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#!/usr/bin/perl -w
use strict;
sub linear_to_srgb
{
my ($c) = @_;
if ($c < 0.0031308)
{
return $c * 12.92;
}
else
{
return 1.055 * $c ** (1.0/2.4) - 0.055;
}
}
sub srgb_to_linear
{
my ($c) = @_;
if ($c < 0.04045)
{
return $c / 12.92;
}
else
{
return (($c + 0.055) / 1.055) ** 2.4
}
}
my @linear_to_srgb;
for my $linear (0 .. 4095)
{
my $srgb = int(linear_to_srgb($linear / 4095.0) * 255.0 + 0.5);
push @linear_to_srgb, $srgb;
}
my @srgb_to_linear;
for my $srgb (0 .. 255)
{
my $linear = int(srgb_to_linear($srgb / 255.0) * 65535.0 + 0.5);
push @srgb_to_linear, $linear;
}
# Ensure that we have a lossless sRGB and back conversion loop.
# some of the darkest shades need a little bias -- maximum is just
# 5 increments out of 16. This gives us useful property with
# least amount of error in the sRGB-to-linear table, and keeps the actual
# table lookup in the other direction as simple as possible.
for my $srgb (0 .. $#srgb_to_linear)
{
my $add = 0;
while (1)
{
my $linear = $srgb_to_linear[$srgb];
my $srgb_lossy = $linear_to_srgb[$linear >> 4];
last if $srgb == $srgb_lossy;
# Add slight bias to this component until it rounds correctly
$srgb_to_linear[$srgb] ++;
$add ++;
}
die "Too many adds at $srgb" if $add > 5;
}
print <<"PROLOG";
/* WARNING: This file is generated by $0.
* Please edit that file instead of this one.
*/
#include <stdint.h>
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "pixman-private.h"
PROLOG
print "const uint8_t linear_to_srgb[" . @linear_to_srgb . "] =\n";
print "{\n";
for my $linear (0 .. $#linear_to_srgb)
{
if (($linear % 10) == 0)
{
print "\t";
}
print sprintf("%d, ", $linear_to_srgb[$linear]);
if (($linear % 10) == 9)
{
print "\n";
}
}
print "\n};\n";
print "\n";
print "const uint16_t srgb_to_linear[" . @srgb_to_linear . "] =\n";
print "{\n";
for my $srgb (0 .. $#srgb_to_linear)
{
if (($srgb % 10) == 0)
{
print "\t";
}
print sprintf("%d, ", $srgb_to_linear[$srgb]);
if (($srgb % 10) == 9)
{
print "\n";
}
}
print "\n};\n";
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