3 perlguts - Perl's Internal Functions
7 This document attempts to describe some of the internal functions of the
8 Perl executable. It is far from complete and probably contains many errors.
9 Please refer any questions or comments to the author below.
13 Perl has three typedefs that handle Perl's three main data types:
19 Each typedef has specific routines that manipulate the various data types.
21 =head2 What is an "IV"?
23 Perl uses a special typedef IV which is large enough to hold either an
26 Perl also uses two special typedefs, I32 and I16, which will always be at
27 least 32-bits and 16-bits long, respectively.
29 =head2 Working with SVs
31 An SV can be created and loaded with one command. There are four types of
32 values that can be loaded: an integer value (IV), a double (NV), a string,
33 (PV), and another scalar (SV).
35 The four routines are:
39 SV* newSVpv(char*, int);
42 To change the value of an *already-existing* SV, there are five routines:
44 void sv_setiv(SV*, IV);
45 void sv_setnv(SV*, double);
46 void sv_setpvn(SV*, char*, int)
47 void sv_setpv(SV*, char*);
48 void sv_setsv(SV*, SV*);
50 Notice that you can choose to specify the length of the string to be
51 assigned by using C<sv_setpvn> or C<newSVpv>, or you may allow Perl to
52 calculate the length by using C<sv_setpv> or by specifying 0 as the second
53 argument to C<newSVpv>. Be warned, though, that Perl will determine the
54 string's length by using C<strlen>, which depends on the string terminating
57 To access the actual value that an SV points to, you can use the macros:
63 which will automatically coerce the actual scalar type into an IV, double,
66 In the C<SvPV> macro, the length of the string returned is placed into the
67 variable C<len> (this is a macro, so you do I<not> use C<&len>). If you do not
68 care what the length of the data is, use the global variable C<na>. Remember,
69 however, that Perl allows arbitrary strings of data that may both contain
70 NULs and not be terminated by a NUL.
72 If you simply want to know if the scalar value is TRUE, you can use:
76 Although Perl will automatically grow strings for you, if you need to force
77 Perl to allocate more memory for your SV, you can use the macro
79 SvGROW(SV*, STRLEN newlen)
81 which will determine if more memory needs to be allocated. If so, it will
82 call the function C<sv_grow>. Note that C<SvGROW> can only increase, not
83 decrease, the allocated memory of an SV.
85 If you have an SV and want to know what kind of data Perl thinks is stored
86 in it, you can use the following macros to check the type of SV you have.
92 You can get and set the current length of the string stored in an SV with
96 SvCUR_set(SV*, I32 val)
98 You can also get a pointer to the end of the string stored in the SV
103 But note that these last three macros are valid only if C<SvPOK()> is true.
105 If you want to append something to the end of string stored in an C<SV*>,
106 you can use the following functions:
108 void sv_catpv(SV*, char*);
109 void sv_catpvn(SV*, char*, int);
110 void sv_catsv(SV*, SV*);
112 The first function calculates the length of the string to be appended by
113 using C<strlen>. In the second, you specify the length of the string
114 yourself. The third function extends the string stored in the first SV
115 with the string stored in the second SV. It also forces the second SV to
116 be interpreted as a string.
118 If you know the name of a scalar variable, you can get a pointer to its SV
119 by using the following:
121 SV* perl_get_sv("varname", FALSE);
123 This returns NULL if the variable does not exist.
125 If you want to know if this variable (or any other SV) is actually C<defined>,
130 The scalar C<undef> value is stored in an SV instance called C<sv_undef>. Its
131 address can be used whenever an C<SV*> is needed.
133 There are also the two values C<sv_yes> and C<sv_no>, which contain Boolean
134 TRUE and FALSE values, respectively. Like C<sv_undef>, their addresses can
135 be used whenever an C<SV*> is needed.
137 Do not be fooled into thinking that C<(SV *) 0> is the same as C<&sv_undef>.
141 if (I-am-to-return-a-real-value) {
142 sv = sv_2mortal(newSViv(42));
146 This code tries to return a new SV (which contains the value 42) if it should
147 return a real value, or undef otherwise. Instead it has returned a null
148 pointer which, somewhere down the line, will cause a segmentation violation,
149 or just weird results. Change the zero to C<&sv_undef> in the first line and
152 To free an SV that you've created, call C<SvREFCNT_dec(SV*)>. Normally this
153 call is not necessary. See the section on B<MORTALITY>.
155 =head2 What's Really Stored in an SV?
157 Recall that the usual method of determining the type of scalar you have is
158 to use C<Sv*OK> macros. Since a scalar can be both a number and a string,
159 usually these macros will always return TRUE and calling the C<Sv*V>
160 macros will do the appropriate conversion of string to integer/double or
161 integer/double to string.
163 If you I<really> need to know if you have an integer, double, or string
164 pointer in an SV, you can use the following three macros instead:
170 These will tell you if you truly have an integer, double, or string pointer
171 stored in your SV. The "p" stands for private.
173 In general, though, it's best to just use the C<Sv*V> macros.
175 =head2 Working with AVs
177 There are two ways to create and load an AV. The first method just creates
182 The second method both creates the AV and initially populates it with SVs:
184 AV* av_make(I32 num, SV **ptr);
186 The second argument points to an array containing C<num> C<SV*>s. Once the
187 AV has been created, the SVs can be destroyed, if so desired.
189 Once the AV has been created, the following operations are possible on AVs:
191 void av_push(AV*, SV*);
194 void av_unshift(AV*, I32 num);
196 These should be familiar operations, with the exception of C<av_unshift>.
197 This routine adds C<num> elements at the front of the array with the C<undef>
198 value. You must then use C<av_store> (described below) to assign values
199 to these new elements.
201 Here are some other functions:
203 I32 av_len(AV*); /* Returns highest index value in array */
205 SV** av_fetch(AV*, I32 key, I32 lval);
206 /* Fetches value at key offset, but it stores an undef value
207 at the offset if lval is non-zero */
208 SV** av_store(AV*, I32 key, SV* val);
209 /* Stores val at offset key */
211 Take note that C<av_fetch> and C<av_store> return C<SV**>s, not C<SV*>s.
214 /* Clear out all elements, but leave the array */
216 /* Undefines the array, removing all elements */
217 void av_extend(AV*, I32 key);
218 /* Extend the array to a total of key elements */
220 If you know the name of an array variable, you can get a pointer to its AV
221 by using the following:
223 AV* perl_get_av("varname", FALSE);
225 This returns NULL if the variable does not exist.
227 =head2 Working with HVs
229 To create an HV, you use the following routine:
233 Once the HV has been created, the following operations are possible on HVs:
235 SV** hv_store(HV*, char* key, U32 klen, SV* val, U32 hash);
236 SV** hv_fetch(HV*, char* key, U32 klen, I32 lval);
238 The C<klen> parameter is the length of the key being passed in. The C<val>
239 argument contains the SV pointer to the scalar being stored, and C<hash> is
240 the pre-computed hash value (zero if you want C<hv_store> to calculate it
241 for you). The C<lval> parameter indicates whether this fetch is actually a
242 part of a store operation.
244 Remember that C<hv_store> and C<hv_fetch> return C<SV**>s and not just
245 C<SV*>. In order to access the scalar value, you must first dereference
246 the return value. However, you should check to make sure that the return
247 value is not NULL before dereferencing it.
