#!/usr/bin/perl -w
#
# A script to generate optimized C blitters for Simple DirectMedia Layer
# http://www.libsdl.org/

use warnings;
use strict;

my %file;

# The formats potentially supported by this script:
# SDL_PIXELFORMAT_INDEX8
# SDL_PIXELFORMAT_RGB332
# SDL_PIXELFORMAT_RGB444
# SDL_PIXELFORMAT_RGB555
# SDL_PIXELFORMAT_ARGB4444
# SDL_PIXELFORMAT_ARGB1555
# SDL_PIXELFORMAT_RGB565
# SDL_PIXELFORMAT_RGB24
# SDL_PIXELFORMAT_BGR24
# SDL_PIXELFORMAT_RGB888
# SDL_PIXELFORMAT_BGR888
# SDL_PIXELFORMAT_ARGB8888
# SDL_PIXELFORMAT_RGBA8888
# SDL_PIXELFORMAT_ABGR8888
# SDL_PIXELFORMAT_BGRA8888
# SDL_PIXELFORMAT_ARGB2101010

# The formats we're actually creating blitters for:
my @src_formats = (
    "RGB888",
    "BGR888",
    "ARGB8888",
    "RGBA8888",
    "ABGR8888",
    "BGRA8888",
);
my @dst_formats = (
    "RGB888",
    "BGR888",
    "ARGB8888",
);

my %format_size = (
    "RGB888" => 4,
    "BGR888" => 4,
    "ARGB8888" => 4,
    "RGBA8888" => 4,
    "ABGR8888" => 4,
    "BGRA8888" => 4,
);

my %format_type = (
    "RGB888" => "Uint32",
    "BGR888" => "Uint32",
    "ARGB8888" => "Uint32",
    "RGBA8888" => "Uint32",
    "ABGR8888" => "Uint32",
    "BGRA8888" => "Uint32",
);

my %get_rgba_string = (
    "RGB888" => "_R = (Uint8)(_pixel >> 16); _G = (Uint8)(_pixel >> 8); _B = (Uint8)_pixel; _A = 0xFF;",
    "BGR888" => "_B = (Uint8)(_pixel >> 16); _G = (Uint8)(_pixel >> 8); _R = (Uint8)_pixel; _A = 0xFF;", "ARGB8888" => "_A = (Uint8)(_pixel >> 24); _R = (Uint8)(_pixel >> 16); _G = (Uint8)(_pixel >> 8); _B = (Uint8)_pixel;",
    "RGBA8888" => "_R = (Uint8)(_pixel >> 24); _G = (Uint8)(_pixel >> 16); _B = (Uint8)(_pixel >> 8); _A = (Uint8)_pixel;",
    "ABGR8888" => "_A = (Uint8)(_pixel >> 24); _B = (Uint8)(_pixel >> 16); _G = (Uint8)(_pixel >> 8); _R = (Uint8)_pixel;",
    "BGRA8888" => "_B = (Uint8)(_pixel >> 24); _G = (Uint8)(_pixel >> 16); _R = (Uint8)(_pixel >> 8); _A = (Uint8)_pixel;",
);

my %set_rgba_string = (
    "RGB888" => "_pixel = ((Uint32)_R << 16) | ((Uint32)_G << 8) | _B;",
    "BGR888" => "_pixel = ((Uint32)_B << 16) | ((Uint32)_G << 8) | _R;",
    "ARGB8888" => "_pixel = ((Uint32)_A << 24) | ((Uint32)_R << 16) | ((Uint32)_G << 8) | _B;",
    "RGBA8888" => "_pixel = ((Uint32)_R << 24) | ((Uint32)_G << 16) | ((Uint32)_B << 8) | _A;",
    "ABGR8888" => "_pixel = ((Uint32)_A << 24) | ((Uint32)_B << 16) | ((Uint32)_G << 8) | _R;",
    "BGRA8888" => "_pixel = ((Uint32)_B << 24) | ((Uint32)_G << 16) | ((Uint32)_R << 8) | _A;",
);

sub open_file {
    my $name = shift;
    open(FILE, ">$name.new") || die "Cant' open $name.new: $!";
    print FILE <<__EOF__;
/* DO NOT EDIT!  This file is generated by sdlgenblit.pl */
/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2011 Sam Lantinga

    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.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken\@libsdl.org
*/
#include "SDL_config.h"

/* *INDENT-OFF* */

__EOF__
}

sub close_file {
    my $name = shift;
    print FILE <<__EOF__;
/* *INDENT-ON* */

