How to use zlib (a C library) from Perl with SPVM

#spvm #perl #zlib #c

How to use zlib (a C library) from Perl with SPVM.

See an example to bind zlib to SPVM

SPVM provides a way to bind C language libraries and call them from Perl.

When binding C libraries to Perl, you typically write XS, but SPVM offers an alternative approach.

MyZlib.spvm

class MyZlib {
  native static method test : void ($ouf_file : string);
}

MyZlib.c

#include "spvm_native.h"
#include<stdio.h>

#include "zlib.h"

static const char* FILE_NAME = "MyZlib.c";

int32_t SPVM__MyZlib__test(SPVM_ENV* env, SPVM_VALUE* stack) {

  void* obj_out_file = stack[0].oval;

  if (!obj_out_file){
    return env->die(env, stack, "$ouf_file must be defined.", __func__, FILE_NAME, __LINE__);
  }

  const char* out_file = env->get_chars(env, stack, obj_out_file);

  char buf[]="0123456789abcdefghijklmnopqrstuvwxyz\n";
  int cnt = 0;
  gzFile zp;

  zp = gzopen(out_file, "w9");
  if(zp == NULL){
    return env->die(env, stack, "gzopen failed.", "MyZlib.c", __func__, FILE_NAME, __LINE__);
  }

  for(cnt = 0; cnt < 100; cnt++){
    gzputs(zp, buf);
  }

  gzclose(zp);

  return 0;
}

MyZlib.config

use strict;
use warnings;

use SPVM::Builder::Config;

my $config = SPVM::Builder::Config->new_gnu99(file => __FILE__);

$config->add_lib('z');

$config;

zlib.pl

use strict;
use warnings;

use FindBin;
use lib "$FindBin::Bin/lib";

use SPVM 'MyZlib';

my $out_file = "$ENV{HOME}/tmp/output.gz";

SPVM::MyZlib->test($out_file);

A compressed file "output.gz" will be output.