The document discusses various ways to embed Perl in C and C in Perl. It provides an overview of embedding Perl in C using ExtUtils::Embed, B::C, and XS. It also covers embedding C code in Perl using Inline::C and XS. Finally, it demonstrates examples of calling Perl functions from C code and evaluating Perl code from embedded C programs.

1. Embedding Perl in C and
the other way around
Marian Marinov(mm@1h.com
Co-Founder and CIO of 1H Ltd.

2. Embedding C in Perl

3. The XS way...
It cannot be seen, cannot be felt,
Cannot be heard, cannot be smelt.
It lies behind stars and under hills,
And empty holes it fills.
- J.R.R. Tolkien, The Hobbit
Answer: dark.

4. XS Docs
● perlman:perlxstut
● man perlxs
● man perlguts
● man perlapi
● man h2xs

5. XS Basics
● SV – Scalar Value SV* newSVsv(SV*);
● AV – Array Value
● HV – Hash Value
● IV – Integer Value SV* newSViv(IV);
● UV – Unsigned Integer Value SV* newSVuv(UV);
● NV – Double Value SV* newSVnv(double);
● PV – String Value
●SV* newSVpv(const char*, STRLEN);
●SV* newSVpvn(const char*, STRLEN);
●SV* newSVpvf(const char*, ...);
SvIV(SV*)
SvUV(SV*)
SvNV(SV*)
SvPV(SV*, STRLEN len)
SvPV_nolen(SV*)

6. Inline::C
$ cat inline.pl
#!/usr/bin/perl
use Inline C=>'
void some_func() {
printf("Hello Worldn");
}';
&some_func
$ ./inline.pl
Hello World
Examples from Inline::C-Cookbook

7. fun way of using Inline::C
$ cat perl­sign.pl
#!/usr/bin/perl
use Inline C=>'
void C() {
int m,u,e=0;float l,_,I;
for(;1840­e;putchar((++e>907&&942>e?61­m:u)
["n)moc.isc@rezneumb(rezneuM drahnreB"]))
for(u=_=l=0;79­(m=e%80)&&I*l+_*_<6&&26­+
+u;_=2*l*_+e/80*.09­1,l=I)
I=l*l­_*_­2+m/27.;
}';
&C

8. mmmmmmmmooooooooooooooooooooooooocccccccccc....is@zrre i.cccccccoooooooooommmmm
mmmmmmoooooooooooooooooooooooccccccccccc.....iiscrr n@csi...ccccccoooooooooommm
mmmmooooooooooooooooooooooccccccccccc....iiiss@n zMesii....cccccoooooooooom
mmooooooooooooooooooooocccccccccc....iisssssc@rn erccsiiiii..ccccooooooooo
moooooooooooooooooocccccccc.......iis@e uMeu r e r@@@ezs..cccoooooooo
oooooooooooooooccccccc.........iiiisc@z e eci..cccooooooo
ooooooooooccccccc..iiiiiiiiiiiiisscz z z@sii.ccccoooooo
oooooccccccccc...iicz@ccccz@ccccccrrr s..cccoooooo
ooocccccccc.....iisc@eb bnneree eci..ccccooooo
occcccccc.....iisccrnb m nci..ccccooooo
ccc....iiiiisss@emee( cii..cccccoooo
iscc@@beremeene( Bernhard Muenzer(bmuenzer@csi.com) ercsi...cccccoooo
c....iiiiiisssc@e rnz esi...cccccoooo
occccccc....iiiscc@rb ( esi..ccccooooo
oocccccccc......iisc@z bneze z@i..ccccooooo
ooooocccccccc....ii@er@@@@nr@cccc@e es..cccoooooo
oooooooooccccccc...@siiiiiiiiisssscnM urcsi..cccoooooo
ooooooooooooooccccccc..........iiiisc@e zsi..cccooooooo
mooooooooooooooooocccccccc.......iiis@ nu er eznri.cccoooooooo
mmoooooooooooooooooooocccccccccc....issc@ccc@@rn er@cssiiiss..cccooooooooo
mmmmoooooooooooooooooooooccccccccccc....iiiisc@z rrsii.....ccccoooooooooom
mmmmmooooooooooooooooooooooocccccccccccc....iis@rz rrcsi....ccccccoooooooooomm
mmmmmmmmoooooooooooooooooooooooocccccccccc....iisceeeusi..cccccccooooooooommmmm

9. Multiple Return Values
print map {"$_n"} get_localtime(time);
use Inline C => <<'END_OF_C_CODE';
#include <time.h>
void get_localtime(int utc) {
struct tm *ltime = localtime(&utc);
Inline_Stack_Vars;
Inline_Stack_Reset;
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_year)));
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_mon)));
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_mday)));
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_hour)));
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_min)));
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_sec)));
Inline_Stack_Push(sv_2mortal(newSViv(ltime->tm_isdst)));
Inline_Stack_Done;
}
END_OF_C_CODE