249 These two functions check if a hash table entry exists, and deletes it.
251 bool hv_exists(HV*, char* key, U32 klen);
252 SV* hv_delete(HV*, char* key, U32 klen, I32 flags);
254 And more miscellaneous functions:
257 /* Clears all entries in hash table */
259 /* Undefines the hash table */
261 Perl keeps the actual data in linked list of structures with a typedef of HE.
262 These contain the actual key and value pointers (plus extra administrative
263 overhead). The key is a string pointer; the value is an C<SV*>. However,
264 once you have an C<HE*>, to get the actual key and value, use the routines
267 I32 hv_iterinit(HV*);
268 /* Prepares starting point to traverse hash table */
269 HE* hv_iternext(HV*);
270 /* Get the next entry, and return a pointer to a
271 structure that has both the key and value */
272 char* hv_iterkey(HE* entry, I32* retlen);
273 /* Get the key from an HE structure and also return
274 the length of the key string */
275 SV* hv_iterval(HV*, HE* entry);
276 /* Return a SV pointer to the value of the HE
278 SV* hv_iternextsv(HV*, char** key, I32* retlen);
279 /* This convenience routine combines hv_iternext,
280 hv_iterkey, and hv_iterval. The key and retlen
281 arguments are return values for the key and its
282 length. The value is returned in the SV* argument */
284 If you know the name of a hash variable, you can get a pointer to its HV
285 by using the following:
287 HV* perl_get_hv("varname", FALSE);
289 This returns NULL if the variable does not exist.
291 The hash algorithm, for those who are interested, is:
297 hash = hash * 33 + *s++;
301 References are a special type of scalar that point to other data types
302 (including references).
304 To create a reference, use the following command:
306 SV* newRV((SV*) thing);
308 The C<thing> argument can be any of an C<SV*>, C<AV*>, or C<HV*>. Once
309 you have a reference, you can use the following macro to dereference the
314 then call the appropriate routines, casting the returned C<SV*> to either an
315 C<AV*> or C<HV*>, if required.
317 To determine if an SV is a reference, you can use the following macro:
321 To actually discover what the reference refers to, you must use the following
322 macro and then check the value returned.
326 The most useful types that will be returned are:
334 SVt_PVMG Blessed Scalar
336 =head2 Blessed References and Class Objects
338 References are also used to support object-oriented programming. In the
339 OO lexicon, an object is simply a reference that has been blessed into a
340 package (or class). Once blessed, the programmer may now use the reference
341 to access the various methods in the class.
343 A reference can be blessed into a package with the following function:
345 SV* sv_bless(SV* sv, HV* stash);
347 The C<sv> argument must be a reference. The C<stash> argument specifies
348 which class the reference will belong to. See the L<"Stashes">
349 for information on converting class names into stashes.
351 /* Still under construction */
353 Upgrades rv to reference if not already one. Creates new SV for rv to
355 If classname is non-null, the SV is blessed into the specified class.
358 SV* newSVrv(SV* rv, char* classname);
360 Copies integer or double into an SV whose reference is rv. SV is blessed
361 if classname is non-null.
363 SV* sv_setref_iv(SV* rv, char* classname, IV iv);
364 SV* sv_setref_nv(SV* rv, char* classname, NV iv);
366 Copies pointer (I<not a string!>) into an SV whose reference is rv.
367 SV is blessed if classname is non-null.
369 SV* sv_setref_pv(SV* rv, char* classname, PV iv);
371 Copies string into an SV whose reference is rv.
372 Set length to 0 to let Perl calculate the string length.
373 SV is blessed if classname is non-null.
375 SV* sv_setref_pvn(SV* rv, char* classname, PV iv, int length);
377 int sv_isa(SV* sv, char* name);
378 int sv_isobject(SV* sv);
380 =head1 Creating New Variables
382 To create a new Perl variable, which can be accessed from your Perl script,
383 use the following routines, depending on the variable type.
385 SV* perl_get_sv("varname", TRUE);
386 AV* perl_get_av("varname", TRUE);
387 HV* perl_get_hv("varname", TRUE);
389 Notice the use of TRUE as the second parameter. The new variable can now
390 be set, using the routines appropriate to the data type.
392 There are additional bits that may be OR'ed with the TRUE argument to enable
393 certain extra features. Those bits are:
395 0x02 Marks the variable as multiply defined, thus preventing the
396 "Identifier <varname> used only once: possible typo" warning.
397 0x04 Issues a "Had to create <varname> unexpectedly" warning if
398 the variable didn't actually exist. This is useful if
399 you expected the variable to already exist and want to propagate
400 this warning back to the user.
402 If the C<varname> argument does not contain a package specifier, it is
403 created in the current package.
405 =head1 XSUBs and the Argument Stack
407 The XSUB mechanism is a simple way for Perl programs to access C subroutines.
408 An XSUB routine will have a stack that contains the arguments from the Perl
409 program, and a way to map from the Perl data structures to a C equivalent.
411 The stack arguments are accessible through the C<ST(n)> macro, which returns
412 the C<n>'th stack argument. Argument 0 is the first argument passed in the
413 Perl subroutine call. These arguments are C<SV*>, and can be used anywhere
416 Most of the time, output from the C routine can be handled through use of
417 the RETVAL and OUTPUT directives. However, there are some cases where the
418 argument stack is not already long enough to handle all the return values.
419 An example is the POSIX tzname() call, which takes no arguments, but returns
420 two, the local timezone's standard and summer time abbreviations.
422 To handle this situation, the PPCODE directive is used and the stack is
423 extended using the macro:
427 where C<sp> is the stack pointer, and C<num> is the number of elements the
428 stack should be extended by.
430 Now that there is room on the stack, values can be pushed on it using the
431 macros to push IVs, doubles, strings, and SV pointers respectively:
438 And now the Perl program calling C<tzname>, the two values will be assigned
441 ($standard_abbrev, $summer_abbrev) = POSIX::tzname;
443 An alternate (and possibly simpler) method to pushing values on the stack is
451 These macros automatically adjust the stack for you, if needed.
453 For more information, consult L<perlxs>.
457 In Perl, values are normally "immortal" -- that is, they are not freed unless
458 explicitly done so (via the Perl C<undef> call or other routines in Perl
461 Add cruft about reference counts.
462 int SvREFCNT(SV* sv);
463 void SvREFCNT_inc(SV* sv);
464 void SvREFCNT_dec(SV* sv);
466 In the above example with C<tzname>, we needed to create two new SVs to push
467 onto the argument stack, that being the two strings. However, we don't want
468 these new SVs to stick around forever because they will eventually be
469 copied into the SVs that hold the two scalar variables.
471 An SV (or AV or HV) that is "mortal" acts in all ways as a normal "immortal"
472 SV, AV, or HV, but is only valid in the "current context". When the Perl
473 interpreter leaves the current context, the mortal SV, AV, or HV is
474 automatically freed. Generally the "current context" means a single
477 To create a mortal variable, use the functions:
481 SV* sv_mortalcopy(SV*)
483 The first call creates a mortal SV, the second converts an existing SV to
484 a mortal SV, the third creates a mortal copy of an existing SV.