/* vi: set ts=4 sw=4 expandtab: */
__EOF__
    close FILE;
    if ( ! -f $name || system("cmp -s $name $name.new") != 0 ) {
        rename("$name.new", "$name");
    } else {
        unlink("$name.new");
    }
}

sub output_copydefs
{
    print FILE <<__EOF__;
extern SDL_BlitFuncEntry SDL_GeneratedBlitFuncTable[];
__EOF__
}

sub output_copyfuncname
{
    my $prefix = shift;
    my $src = shift;
    my $dst = shift;
    my $modulate = shift;
    my $blend = shift;
    my $scale = shift;
    my $args = shift;
    my $suffix = shift;

    print FILE "$prefix SDL_Blit_${src}_${dst}";
    if ( $modulate ) {
        print FILE "_Modulate";
    }
    if ( $blend ) {
        print FILE "_Blend";
    }
    if ( $scale ) {
        print FILE "_Scale";
    }
    if ( $args ) {
        print FILE "(SDL_BlitInfo *info)";
    }
    print FILE "$suffix";
}

sub get_rgba
{
    my $prefix = shift;
    my $format = shift;
    my $string = $get_rgba_string{$format};
    $string =~ s/_/$prefix/g;
    if ( $prefix ne "" ) {
        print FILE <<__EOF__;
            ${prefix}pixel = *$prefix;
__EOF__
    } else {
        print FILE <<__EOF__;
            pixel = *src;
__EOF__
    }
    print FILE <<__EOF__;
            $string
__EOF__
}

sub set_rgba
{
    my $prefix = shift;
    my $format = shift;
    my $string = $set_rgba_string{$format};
    $string =~ s/_/$prefix/g;
    print FILE <<__EOF__;
            $string
            *dst = ${prefix}pixel;
__EOF__
}

sub output_copycore
{
    my $src = shift;
    my $dst = shift;
    my $modulate = shift;
    my $blend = shift;
    my $s = "";
    my $d = "";

    # Nice and easy...
    if ( $src eq $dst && !$modulate && !$blend ) {
        print FILE <<__EOF__;
            *dst = *src;
__EOF__
        return;
    }

    if ( $blend ) {
        get_rgba("src", $src);
        get_rgba("dst", $dst);
        $s = "src";
        $d = "dst";
    } else {
        get_rgba("", $src);
    }

    if ( $modulate ) {
        print FILE <<__EOF__;
            if (flags & SDL_COPY_MODULATE_COLOR) {
                ${s}R = (${s}R * modulateR) / 255;
                ${s}G = (${s}G * modulateG) / 255;
                ${s}B = (${s}B * modulateB) / 255;
            }
            if (flags & SDL_COPY_MODULATE_ALPHA) {
                ${s}A = (${s}A * modulateA) / 255;
            }
__EOF__
    }
    if ( $blend ) {
        print FILE <<__EOF__;
            if (flags & (SDL_COPY_BLEND|SDL_COPY_ADD)) {
                /* This goes away if we ever use premultiplied alpha */
                if (${s}A < 255) {
                    ${s}R = (${s}R * ${s}A) / 255;
                    ${s}G = (${s}G * ${s}A) / 255;
                    ${s}B = (${s}B * ${s}A) / 255;
                }
            }
            switch (flags & (SDL_COPY_BLEND|SDL_COPY_ADD)) {
            case SDL_COPY_BLEND:
                ${d}R = ${s}R + ((255 - ${s}A) * ${d}R) / 255;
                ${d}G = ${s}G + ((255 - ${s}A) * ${d}G) / 255;
                ${d}B = ${s}B + ((255 - ${s}A) * ${d}B) / 255;
                break;
            case SDL_COPY_ADD:
                ${d}R = ${s}R + ${d}R; if (${d}R > 255) ${d}R = 255;
                ${d}G = ${s}G + ${d}G; if (${d}G > 255) ${d}G = 255;
                ${d}B = ${s}B + ${d}B; if (${d}B > 255) ${d}B = 255;
                break;
            }
__EOF__
    }
    if ( $blend ) {
        set_rgba("dst", $dst);
    } else {
        set_rgba("", $dst);
    }
}

sub output_copyfunc
{
    my $src = shift;
    my $dst = shift;
    my $modulate = shift;
    my $blend = shift;
    my $scale = shift;

    output_copyfuncname("static void", $src, $dst, $modulate, $blend, $scale, 1, "\n");
    print FILE <<__EOF__;
{
    const int flags = info->flags;
__EOF__
    if ( $modulate ) {
        print FILE <<__EOF__;
    const Uint32 modulateR = info->r;
    const Uint32 modulateG = info->g;
    const Uint32 modulateB = info->b;
    const Uint32 modulateA = info->a;
__EOF__
    }
    if ( $blend ) {
        print FILE <<__EOF__;
    Uint32 srcpixel;
    Uint32 srcR, srcG, srcB, srcA;
    Uint32 dstpixel;
    Uint32 dstR, dstG, dstB, dstA;
__EOF__
    } elsif ( $modulate || $src ne $dst ) {
        print FILE <<__EOF__;
    Uint32 pixel;
    Uint32 R, G, B, A;
__EOF__
    }
    if ( $scale ) {
        print FILE <<__EOF__;
    int srcy, srcx;
    int posy, posx;
    int incy, incx;

    srcy = 0;
    posy = 0;
    incy = (info->src_h << 16) / info->dst_h;
    incx = (info->src_w << 16) / info->dst_w;

