XS_VERSION_BOOTCHECK>.

=item XS_VERSION_BOOTCHECK

Macro to verify that a PM module's $VERSION variable matches the XS
module's C<XS_VERSION> variable.  This is usually handled automatically by
C<xsubpp>.  See L<perlxs/"The VERSIONCHECK: Keyword">.

                XS_VERSION_BOOTCHECK;

=item Zero

The XSUB-writer's interface to the C C<memzero> function.  The C<dest> is the
destination, C<nitems> is the number of items, and C<type> is the type.

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

=back

=head1 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.

=head1 SEE ALSO

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