SV* newSVrv(SV* rv, const char* classname);
-Copies integer or double into an SV whose reference is C<rv>. SV is blessed
+Copies integer, unsigned integer or double into an SV whose reference is C<rv>. SV is blessed
if C<classname> is non-null.
SV* sv_setref_iv(SV* rv, const char* classname, IV iv);
+ SV* sv_setref_uv(SV* rv, const char* classname, UV uv);
SV* sv_setref_nv(SV* rv, const char* classname, NV iv);
Copies the pointer value (I<the address, not the string!>) into an SV whose
These macros automatically adjust the stack for you, if needed. Thus, you
do not need to call C<EXTEND> to extend the stack.
+However, see L</Putting a C value on Perl stack>
For more information, consult L<perlxs> and L<perlxstut>.
instances of the size of the C<type> data structure (using the C<sizeof>
function).
-Here is a handy table of equivalents between ordinary C and Perl's
-memory abstraction layer:
-
- Instead Of: Use:
-
- malloc New
- calloc Newz
- realloc Renew
- memcopy Copy
- memmove Move
- free Safefree
- strdup savepv
- strndup savepvn (Hey, strndup doesn't exist!)
- memcpy/*(struct foo *) StructCopy
-
=head2 PerlIO
The most recent development releases of Perl has been experimenting with
directly used in some opcodes, as well as indirectly in zillions of
others, which use it via C<(X)PUSH[pni]>.
+Because the target is reused, you must be careful when pushing multiple
+values on the stack. The following code will not do what you think:
+
+ XPUSHi(10);
+ XPUSHi(20);
+
+This translates as "set C<TARG> to 10, push a pointer to C<TARG> onto
+the stack; set C<TARG> to 20, push a pointer to C<TARG> onto the stack".
+At the end of the operation, the stack does not contain the values 10
+and 20, but actually contains two pointers to C<TARG>, which we have set
+to 20. If you need to push multiple different values, use C<XPUSHs>,
+which bypasses C<TARG>.
+
+On a related note, if you do use C<(X)PUSH[npi]>, then you're going to
+need a C<dTARG> in your variable declarations so that the C<*PUSH*>
+macros can make use of the local variable C<TARG>.
+
=head2 Scratchpads
The question remains on when the SVs which are I<target>s for opcodes
something like this:
ifdef PERL_IMPLICIT_CONTEXT
- define sv_setsv(a,b) Perl_sv_setsv(aTHX_ a, b)
+ define sv_setsv(a,b) Perl_sv_setsv(aTHX_ a, b)
/* can't do this for vararg functions, see below */
else
- define sv_setsv Perl_sv_setsv
+ define sv_setsv Perl_sv_setsv
endif
This works well, and means that XS authors can gleefully write:
The second, more efficient way is to use the following template for
your Foo.xs:
- #define PERL_NO_GET_CONTEXT /* we want efficiency */
- #include "EXTERN.h"
- #include "perl.h"
- #include "XSUB.h"
+ #define PERL_NO_GET_CONTEXT /* we want efficiency */
+ #include "EXTERN.h"
+ #include "perl.h"
+ #include "XSUB.h"
static my_private_function(int arg1, int arg2);
- static SV *
- my_private_function(int arg1, int arg2)
- {
- dTHX; /* fetch context */
- ... call many Perl API functions ...
- }
+ static SV *
+ my_private_function(int arg1, int arg2)
+ {
+ dTHX; /* fetch context */
+ ... call many Perl API functions ...
+ }
[... etc ...]
- MODULE = Foo PACKAGE = Foo
+ MODULE = Foo PACKAGE = Foo
- /* typical XSUB */
+ /* typical XSUB */
- void
- my_xsub(arg)
- int arg
- CODE:
- my_private_function(arg, 10);
+ void
+ my_xsub(arg)
+ int arg
+ CODE:
+ my_private_function(arg, 10);
Note that the only two changes from the normal way of writing an
extension is the addition of a C<#define PERL_NO_GET_CONTEXT> before
the Perl guts:
- #define PERL_NO_GET_CONTEXT /* we want efficiency */
- #include "EXTERN.h"
- #include "perl.h"
- #include "XSUB.h"
+ #define PERL_NO_GET_CONTEXT /* we want efficiency */
+ #include "EXTERN.h"
+ #include "perl.h"
+ #include "XSUB.h"
/* pTHX_ only needed for functions that call Perl API */
static my_private_function(pTHX_ int arg1, int arg2);
- static SV *
- my_private_function(pTHX_ int arg1, int arg2)
- {
- /* dTHX; not needed here, because THX is an argument */
- ... call Perl API functions ...
- }
+ static SV *
+ my_private_function(pTHX_ int arg1, int arg2)
+ {
+ /* dTHX; not needed here, because THX is an argument */
+ ... call Perl API functions ...
+ }
[... etc ...]
- MODULE = Foo PACKAGE = Foo
+ MODULE = Foo PACKAGE = Foo
- /* typical XSUB */
+ /* typical XSUB */
- void
- my_xsub(arg)
- int arg
- CODE:
- my_private_function(aTHX_ arg, 10);
+ void
+ my_xsub(arg)
+ int arg
+ CODE:
+ my_private_function(aTHX_ arg, 10);
This implementation never has to fetch the context using a function
call, since it is always passed as an extra argument. Depending on
formatting codes like C<%d>, C<%ld>, C<%f>, you should use the
following macros for portability
- IVdf IV in decimal
- UVuf UV in decimal
- UVof UV in octal
- UVxf UV in hexadecimal
- NVef NV %e-like
- NVff NV %f-like
- NVgf NV %g-like
+ IVdf IV in decimal
+ UVuf UV in decimal
+ UVof UV in octal
+ UVxf UV in hexadecimal
+ NVef NV %e-like
+ NVff NV %f-like
+ NVgf NV %g-like
These will take care of 64-bit integers and long doubles.
For example:
- printf("IV is %"IVdf"\n", iv);
+ printf("IV is %"IVdf"\n", iv);
The IVdf will expand to whatever is the correct format for the IVs.
Because pointer size does not necessarily equal integer size,
use the follow macros to do it right.
- PTR2UV(pointer)
- PTR2IV(pointer)
- PTR2NV(pointer)
- INT2PTR(pointertotype, integer)
+ PTR2UV(pointer)
+ PTR2IV(pointer)
+ PTR2NV(pointer)
+ INT2PTR(pointertotype, integer)
For example:
- IV iv = ...;
- SV *sv = INT2PTR(SV*, iv);
+ IV iv = ...;
+ SV *sv = INT2PTR(SV*, iv);
and
- AV *av = ...;
- UV uv = PTR2UV(av);
+ AV *av = ...;
+ UV uv = PTR2UV(av);
=head2 Source Documentation
projects / p5sagit/p5-mst-13.2.git / blobdiff