Igor Sysoev wrote:
>
>> Fairly, there is even more speedup hacks. For example, you can use
>> TARG-macros, if you allocate string with Newx() call.
>
> Could you explain in detail ?
If you return exactly one scalar then efficient way is to use
TARG-macros. Every opcode and XSUB-routine has specially assigned SV,
which are created/freed only once. You can use it to place return value
on stack. Mega-optimized variant can be next:
MODULE = XXX
PROTOTYPES: DISABLE
void
myfunc(in)
CODE:
{
dXSTARG;
char *res;
STRLEN len_res;
// build *res ...
sv_setpvn(TARG, res, len_res); // string IS copied!
ST(0) = TARG; // fairly, we must call
// XSprePUSH; PUSHTARG;
// but it is not required for our simplest case
// SvSETMAGIC(TARG); // Skipped, because we return only
//simple scalars without any magic
XSRETURN(1);
}
If you don't want use sv_setpvn() then you can use
SvPV_set/SvFAKE_on/... from my previous email.
TARG can not be used for multiple return values.
See "man perlguts":
"XSUBs and the Argument Stack"
"Putting a C value on Perl stack"
for futher reference.
> By the way, is it possible to avoid creating my mortal SV and create just
> perl SV ?
If you don't want to create new SV at all - you can modify passed
arguments in-place.
I.e. instead of:
my $src = "aaa";
my $dst = my_uppercase($src);
# invariant: $dst eq 'AAA'
you can use:
my $src = "aaa";
my_uppercase($src);
# invariant: $src eq 'AAA'
--
Sergey Skvortsov
mailto: [EMAIL PROTECTED]