486 The mortal routines are not just for SVs -- AVs and HVs can be made mortal
487 by passing their address (and casting them to C<SV*>) to the C<sv_2mortal> or
488 C<sv_mortalcopy> routines.
491 Beware that the sv_2mortal() call is eventually equivalent to
492 svREFCNT_dec(). A value can happily be mortal in two different contexts,
493 and it will be svREFCNT_dec()ed twice, once on exit from these
494 contexts. It can also be mortal twice in the same context. This means
495 that you should be very careful to make a value mortal exactly as many
496 times as it is needed. The value that go to the Perl stack I<should>
499 You should be careful about creating mortal variables. It is possible for
500 strange things to happen should you make the same value mortal within
505 A stash is a hash table (associative array) that contains all of the
506 different objects that are contained within a package. Each key of the
507 stash is a symbol name (shared by all the different types of objects
508 that have the same name), and each value in the hash table is called a
509 GV (for Glob Value). This GV in turn contains references to the various
510 objects of that name, including (but not limited to) the following:
520 Perl stores various stashes in a separate GV structure (for global
521 variable) but represents them with an HV structure. The keys in this
522 larger GV are the various package names; the values are the C<GV*>s
523 which are stashes. It may help to think of a stash purely as an HV,
524 and that the term "GV" means the global variable hash.
526 To get the stash pointer for a particular package, use the function:
528 HV* gv_stashpv(char* name, I32 create)
529 HV* gv_stashsv(SV*, I32 create)
531 The first function takes a literal string, the second uses the string stored
532 in the SV. Remember that a stash is just a hash table, so you get back an
533 C<HV*>. The C<create> flag will create a new package if it is set.
535 The name that C<gv_stash*v> wants is the name of the package whose symbol table
536 you want. The default package is called C<main>. If you have multiply nested
537 packages, pass their names to C<gv_stash*v>, separated by C<::> as in the Perl
540 Alternately, if you have an SV that is a blessed reference, you can find
541 out the stash pointer by using:
543 HV* SvSTASH(SvRV(SV*));
545 then use the following to get the package name itself:
547 char* HvNAME(HV* stash);
549 If you need to return a blessed value to your Perl script, you can use the
552 SV* sv_bless(SV*, HV* stash)
554 where the first argument, an C<SV*>, must be a reference, and the second
555 argument is a stash. The returned C<SV*> can now be used in the same way
558 For more information on references and blessings, consult L<perlref>.
562 [This section still under construction. Ignore everything here. Post no
563 bills. Everything not permitted is forbidden.]
565 Any SV may be magical, that is, it has special features that a normal
566 SV does not have. These features are stored in the SV structure in a
567 linked list of C<struct magic>s, typedef'ed to C<MAGIC>.
580 Note this is current as of patchlevel 0, and could change at any time.
582 =head2 Assigning Magic
584 Perl adds magic to an SV using the sv_magic function:
586 void sv_magic(SV* sv, SV* obj, int how, char* name, I32 namlen);
588 The C<sv> argument is a pointer to the SV that is to acquire a new magical
591 If C<sv> is not already magical, Perl uses the C<SvUPGRADE> macro to
592 set the C<SVt_PVMG> flag for the C<sv>. Perl then continues by adding
593 it to the beginning of the linked list of magical features. Any prior
594 entry of the same type of magic is deleted. Note that this can be
595 overridden, and multiple instances of the same type of magic can be
596 associated with an SV.
598 The C<name> and C<namlem> arguments are used to associate a string with
599 the magic, typically the name of a variable. C<namlem> is stored in the
600 C<mg_len> field and if C<name> is non-null and C<namlem> E<gt>= 0 a malloc'd
601 copy of the name is stored in C<mg_ptr> field.
603 The sv_magic function uses C<how> to determine which, if any, predefined
604 "Magic Virtual Table" should be assigned to the C<mg_virtual> field.
605 See the "Magic Virtual Table" section below. The C<how> argument is also
606 stored in the C<mg_type> field.
608 The C<obj> argument is stored in the C<mg_obj> field of the C<MAGIC>
609 structure. If it is not the same as the C<sv> argument, the reference
610 count of the C<obj> object is incremented. If it is the same, or if
611 the C<how> argument is "#", or if it is a null pointer, then C<obj> is
612 merely stored, without the reference count being incremented.
614 There is also a function to add magic to an C<HV>:
616 void hv_magic(HV *hv, GV *gv, int how);
618 This simply calls C<sv_magic> and coerces the C<gv> argument into an C<SV>.
620 To remove the magic from an SV, call the function sv_unmagic:
622 void sv_unmagic(SV *sv, int type);
624 The C<type> argument should be equal to the C<how> value when the C<SV>
625 was initially made magical.
627 =head2 Magic Virtual Tables
629 The C<mg_virtual> field in the C<MAGIC> structure is a pointer to a
630 C<MGVTBL>, which is a structure of function pointers and stands for
631 "Magic Virtual Table" to handle the various operations that might be
632 applied to that variable.
634 The C<MGVTBL> has five pointers to the following routine types:
636 int (*svt_get)(SV* sv, MAGIC* mg);
637 int (*svt_set)(SV* sv, MAGIC* mg);
638 U32 (*svt_len)(SV* sv, MAGIC* mg);
639 int (*svt_clear)(SV* sv, MAGIC* mg);
640 int (*svt_free)(SV* sv, MAGIC* mg);
642 This MGVTBL structure is set at compile-time in C<perl.h> and there are
643 currently 19 types (or 21 with overloading turned on). These different
644 structures contain pointers to various routines that perform additional
645 actions depending on which function is being called.
647 Function pointer Action taken
648 ---------------- ------------
649 svt_get Do something after the value of the SV is retrieved.
650 svt_set Do something after the SV is assigned a value.
651 svt_len Report on the SV's length.
652 svt_clear Clear something the SV represents.
653 svt_free Free any extra storage associated with the SV.
655 For instance, the MGVTBL structure called C<vtbl_sv> (which corresponds
656 to an C<mg_type> of '\0') contains:
658 { magic_get, magic_set, magic_len, 0, 0 }
660 Thus, when an SV is determined to be magical and of type '\0', if a get
661 operation is being performed, the routine C<magic_get> is called. All
662 the various routines for the various magical types begin with C<magic_>.
664 The current kinds of Magic Virtual Tables are:
666 mg_type MGVTBL Type of magicalness
667 ------- ------ -------------------
669 A vtbl_amagic Operator Overloading
670 a vtbl_amagicelem Operator Overloading
671 c 0 Used in Operator Overloading
672 B vtbl_bm Boyer-Moore???
674 e vtbl_envelem %ENV hash element
675 g vtbl_mglob Regexp /g flag???
676 I vtbl_isa @ISA array
677 i vtbl_isaelem @ISA array element
678 L 0 (but sets RMAGICAL) Perl Module/Debugger???
679 l vtbl_dbline Debugger?
680 P vtbl_pack Tied Array or Hash
681 p vtbl_packelem Tied Array or Hash element
682 q vtbl_packelem Tied Scalar or Handle
683 S vtbl_sig Signal Hash
684 s vtbl_sigelem Signal Hash element
685 t vtbl_taint Taintedness
688 x vtbl_substr Substring???
