#!/usr/bin/perl
#gpio.pm
#Copyright (c) 2012 Ben S. Eishen
#This library is free software; you can redistribute it and/or
#modify it under the terms of the GNU Lesser General Public
#License as published by the Free Software Foundation; either
#version 2.1 of the License, or (at your option) any later version.

#This library is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
#Lesser General Public License for more details.

package gpio;

require Exporter;
@ISA = qw(Exporter);
@EXPORT_OK = qw(export, set_dir, set_value, get_value);

use constant SYSFS_GPIO_DIR => '/sys/class/gpio';

#gpio_export(24);
#gpio_set_dir(24,1);
#gpio_set_value(24,0);
#print gpio_get_value(24);

sub export{
    my ($gpio) = @_;
    open(FILE, ">@{[SYSFS_GPIO_DIR]}/export") || die "Could not open @{[SYSFS_GPIO_DIR]}/export for GPIO pin ${gpio}";
    print FILE $gpio;
    close(FILE);
}

sub unexport{
    my $gpio = @_;
    open(FILE, ">@{[SYSFS_GPIO_DIR]}/unexport") || die "Could not open @{[SYSFS_GPIO_DIR]}/unexport for GPIO pin ${gpio}";
    print FILE $gpio;
    close(FILE);
}

sub set_dir{
    my ($gpio,$out_flag) = @_;
    open(FILE, ">@{[SYSFS_GPIO_DIR]}/gpio${gpio}/direction") || die "Could not open file @{[SYSFS_GPIO_DIR]}/gpio${gpio}/direction for GPIO pin ${gpio}";
    if($out_flag){
        print FILE "out";
    }
    else{
        print FILE "in";
    }
    close(FILE);
}

sub set_value{
    my ($gpio, $value) = @_;
    open(FILE, ">@{[SYSFS_GPIO_DIR]}/gpio${gpio}/value") || die "Could not open file for setting the value, GPIO pin ${gpio}";
    if($value){
        print FILE 1;
    }
    else{
        print FILE 0;
    }
    close(FILE);
}

sub get_value{
    my ($gpio) = @_;
    my $value;
    open(FILE, "<@{[SYSFS_GPIO_DIR]}/gpio${gpio}/value") || die "Could not open file for fetching the value, GPIO pin ${gpio}";
    read(FILE, $value, 1);
    close(FILE);
    return $value;
}

sub set_edge{
    my ($gpio,$edge) = @_;
    open(FILE, ">@{[SYSFS_GPIO_DIR]}/gpio${gpio}/edge") || die "Could not open file for setting the edge, GPIO pin ${gpio}";
    print FILE $edge;
    close(FILE);
}

sub fd_open{
    my ($gpio) = @_;
    open(FILE, "<@{[SYSFS_GPIO_DIR]}/gpio${gpio}/value") || die "Could not open file, GPIO PIN ${gpio}";
    return FILE;
}

sub fd_close{
    my($fd) = @_;
    close($fd) || die "Could not close file!";
}

1;