On Apr 5, 2006, at 1:02 PM, Igor Sysoev wrote:
is the effective way to return data from XS to perl without
unnecessary
memory coping ?
Assuming that your C function can write to a passed in char* and that
you can know the length in advance, the best way is to create an SV
with a string buffer of sufficient length, write to the that buffer
directly, and put that SV on the stack.
SV*
efficient_read_from_c()
PREINIT:
SV *fresh_sv;
STRLEN len;
char *ptr;
CODE:
len = get_len();
SV* fresh_sv = newSV(len);
SvPOK_on(fresh_sv);
ptr = SvPVX(fresh_sv);
if (get_string(ptr))
SvCUR_set(fresh_sv, len);
*SvEND(fresh_sv) = '\0';
RETVAL = fresh_sv;
OUTPUT: RETVAL
This same subject was just discussed at some length on PerlMonks:
<http://www.perlmonks.org/index.pl?node_id=541706>.
Marvin Humphrey
Rectangular Research
http://www.rectangular.com/