690 # vtbl_arylen Array Length
691 . vtbl_pos $. scalar variable
692 ~ Reserved for extensions, but multiple extensions may clash
694 When an upper-case and lower-case letter both exist in the table, then the
695 upper-case letter is used to represent some kind of composite type (a list
696 or a hash), and the lower-case letter is used to represent an element of
701 MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */
703 This routine returns a pointer to the C<MAGIC> structure stored in the SV.
704 If the SV does not have that magical feature, C<NULL> is returned. Also,
705 if the SV is not of type SVt_PVMG, Perl may core-dump.
707 int mg_copy(SV* sv, SV* nsv, char* key, STRLEN klen);
709 This routine checks to see what types of magic C<sv> has. If the mg_type
710 field is an upper-case letter, then the mg_obj is copied to C<nsv>, but
711 the mg_type field is changed to be the lower-case letter.
713 =head1 Double-Typed SVs
715 Scalar variables normally contain only one type of value, an integer,
716 double, pointer, or reference. Perl will automatically convert the
717 actual scalar data from the stored type into the requested type.
719 Some scalar variables contain more than one type of scalar data. For
720 example, the variable C<$!> contains either the numeric value of C<errno>
721 or its string equivalent from either C<strerror> or C<sys_errlist[]>.
723 To force multiple data values into an SV, you must do two things: use the
724 C<sv_set*v> routines to add the additional scalar type, then set a flag
725 so that Perl will believe it contains more than one type of data. The
726 four macros to set the flags are:
733 The particular macro you must use depends on which C<sv_set*v> routine
734 you called first. This is because every C<sv_set*v> routine turns on
735 only the bit for the particular type of data being set, and turns off
738 For example, to create a new Perl variable called "dberror" that contains
739 both the numeric and descriptive string error values, you could use the
743 extern char *dberror_list;
745 SV* sv = perl_get_sv("dberror", TRUE);
746 sv_setiv(sv, (IV) dberror);
747 sv_setpv(sv, dberror_list[dberror]);
750 If the order of C<sv_setiv> and C<sv_setpv> had been reversed, then the
751 macro C<SvPOK_on> would need to be called instead of C<SvIOK_on>.
753 =head1 Calling Perl Routines from within C Programs
755 There are four routines that can be used to call a Perl subroutine from
756 within a C program. These four are:
758 I32 perl_call_sv(SV*, I32);
759 I32 perl_call_pv(char*, I32);
760 I32 perl_call_method(char*, I32);
761 I32 perl_call_argv(char*, I32, register char**);
763 The routine most often used is C<perl_call_sv>. The C<SV*> argument
764 contains either the name of the Perl subroutine to be called, or a
765 reference to the subroutine. The second argument consists of flags
766 that control the context in which the subroutine is called, whether
767 or not the subroutine is being passed arguments, how errors should be
768 trapped, and how to treat return values.
770 All four routines return the number of arguments that the subroutine returned
773 When using any of these routines (except C<perl_call_argv>), the programmer
774 must manipulate the Perl stack. These include the following macros and
788 For more information, consult L<perlcall>.
790 =head1 Memory Allocation
792 It is strongly suggested that you use the version of malloc that is distributed
793 with Perl. It keeps pools of various sizes of unallocated memory in order to
794 more quickly satisfy allocation requests.
795 However, on some platforms, it may cause spurious malloc or free errors.
797 New(x, pointer, number, type);
798 Newc(x, pointer, number, type, cast);
799 Newz(x, pointer, number, type);
801 These three macros are used to initially allocate memory. The first argument
802 C<x> was a "magic cookie" that was used to keep track of who called the macro,
803 to help when debugging memory problems. However, the current code makes no
804 use of this feature (Larry has switched to using a run-time memory checker),
805 so this argument can be any number.
807 The second argument C<pointer> will point to the newly allocated memory.
808 The third and fourth arguments C<number> and C<type> specify how many of
809 the specified type of data structure should be allocated. The argument
810 C<type> is passed to C<sizeof>. The final argument to C<Newc>, C<cast>,
811 should be used if the C<pointer> argument is different from the C<type>
814 Unlike the C<New> and C<Newc> macros, the C<Newz> macro calls C<memzero>
815 to zero out all the newly allocated memory.
817 Renew(pointer, number, type);
818 Renewc(pointer, number, type, cast);
821 These three macros are used to change a memory buffer size or to free a
822 piece of memory no longer needed. The arguments to C<Renew> and C<Renewc>
823 match those of C<New> and C<Newc> with the exception of not needing the
824 "magic cookie" argument.
826 Move(source, dest, number, type);
827 Copy(source, dest, number, type);
828 Zero(dest, number, type);
830 These three macros are used to move, copy, or zero out previously allocated
831 memory. The C<source> and C<dest> arguments point to the source and
832 destination starting points. Perl will move, copy, or zero out C<number>
833 instances of the size of the C<type> data structure (using the C<sizeof>
838 This is a listing of functions, macros, flags, and variables that may be
839 useful to extension writers or that may be found while reading other
850 Clears an array, making it empty.
852 void av_clear _((AV* ar));
856 Pre-extend an array. The C<key> is the index to which the array should be
859 void av_extend _((AV* ar, I32 key));
863 Returns the SV at the specified index in the array. The C<key> is the
864 index. If C<lval> is set then the fetch will be part of a store. Check
865 that the return value is non-null before dereferencing it to a C<SV*>.
867 SV** av_fetch _((AV* ar, I32 key, I32 lval));
871 Returns the highest index in the array. Returns -1 if the array is empty.
873 I32 av_len _((AV* ar));
877 Creates a new AV and populates it with a list of SVs. The SVs are copied
878 into the array, so they may be freed after the call to av_make. The new AV
879 will have a refcount of 1.
881 AV* av_make _((I32 size, SV** svp));
885 Pops an SV off the end of the array. Returns C<&sv_undef> if the array is
888 SV* av_pop _((AV* ar));
892 Pushes an SV onto the end of the array. The array will grow automatically
893 to accommodate the addition.
895 void av_push _((AV* ar, SV* val));
899 Shifts an SV off the beginning of the array.
901 SV* av_shift _((AV* ar));
905 Stores an SV in an array. The array index is specified as C<key>. The
906 return value will be null if the operation failed, otherwise it can be
907 dereferenced to get the original C<SV*>.
909 SV** av_store _((AV* ar, I32 key, SV* val));
915 void av_undef _((AV* ar));
919 Unshift an SV onto the beginning of the array. The array will grow
920 automatically to accommodate the addition.
922 void av_unshift _((AV* ar, I32 num));
926 Variable which is setup by C<xsubpp> to indicate the class name for a C++ XS
927 constructor. This is always a C<char*>. See C<THIS> and
928 L<perlxs/"Using XS With C++">.
932 The XSUB-writer's interface to the C C<memcpy> function. The C<s> is the
933 source, C<d> is the destination, C<n> is the number of items, and C<t> is
936 (void) Copy( s, d, n, t );
940 This is the XSUB-writer's interface to Perl's C<die> function. Use this
941 function the same way you use the C C<printf> function. See C<warn>.
945 Returns the stash of the CV.
947 HV * CvSTASH( SV* sv )
951 When Perl is run in debugging mode, with the B<-d> switch, this SV is a
952 boolean which indicates whether subs are being single-stepped.