10. Variable Argument Lists
greet(qw(Sarathy Jan Sparky Murray Mike));
use Inline C => <<'END_OF_C_CODE';
void greet(SV* name1, ...) {
Inline_Stack_Vars;
int i;
for (i = 0; i < Inline_Stack_Items; i++)
printf("Hello %s!n",
SvPV(Inline_Stack_Item(i), PL_na));
Inline_Stack_Void;
}
END_OF_C_CODE

11. Another way of using Inline::C
use Inline C;
$vp = string_scan($text); # call our function
__END__
__C__
/*
* Our C code goes here
*/
int string_scan(char* str) {
}

12. Embedding Perl in C

13. How you can do it?
● ExtUtils::Embed
perl -MExtUtils::Embed -e ccopts -e ldopts
● B::C
● The only way... XS

14. Docs
man perlembed
man perlcall
man perlguts
man perlapi
man perlxs

15. B::C/perlcc
● Works with Perl 5.6.0
● Works with Perl 5.13.x
#!/usr/bin/perl
use strict;
use warnings;
use lib '.';
use parse_config;
my $a = 'some text';
my $b = 13;
my %config = parse_config('/etc/guardian.conf');
#my %config = ( df => 13, hj => 18);
printf "%s %dn", $a, $b;
while (my ($k,$v) = each %config) {
print "$k :: $vn";
}

16. $ perlcc -o em em.pl
$ ./em
Segmentation fault
$ perlcc -o em em.pl
$ ./em
some text 13
df :: 13
hj :: 18

17. #include "embed.h"
int main (int argc, char **argv, char **env) {
char *embedding[] = { "", "-e", "0" };
unsigned char *perlPlain;
size_t len = 0;
int err = 0;
PERL_SYS_INIT3(&argc,&argv,&env);
my_perl = perl_alloc();
perl_construct( my_perl );
perl_parse(my_perl, xs_init, 3, embedding, NULL);
PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
perl_run(my_perl);
perlPlain=spc_base64_decode(&perl64,&len,0,&err);
eval_pv(perlPlain, TRUE);
perl_destruct(my_perl);
perl_free(my_perl);
PERL_SYS_TERM();
return 0;
}

18. #ifndef _EMBED_H
#define _EMBED_H
#include <EXTERN.h>
#include <perl.h>
#include "base64.h"
#include "code_64.h"
static PerlInterpreter *my_perl;
static void xs_init (pTHX);
EXTERN_C void boot_DynaLoader (pTHX_ CV* cv);
EXTERN_C void boot_Socket (pTHX_ CV* cv);
EXTERN_C void xs_init(pTHX) {
char *file = __FILE__;
/* DynaLoader is a special case */
newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader,
file);
}
#endif

19. $ ./embed --version
This is perl, v5.10.1 (*) built for i386-linux-thread-multi
Copyright 1987-2009, Larry Wall
Perl may be copied only under the terms of either the Artistic
License or the
GNU General Public License, which may be found in the Perl 5
source kit.
Complete documentation for Perl, including FAQ lists, should be
found on
this system using "man perl" or "perldoc perl". If you have
access to the
Internet, point your browser at http://www.perl.org/, the Perl
Home Page.

20. # perl -MExtUtils::Embed -e ccopts -e ldopts
-Wl,-E -Wl,-rpath,/usr/lib/perl5/5.8.8/i386-linux-thread-
multi/CORE -L/usr/local/lib /usr/lib/perl5/5.8.8/i386-linux-
thread-multi/auto/DynaLoader/DynaLoader.a
-L/usr/lib/perl5/5.8.8/i386-linux-thread-multi/CORE -lperl
-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe
-Wdeclaration-after-statement -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm
-I/usr/lib/perl5/5.8.8/i386-linux-thread-multi/CORE
# gcc -o embed embed.c $(perl -MExtUtils::Embed -e ccopts -e
ldopts)

21. call_argv("showtime", G_DISCARD | G_NOARGS, args);
vs.
eval_pv(perlPlain, TRUE);
/** Treat $a as an integer **/
eval_pv("$a = 3; $a **= 2", TRUE);
printf("a = %dn", SvIV(get_sv("a", 0)));
/** Treat $a as a float **/
eval_pv("$a = 3.14; $a **= 2", TRUE);
printf("a = %fn", SvNV(get_sv("a", 0)));
/** Treat $a as a string **/
eval_pv("$a = 'rekcaH lreP rehtonA tsuJ'; $a = reverse($a);",
TRUE);
printf("a = %sn", SvPV_nolen(get_sv("a", 0)));