XS Fun

Sawyer X ( )@PerlSawyer

XS is...A glue layer between Perl and C/C++Sections, macros, functionsRequires knowledge with C, Perl API, XS, typemapsWritten by our very bestComplex, difficult, strenuous, laborious, painful, formidable (additional words can be found in )An impediment to Modern Perl

thesaurus.com

XS ismisunderstood

No need to be an expertBasic Perl API is simpleXS is not too difficultLots of optionsAll documented

Except...... except those that aren't documented... except that the official tutorial sucks... except that there's no better (or any other full) tutorial(at least not one I could find)

I guess I'll write one then!

XS FunA tutorial making XS funStarts easy, progresses slowlySplit to chapters, each taking a small taskA lot of explanations for beginnersAll examples work

FeaturesAlready on GithubA few chapters already coveredFunctions (XS, C)ConstructorSimple methods

MissingComplex methodsConverting objects with typemapsAdvanced XS

Quick glossarySV = Scalar Value

Of:IV = Integer Value (my $i = -30)UV = Unsigned Integer Value (my $u = 3000...)NV = Double Value (my $d = 30.771)PV = String Value (my $s = 'hello world')SV = (another) Scalar Value

AH = Array Value (my @a = qw<hello world>)HV = Hash Value (my %h = ( hello => 'world' ))RV = Reference Value (my $hashref = \%h)That's it for now

Examples

XSFun.pmpackage XSFun;use strict;use warnings;

use Exporter;use XSLoader;

use base 'Exporter';

our $VERSION = '0.001';our %EXPORT_TAGS = ( 'all' => [qw<get_version>] );our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );

XSLoader::load( 'XSFun', $VERSION );

1;

XSFun.xs#include "EXTERN.h"#include "perl.h"#include "XSUB.h"#include "ppport.h"

MODULE = XSFun PACKAGE = XSFun

doubleadd_numbers(double a, double b) CODE: RETVAL = a + b; OUTPUT: RETVAL

SV *add_numbers_perl(SV *a, SV *b) CODE: { const double sum = SvNV(a) + SvNV(b); RETVAL = newSVnv(sum); } OUTPUT: RETVAL

XSFun.xs (more)#include <chromaprint.h>

/* in the code section */const char *get_version() CODE: RETVAL = chromaprint_get_version(); OUTPUT: RETVAL

# in version.t:

use XSFun ':all';is( get_version(), '6.0.0', 'chromaprint version is 6.0.0' );

t/version.t .. okAll tests successful.Files=1, Tests=1, 0 wallclock secs ( 0.03 usr 0.01 sys + 0.02 cusr 0.00 csys = 0.06 CPU)Result: PASS

Audio::ChromaprintInterface to Chromaprint library

Audio/Chromaprint.pmpackage Audio::Chromaprint;

use strict;use warnings;use XSLoader;

our $VERSION = '0.001';

XSLoader::load( 'Audio::Chromaprint', $VERSION );

1;

Chromaprint.xs#include "EXTERN.h"#include "perl.h"#include "XSUB.h"#include "ppport.h"

#include <chromaprint.h>

MODULE = Audio::Chromaprint PACKAGE = Audio::Chromaprint

Chromaprint.xsconst char *version(SV *self) CODE: RETVAL = chromaprint_get_version(); OUTPUT: RETVAL

Constructor# In Perl:sub new { bless {}, shift }

# or...sub new { my $class = shift; # or $_[0] my %hash = (); my $self = \%hash; return bless $self, $class;}

# Pure-Perlsub new { my $class = shift; # or $_[0] my %hash = (); my $self = \%hash; return bless $self, $class;}

/* in XS */SV *new( const char *class ) CODE: /* Create a hash */ HV* hash = newHV();

/* Create a reference to the hash */ SV* const self = newRV_noinc( (SV *)hash );

/* bless into the proper package */ RETVAL = sv_bless( self, gv_stashpv( class, 0 ) ); OUTPUT: RETVAL

ConclusionsXS is not that complex

XS can be funYou can do it!

Thank you

Homework:github.com/xsawyerx/xs-funperldoc perlgutsperldoc perlapiperldoc perlxs