953 Single-stepping is automatically turned on after every step. This is the C
954 variable which corresponds to Perl's $DB::single variable. See C<DBsub>.
958 When Perl is run in debugging mode, with the B<-d> switch, this GV contains
959 the SV which holds the name of the sub being debugged. This is the C
960 variable which corresponds to Perl's $DB::sub variable. See C<DBsingle>.
961 The sub name can be found by
963 SvPV( GvSV( DBsub ), na )
967 Trace variable used when Perl is run in debugging mode, with the B<-d>
968 switch. This is the C variable which corresponds to Perl's $DB::trace
969 variable. See C<DBsingle>.
973 Declare a stack marker variable, C<mark>, for the XSUB. See C<MARK> and
978 Saves the original stack mark for the XSUB. See C<ORIGMARK>.
982 The C variable which corresponds to Perl's $^W warning variable.
986 Declares a stack pointer variable, C<sp>, for the XSUB. See C<SP>.
990 Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is
991 usually handled automatically by C<xsubpp>. Declares the C<items> variable
992 to indicate the number of items on the stack.
996 Sets up the C<ix> variable for an XSUB which has aliases. This is usually
997 handled automatically by C<xsubpp>.
1001 Sets up the C<ix> variable for an XSUB which has aliases. This is usually
1002 handled automatically by C<xsubpp>.
1006 Opening bracket on a callback. See C<LEAVE> and L<perlcall>.
1012 Used to extend the argument stack for an XSUB's return values.
1014 EXTEND( sp, int x );
1018 Closing bracket for temporaries on a callback. See C<SAVETMPS> and
1025 Used to indicate array context. See C<GIMME> and L<perlcall>.
1029 Indicates that arguments returned from a callback should be discarded. See
1034 Used to force a Perl C<eval> wrapper around a callback. See L<perlcall>.
1038 The XSUB-writer's equivalent to Perl's C<wantarray>. Returns C<G_SCALAR> or
1039 C<G_ARRAY> for scalar or array context.
1043 Indicates that no arguments are being sent to a callback. See L<perlcall>.
1047 Used to indicate scalar context. See C<GIMME> and L<perlcall>.
1051 Returns a pointer to the stash for a specified package. If C<create> is set
1052 then the package will be created if it does not already exist. If C<create>
1053 is not set and the package does not exist then NULL is returned.
1055 HV* gv_stashpv _((char* name, I32 create));
1059 Returns a pointer to the stash for a specified package. See C<gv_stashpv>.
1061 HV* gv_stashsv _((SV* sv, I32 create));
1065 Return the SV from the GV.
1069 Releases a hash entry from an iterator. See C<hv_iternext>.
1073 Clears a hash, making it empty.
1075 void hv_clear _((HV* tb));
1079 Deletes a key/value pair in the hash. The value SV is removed from the hash
1080 and returned to the caller. The C<klen> is the length of the key. The
1081 C<flags> value will normally be zero; if set to G_DISCARD then null will be
1084 SV* hv_delete _((HV* tb, char* key, U32 klen, I32 flags));
1088 Returns a boolean indicating whether the specified hash key exists. The
1089 C<klen> is the length of the key.
1091 bool hv_exists _((HV* tb, char* key, U32 klen));
1095 Returns the SV which corresponds to the specified key in the hash. The
1096 C<klen> is the length of the key. If C<lval> is set then the fetch will be
1097 part of a store. Check that the return value is non-null before
1098 dereferencing it to a C<SV*>.
1100 SV** hv_fetch _((HV* tb, char* key, U32 klen, I32 lval));
1104 Prepares a starting point to traverse a hash table.
1106 I32 hv_iterinit _((HV* tb));
1110 Returns the key from the current position of the hash iterator. See
1113 char* hv_iterkey _((HE* entry, I32* retlen));
1117 Returns entries from a hash iterator. See C<hv_iterinit>.
1119 HE* hv_iternext _((HV* tb));
1123 Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one
1126 SV * hv_iternextsv _((HV* hv, char** key, I32* retlen));
1130 Returns the value from the current position of the hash iterator. See
1133 SV* hv_iterval _((HV* tb, HE* entry));
1137 Adds magic to a hash. See C<sv_magic>.
1139 void hv_magic _((HV* hv, GV* gv, int how));
1143 Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>.
1145 char *HvNAME (HV* stash)
1149 Stores an SV in a hash. The hash key is specified as C<key> and C<klen> is
1150 the length of the key. The C<hash> parameter is the pre-computed hash
1151 value; if it is zero then Perl will compute it. The return value will be
1152 null if the operation failed, otherwise it can be dereferenced to get the
1155 SV** hv_store _((HV* tb, char* key, U32 klen, SV* val, U32 hash));
1161 void hv_undef _((HV* tb));
1165 Returns a boolean indicating whether the C C<char> is an ascii alphanumeric
1168 int isALNUM (char c)
1172 Returns a boolean indicating whether the C C<char> is an ascii alphabetic
1175 int isALPHA (char c)
1179 Returns a boolean indicating whether the C C<char> is an ascii digit.
1181 int isDIGIT (char c)
1185 Returns a boolean indicating whether the C C<char> is a lowercase character.
1187 int isLOWER (char c)
1191 Returns a boolean indicating whether the C C<char> is whitespace.
1193 int isSPACE (char c)
1197 Returns a boolean indicating whether the C C<char> is an uppercase character.
1199 int isUPPER (char c)
1203 Variable which is setup by C<xsubpp> to indicate the number of items on the
1204 stack. See L<perlxs/"Variable-length Parameter Lists">.
1208 Variable which is setup by C<xsubpp> to indicate which of an XSUB's aliases
1209 was used to invoke it. See L<perlxs/"The ALIAS: Keyword">.
1213 Closing bracket on a callback. See C<ENTER> and L<perlcall>.
1219 Stack marker variable for the XSUB. See C<dMARK>.
1223 Clear something magical that the SV represents. See C<sv_magic>.
1225 int mg_clear _((SV* sv));
1229 Copies the magic from one SV to another. See C<sv_magic>.
1231 int mg_copy _((SV *, SV *, char *, STRLEN));
1235 Finds the magic pointer for type matching the SV. See C<sv_magic>.
1237 MAGIC* mg_find _((SV* sv, int type));
1241 Free any magic storage used by the SV. See C<sv_magic>.
1243 int mg_free _((SV* sv));
1247 Do magic after a value is retrieved from the SV. See C<sv_magic>.
1249 int mg_get _((SV* sv));
1253 Report on the SV's length. See C<sv_magic>.
1255 U32 mg_len _((SV* sv));
1259 Turns on the magical status of an SV. See C<sv_magic>.
1261 void mg_magical _((SV* sv));
1265 Do magic after a value is assigned to the SV. See C<sv_magic>.
1267 int mg_set _((SV* sv));
1271 The XSUB-writer's interface to the C C<memmove> function. The C<s> is the
1272 source, C<d> is the destination, C<n> is the number of items, and C<t> is
1275 (void) Move( s, d, n, t );
1279 A variable which may be used with C<SvPV> to tell Perl to calculate the
1284 The XSUB-writer's interface to the C C<malloc> function.
1286 void * New( x, void *ptr, int size, type )
1290 The XSUB-writer's interface to the C C<malloc> function, with cast.
1292 void * Newc( x, void *ptr, int size, type, cast )
1296 The XSUB-writer's interface to the C C<malloc> function. The allocated
1297 memory is zeroed with C<memzero>.