    while (info->dst_h--) {
        $format_type{$src} *src;
        $format_type{$dst} *dst = ($format_type{$dst} *)info->dst;
        int n = info->dst_w;
        srcx = -1;
        posx = 0x10000L;
        while (posy >= 0x10000L) {
            ++srcy;
            posy -= 0x10000L;
        }
        while (n--) {
            if (posx >= 0x10000L) {
                while (posx >= 0x10000L) {
                    ++srcx;
                    posx -= 0x10000L;
                }
                src = ($format_type{$src} *)(info->src + (srcy * info->src_pitch) + (srcx * $format_size{$src}));
__EOF__
        print FILE <<__EOF__;
            }
__EOF__
        output_copycore($src, $dst, $modulate, $blend);
        print FILE <<__EOF__;
            posx += incx;
            ++dst;
        }
        posy += incy;
        info->dst += info->dst_pitch;
    }
__EOF__
    } else {
        print FILE <<__EOF__;

    while (info->dst_h--) {
        $format_type{$src} *src = ($format_type{$src} *)info->src;
        $format_type{$dst} *dst = ($format_type{$dst} *)info->dst;
        int n = info->dst_w;
        while (n--) {
__EOF__
        output_copycore($src, $dst, $modulate, $blend);
        print FILE <<__EOF__;
            ++src;
            ++dst;
        }
        info->src += info->src_pitch;
        info->dst += info->dst_pitch;
    }
__EOF__
    }
    print FILE <<__EOF__;
}

__EOF__
}

sub output_copyfunc_h
{
}

sub output_copyinc
{
    print FILE <<__EOF__;
#include "SDL_video.h"
#include "SDL_blit.h"
#include "SDL_blit_auto.h"

__EOF__
}

sub output_copyfunctable
{
    print FILE <<__EOF__;
SDL_BlitFuncEntry SDL_GeneratedBlitFuncTable[] = {
__EOF__
    for (my $i = 0; $i <= $#src_formats; ++$i) {
        my $src = $src_formats[$i];
        for (my $j = 0; $j <= $#dst_formats; ++$j) {
            my $dst = $dst_formats[$j];
            for (my $modulate = 0; $modulate <= 1; ++$modulate) {
                for (my $blend = 0; $blend <= 1; ++$blend) {
                    for (my $scale = 0; $scale <= 1; ++$scale) {
                        if ( $modulate || $blend || $scale ) {
                            print FILE "    { SDL_PIXELFORMAT_$src, SDL_PIXELFORMAT_$dst, ";
                            my $flags = "";
                            my $flag = "";
                            if ( $modulate ) {
                                $flag = "SDL_COPY_MODULATE_COLOR | SDL_COPY_MODULATE_ALPHA";
                                if ( $flags eq "" ) {
                                    $flags = $flag;
                                } else {
                                    $flags = "$flags | $flag";
                                }
                            }
                            if ( $blend ) {
                                $flag = "SDL_COPY_BLEND | SDL_COPY_ADD";
                                if ( $flags eq "" ) {
                                    $flags = $flag;
                                } else {
                                    $flags = "$flags | $flag";
                                }
                            }
                            if ( $scale ) {
                                $flag = "SDL_COPY_NEAREST";
                                if ( $flags eq "" ) {
                                    $flags = $flag;
                                } else {
                                    $flags = "$flags | $flag";
                                }
                            }
                            if ( $flags eq "" ) {
                                $flags = "0";
                            }
                            print FILE "($flags), SDL_CPU_ANY,";
                            output_copyfuncname("", $src_formats[$i], $dst_formats[$j], $modulate, $blend, $scale, 0, " },\n");
                        }
                    }
                }
            }
        }
    }
    print FILE <<__EOF__;
    { 0, 0, 0, 0, NULL }
};

__EOF__
}

sub output_copyfunc_c
{
    my $src = shift;
    my $dst = shift;

    for (my $modulate = 0; $modulate <= 1; ++$modulate) {
        for (my $blend = 0; $blend <= 1; ++$blend) {
            for (my $scale = 0; $scale <= 1; ++$scale) {
                if ( $modulate || $blend || $scale ) {
                    output_copyfunc($src, $dst, $modulate, $blend, $scale);
                }
            }
        }
    }
}

open_file("SDL_blit_auto.h");
output_copydefs();
for (my $i = 0; $i <= $#src_formats; ++$i) {
    for (my $j = 0; $j <= $#dst_formats; ++$j) {
        output_copyfunc_h($src_formats[$i], $dst_formats[$j]);
    }
}
print FILE "\n";
close_file("SDL_blit_auto.h");

open_file("SDL_blit_auto.c");
output_copyinc();
for (my $i = 0; $i <= $#src_formats; ++$i) {
    for (my $j = 0; $j <= $#dst_formats; ++$j) {
        output_copyfunc_c($src_formats[$i], $dst_formats[$j]);
    }
}
output_copyfunctable();
close_file("SDL_blit_auto.c");