1299 void * Newz( x, void *ptr, int size, type )
1303 Creates a new AV. The refcount is set to 1.
1305 AV* newAV _((void));
1309 Creates a new HV. The refcount is set to 1.
1311 HV* newHV _((void));
1315 Creates an RV wrapper for an SV. The refcount for the original SV is
1318 SV* newRV _((SV* ref));
1322 Creates a new SV. The C<len> parameter indicates the number of bytes of
1323 pre-allocated string space the SV should have. The refcount for the new SV
1326 SV* newSV _((STRLEN len));
1330 Creates a new SV and copies an integer into it. The refcount for the SV is
1333 SV* newSViv _((IV i));
1337 Creates a new SV and copies a double into it. The refcount for the SV is
1340 SV* newSVnv _((NV i));
1344 Creates a new SV and copies a string into it. The refcount for the SV is
1345 set to 1. If C<len> is zero then Perl will compute the length.
1347 SV* newSVpv _((char* s, STRLEN len));
1351 Creates a new SV for the RV, C<rv>, to point to. If C<rv> is not an RV then
1352 it will be upgraded to one. If C<classname> is non-null then the new SV will
1353 be blessed in the specified package. The new SV is returned and its
1356 SV* newSVrv _((SV* rv, char* classname));
1360 Creates a new SV which is an exact duplicate of the original SV.
1362 SV* newSVsv _((SV* old));
1366 Used by C<xsubpp> to hook up XSUBs as Perl subs.
1370 Used by C<xsubpp> to hook up XSUBs as Perl subs. Adds Perl prototypes to
1379 Null character pointer.
1395 The original stack mark for the XSUB. See C<dORIGMARK>.
1399 Allocates a new Perl interpreter. See L<perlembed>.
1401 =item perl_call_argv
1403 Performs a callback to the specified Perl sub. See L<perlcall>.
1405 I32 perl_call_argv _((char* subname, I32 flags, char** argv));
1407 =item perl_call_method
1409 Performs a callback to the specified Perl method. The blessed object must
1410 be on the stack. See L<perlcall>.
1412 I32 perl_call_method _((char* methname, I32 flags));
1416 Performs a callback to the specified Perl sub. See L<perlcall>.
1418 I32 perl_call_pv _((char* subname, I32 flags));
1422 Performs a callback to the Perl sub whose name is in the SV. See
1425 I32 perl_call_sv _((SV* sv, I32 flags));
1427 =item perl_construct
1429 Initializes a new Perl interpreter. See L<perlembed>.
1433 Shuts down a Perl interpreter. See L<perlembed>.
1437 Tells Perl to C<eval> the string in the SV.
1439 I32 perl_eval_sv _((SV* sv, I32 flags));
1443 Releases a Perl interpreter. See L<perlembed>.
1447 Returns the AV of the specified Perl array. If C<create> is set and the
1448 Perl variable does not exist then it will be created. If C<create> is not
1449 set and the variable does not exist then null is returned.
1451 AV* perl_get_av _((char* name, I32 create));
1455 Returns the CV of the specified Perl sub. If C<create> is set and the Perl
1456 variable does not exist then it will be created. If C<create> is not
1457 set and the variable does not exist then null is returned.
1459 CV* perl_get_cv _((char* name, I32 create));
1463 Returns the HV of the specified Perl hash. If C<create> is set and the Perl
1464 variable does not exist then it will be created. If C<create> is not
1465 set and the variable does not exist then null is returned.
1467 HV* perl_get_hv _((char* name, I32 create));
1471 Returns the SV of the specified Perl scalar. If C<create> is set and the
1472 Perl variable does not exist then it will be created. If C<create> is not
1473 set and the variable does not exist then null is returned.
1475 SV* perl_get_sv _((char* name, I32 create));
1479 Tells a Perl interpreter to parse a Perl script. See L<perlembed>.
1481 =item perl_require_pv
1483 Tells Perl to C<require> a module.
1485 void perl_require_pv _((char* pv));
1489 Tells a Perl interpreter to run. See L<perlembed>.
1493 Pops an integer off the stack.
1499 Pops a long off the stack.
1505 Pops a string off the stack.
1511 Pops a double off the stack.
1517 Pops an SV off the stack.
1523 Opening bracket for arguments on a callback. See C<PUTBACK> and L<perlcall>.
1529 Push an integer onto the stack. The stack must have room for this element.
1536 Push a double onto the stack. The stack must have room for this element.
1543 Push a string onto the stack. The stack must have room for this element.
1544 The C<len> indicates the length of the string. See C<XPUSHp>.
1546 PUSHp(char *c, int len )
1550 Push an SV onto the stack. The stack must have room for this element. See
1557 Closing bracket for XSUB arguments. This is usually handled by C<xsubpp>.
1558 See C<PUSHMARK> and L<perlcall> for other uses.
1564 The XSUB-writer's interface to the C C<realloc> function.
1566 void * Renew( void *ptr, int size, type )
1570 The XSUB-writer's interface to the C C<realloc> function, with cast.
1572 void * Renewc( void *ptr, int size, type, cast )
1576 Variable which is setup by C<xsubpp> to hold the return value for an XSUB.
1577 This is always the proper type for the XSUB.
1578 See L<perlxs/"The RETVAL Variable">.
1582 The XSUB-writer's interface to the C C<free> function.
1586 The XSUB-writer's interface to the C C<malloc> function.
1590 The XSUB-writer's interface to the C C<realloc> function.
1594 Copy a string to a safe spot. This does not use an SV.
1596 char* savepv _((char* sv));
1600 Copy a string to a safe spot. The C<len> indicates number of bytes to
1601 copy. This does not use an SV.
1603 char* savepvn _((char* sv, I32 len));
1607 Opening bracket for temporaries on a callback. See C<FREETMPS> and
1614 Stack pointer. This is usually handled by C<xsubpp>. See C<dSP> and
1619 Refetch the stack pointer. Used after a callback. See L<perlcall>.
1625 Used to access elements on the XSUB's stack.
1631 Test two strings to see if they are equal. Returns true or false.
1633 int strEQ( char *s1, char *s2 )
1637 Test two strings to see if the first, C<s1>, is greater than or equal to the
1638 second, C<s2>. Returns true or false.
1640 int strGE( char *s1, char *s2 )
1644 Test two strings to see if the first, C<s1>, is greater than the second,
1645 C<s2>. Returns true or false.
1647 int strGT( char *s1, char *s2 )
1651 Test two strings to see if the first, C<s1>, is less than or equal to the
1652 second, C<s2>. Returns true or false.
1654 int strLE( char *s1, char *s2 )
1658 Test two strings to see if the first, C<s1>, is less than the second,
1659 C<s2>. Returns true or false.
1661 int strLT( char *s1, char *s2 )
1665 Test two strings to see if they are different. Returns true or false.
1667 int strNE( char *s1, char *s2 )
1671 Test two strings to see if they are equal. The C<len> parameter indicates
1672 the number of bytes to compare. Returns true or false.
1674 int strnEQ( char *s1, char *s2 )
1678 Test two strings to see if they are different. The C<len> parameter
1679 indicates the number of bytes to compare. Returns true or false.
1681 int strnNE( char *s1, char *s2, int len )
1685 Marks an SV as mortal. The SV will be destroyed when the current context
1688 SV* sv_2mortal _((SV* sv));
1692 Blesses an SV into a specified package. The SV must be an RV. The package
1693 must be designated by its stash (see C<gv_stashpv()>). The refcount of the
1696 SV* sv_bless _((SV* sv, HV* stash));
1700 Concatenates the string onto the end of the string which is in the SV.
1702 void sv_catpv _((SV* sv, char* ptr));
1706 Concatenates the string onto the end of the string which is in the SV. The
1707 C<len> indicates number of bytes to copy.
1709 void sv_catpvn _((SV* sv, char* ptr, STRLEN len));
1713 Concatenates the string from SV C<ssv> onto the end of the string in SV
1716 void sv_catsv _((SV* dsv, SV* ssv));
1720 Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the
1721 string in C<sv1> is less than, equal to, or greater than the string in
1724 I32 sv_cmp _((SV* sv1, SV* sv2));
1728 Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the
1729 string in C<sv1> is less than, equal to, or greater than the string in
1732 I32 sv_cmp _((SV* sv1, SV* sv2));
1736 Returns the length of the string which is in the SV. See C<SvLEN>.
1742 Set the length of the string which is in the SV. See C<SvCUR>.
1744 SvCUR_set (SV* sv, int val )
1748 Autodecrement of the value in the SV.
1750 void sv_dec _((SV* sv));
1754 Autodecrement of the value in the SV.
1756 void sv_dec _((SV* sv));
1760 Returns a pointer to the last character in the string which is in the SV.
1761 See C<SvCUR>. Access the character as
1767 Returns a boolean indicating whether the strings in the two SVs are
1770 I32 sv_eq _((SV* sv1, SV* sv2));
1774 Expands the character buffer in the SV. Calls C<sv_grow> to perform the
1775 expansion if necessary. Returns a pointer to the character buffer.
1777 char * SvGROW( SV* sv, int len )
1781 Expands the character buffer in the SV. This will use C<sv_unref> and will
1782 upgrade the SV to C<SVt_PV>. Returns a pointer to the character buffer.
1787 Autoincrement of the value in the SV.
1789 void sv_inc _((SV* sv));
1793 Returns a boolean indicating whether the SV contains an integer.
1799 Unsets the IV status of an SV.
1805 Tells an SV that it is an integer.
1811 Tells an SV that it is an integer and disables all other OK bits.
1817 Tells an SV that it is an integer and disables all other OK bits.
1823 Returns a boolean indicating whether the SV contains an integer. Checks the
1824 B<private> setting. Use C<SvIOK>.
1830 Returns a boolean indicating whether the SV is blessed into the specified
1831 class. This does not know how to check for subtype, so it doesn't work in
1832 an inheritance relationship.
1834 int sv_isa _((SV* sv, char* name));
1838 Returns the integer which is in the SV.
1844 Returns a boolean indicating whether the SV is an RV pointing to a blessed
1845 object. If the SV is not an RV, or if the object is not blessed, then this
1848 int sv_isobject _((SV* sv));
1852 Returns the integer which is stored in the SV.
1858 Returns the size of the string buffer in the SV. See C<SvCUR>.
1864 Returns the length of the string in the SV. Use C<SvCUR>.
1866 STRLEN sv_len _((SV* sv));
1870 Returns the length of the string in the SV. Use C<SvCUR>.
1872 STRLEN sv_len _((SV* sv));
1876 Adds magic to an SV.
1878 void sv_magic _((SV* sv, SV* obj, int how, char* name, I32 namlen));
1882 Creates a new SV which is a copy of the original SV. The new SV is marked
1885 SV* sv_mortalcopy _((SV* oldsv));
1889 Returns a boolean indicating whether the value is an SV.
1895 Creates a new SV which is mortal. The refcount of the SV is set to 1.
1897 SV* sv_newmortal _((void));
1901 This is the C<false> SV. See C<sv_yes>. Always refer to this as C<&sv_no>.
1905 Returns a boolean indicating whether the SV contains a number, integer or
1912 Unsets the NV/IV status of an SV.
1918 Returns a boolean indicating whether the SV contains a number, integer or
1919 double. Checks the B<private> setting. Use C<SvNIOK>.
1921 int SvNIOKp (SV* SV)
1925 Returns a boolean indicating whether the SV contains a double.
1931 Unsets the NV status of an SV.
1937 Tells an SV that it is a double.
1943 Tells an SV that it is a double and disables all other OK bits.
1949 Tells an SV that it is a double and disables all other OK bits.
1955 Returns a boolean indicating whether the SV contains a double. Checks the
1956 B<private> setting. Use C<SvNOK>.
1962 Returns the double which is stored in the SV.
1964 double SvNV (SV* sv);
1968 Returns the double which is stored in the SV.
1970 double SvNVX (SV* sv);
1974 Returns a boolean indicating whether the SV contains a character string.
1980 Unsets the PV status of an SV.
1986 Tells an SV that it is a string.
1992 Tells an SV that it is a string and disables all other OK bits.
1998 Tells an SV that it is a string and disables all other OK bits.
2004 Returns a boolean indicating whether the SV contains a character string.
2005 Checks the B<private> setting. Use C<SvPOK>.
2011 Returns a pointer to the string in the SV, or a stringified form of the SV
2012 if the SV does not contain a string. If C<len> is C<na> then Perl will
2013 handle the length on its own.
2015 char * SvPV (SV* sv, int len )
2019 Returns a pointer to the string in the SV. The SV must contain a string.
2021 char * SvPVX (SV* sv)
2025 Returns the value of the object's refcount.
2027 int SvREFCNT (SV* sv);
2031 Decrements the refcount of the given SV.
2033 void SvREFCNT_dec (SV* sv)
2037 Increments the refcount of the given SV.
2039 void SvREFCNT_inc (SV* sv)
2043 Tests if the SV is an RV.
2049 Unsets the RV status of an SV.
2055 Tells an SV that it is an RV.
2061 Dereferences an RV to return the SV.
2067 Copies an integer into the given SV.
2069 void sv_setiv _((SV* sv, IV num));
2073 Copies a double into the given SV.
2075 void sv_setnv _((SV* sv, double num));
2079 Copies a string into an SV. The string must be null-terminated.
2081 void sv_setpv _((SV* sv, char* ptr));
2085 Copies a string into an SV. The C<len> parameter indicates the number of
2088 void sv_setpvn _((SV* sv, char* ptr, STRLEN len));
2092 Copies an integer into a new SV, optionally blessing the SV. The C<rv>
2093 argument will be upgraded to an RV. That RV will be modified to point to
2094 the new SV. The C<classname> argument indicates the package for the
2095 blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV
2096 will be returned and will have a refcount of 1.
2098 SV* sv_setref_iv _((SV *rv, char *classname, IV iv));
2102 Copies a double into a new SV, optionally blessing the SV. The C<rv>
2103 argument will be upgraded to an RV. That RV will be modified to point to
2104 the new SV. The C<classname> argument indicates the package for the
2105 blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV
2106 will be returned and will have a refcount of 1.
2108 SV* sv_setref_nv _((SV *rv, char *classname, double nv));
2112 Copies a pointer into a new SV, optionally blessing the SV. The C<rv>
2113 argument will be upgraded to an RV. That RV will be modified to point to
2114 the new SV. If the C<pv> argument is NULL then C<sv_undef> will be placed
2115 into the SV. The C<classname> argument indicates the package for the
2116 blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV
2117 will be returned and will have a refcount of 1.
2119 SV* sv_setref_pv _((SV *rv, char *classname, void* pv));
2121 Do not use with integral Perl types such as HV, AV, SV, CV, because those
2122 objects will become corrupted by the pointer copy process.
2124 Note that C<sv_setref_pvn> copies the string while this copies the pointer.
2128 Copies a string into a new SV, optionally blessing the SV. The length of the
2129 string must be specified with C<n>. The C<rv> argument will be upgraded to
2130 an RV. That RV will be modified to point to the new SV. The C<classname>
2131 argument indicates the package for the blessing. Set C<classname> to
2132 C<Nullch> to avoid the blessing. The new SV will be returned and will have
2135 SV* sv_setref_pvn _((SV *rv, char *classname, char* pv, I32 n));
2137 Note that C<sv_setref_pv> copies the pointer while this copies the string.
2141 Copies the contents of the source SV C<ssv> into the destination SV C<dsv>.
2142 The source SV may be destroyed if it is mortal.
2144 void sv_setsv _((SV* dsv, SV* ssv));
2148 Returns the stash of the SV.
2150 HV * SvSTASH (SV* sv)
2154 Integer type flag for scalars. See C<svtype>.
2158 Pointer type flag for scalars. See C<svtype>.
2162 Type flag for arrays. See C<svtype>.
2166 Type flag for code refs. See C<svtype>.
2170 Type flag for hashes. See C<svtype>.
2174 Type flag for blessed scalars. See C<svtype>.
2178 Double type flag for scalars. See C<svtype>.
2182 Returns a boolean indicating whether Perl would evaluate the SV as true or
2183 false, defined or undefined.
2189 Returns the type of the SV. See C<svtype>.
2191 svtype SvTYPE (SV* sv)
2195 An enum of flags for Perl types. These are found in the file B<sv.h> in the
2196 C<svtype> enum. Test these flags with the C<SvTYPE> macro.
2200 Used to upgrade an SV to a more complex form. Uses C<sv_upgrade> to perform
2201 the upgrade if necessary. See C<svtype>.
2203 bool SvUPGRADE _((SV* sv, svtype mt));
2207 Upgrade an SV to a more complex form. Use C<SvUPGRADE>. See C<svtype>.
2211 This is the C<undef> SV. Always refer to this as C<&sv_undef>.
2215 Unsets the RV status of the SV, and decrements the refcount of whatever was
2216 being referenced by the RV. This can almost be thought of as a reversal of
2217 C<newSVrv>. See C<SvROK_off>.
2219 void sv_unref _((SV* sv));
2223 Tells an SV to use C<ptr> to find its string value. Normally the string is
2224 stored inside the SV but sv_usepvn allows the SV to use an outside string.
2225 The C<ptr> should point to memory that was allocated by C<malloc>. The
2226 string length, C<len>, must be supplied. This function will realloc the
2227 memory pointed to by C<ptr>, so that pointer should not be freed or used by
2228 the programmer after giving it to sv_usepvn.
2230 void sv_usepvn _((SV* sv, char* ptr, STRLEN len));
2234 This is the C<true> SV. See C<sv_no>. Always refer to this as C<&sv_yes>.
2238 Variable which is setup by C<xsubpp> to designate the object in a C++ XSUB.
2239 This is always the proper type for the C++ object. See C<CLASS> and
2240 L<perlxs/"Using XS With C++">.
2244 Converts the specified character to lowercase.
2246 int toLOWER (char c)
2250 Converts the specified character to uppercase.
2252 int toUPPER (char c)
2256 This is the XSUB-writer's interface to Perl's C<warn> function. Use this
2257 function the same way you use the C C<printf> function. See C<croak()>.
2261 Push an integer onto the stack, extending the stack if necessary. See
2268 Push a double onto the stack, extending the stack if necessary. See
2275 Push a string onto the stack, extending the stack if necessary. The C<len>
2276 indicates the length of the string. See C<PUSHp>.
2278 XPUSHp(char *c, int len)
2282 Push an SV onto the stack, extending the stack if necessary. See C<PUSHs>.
2288 Macro to declare an XSUB and its C parameter list. This is handled by
2293 Return from XSUB, indicating number of items on the stack. This is usually
2294 handled by C<xsubpp>.
2298 =item XSRETURN_EMPTY
2300 Return an empty list from an XSUB immediately.
2306 Return an integer from an XSUB immediately. Uses C<XST_mIV>.
2312 Return C<&sv_no> from an XSUB immediately. Uses C<XST_mNO>.
2318 Return an double from an XSUB immediately. Uses C<XST_mNV>.
2324 Return a copy of a string from an XSUB immediately. Uses C<XST_mPV>.
2326 XSRETURN_PV(char *v);
2328 =item XSRETURN_UNDEF
2330 Return C<&sv_undef> from an XSUB immediately. Uses C<XST_mUNDEF>.
2336 Return C<&sv_yes> from an XSUB immediately. Uses C<XST_mYES>.
2342 Place an integer into the specified position C<i> on the stack. The value is
2343 stored in a new mortal SV.
2345 XST_mIV( int i, IV v );
2349 Place a double into the specified position C<i> on the stack. The value is
2350 stored in a new mortal SV.
2352 XST_mNV( int i, NV v );
2356 Place C<&sv_no> into the specified position C<i> on the stack.
2362 Place a copy of a string into the specified position C<i> on the stack. The
2363 value is stored in a new mortal SV.
2365 XST_mPV( int i, char *v );
2369 Place C<&sv_undef> into the specified position C<i> on the stack.
2371 XST_mUNDEF( int i );
2375 Place C<&sv_yes> into the specified position C<i> on the stack.
2381 The version identifier for an XS module. This is usually handled
2382 automatically by C<ExtUtils::MakeMaker>. See C<XS_VERSION_BOOTCHECK>.
2384 =item XS_VERSION_BOOTCHECK
2386 Macro to verify that a PM module's $VERSION variable matches the XS module's
2387 C<XS_VERSION> variable. This is usually handled automatically by
2388 C<xsubpp>. See L<perlxs/"The VERSIONCHECK: Keyword">.
2392 The XSUB-writer's interface to the C C<memzero> function. The C<d> is the
2393 destination, C<n> is the number of items, and C<t> is the type.
2395 (void) Zero( d, n, t );
2401 Jeff Okamoto E<lt>F<okamoto@corp.hp.com>E<gt>
2403 With lots of help and suggestions from Dean Roehrich, Malcolm Beattie,
2404 Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil
2405 Bowers, Matthew Green, Tim Bunce, and Spider Boardman.
2407 API Listing by Dean Roehrich E<lt>F<roehrich@cray.com>E<gt>.
2411 Version 22: 1996/9/23