#!/usr/bin/perl -w

use warnings;
use strict;

my @audiotypes = qw(
    U8
    S8
    U16LSB
    S16LSB
    U16MSB
    S16MSB
    S32LSB
    S32MSB
    F32LSB
    F32MSB
);

my %funcs;

my $custom_converters = 0;


sub outputHeader {
    print <<EOF;
/* DO NOT EDIT!  This file is generated by sdlgenaudiocvt.pl */
/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 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"
#include "SDL_audio.h"
#include "SDL_audio_c.h"

/* *INDENT-OFF* */

EOF

    my @vals = ( 127, 32767, 2147483647 );
    foreach (@vals) {
        my $val = $_;
        my $fval = 1.0 / $val;
        print("#define DIVBY${val} ${fval}f\n");
    }

    print("\n");
}

sub outputFooter {
    print <<EOF;
/* *INDENT-ON* */

/* vi: set ts=4 sw=4 expandtab: */
EOF
}

sub splittype {
    my $t = shift;
    my ($signed, $size, $endian) = $t =~ /([USF])(\d+)([LM]SB|)/;
    my $float = ($signed eq 'F') ? 1 : 0;
    $signed = (($float) or ($signed eq 'S')) ? 1 : 0;
    $endian = 'NONE' if ($endian eq '');

    my $ctype = '';
    if ($float) {
        $ctype = (($size == 32) ? 'float' : 'double');
    } else {
        $ctype = (($signed) ? 'S' : 'U') . "int${size}";
    }

    return ($signed, $float, $size, $endian, $ctype);
}

sub getSwapFunc {
    my ($size, $signed, $float, $endian, $val) = @_;
    my $BEorLE = (($endian eq 'MSB') ? 'BE' : 'LE');
    my $code = '';

    if ($float) {
        $code = "SDL_SwapFloat${BEorLE}($val)";
    } else {
        if ($size > 8) {
            $code = "SDL_Swap${BEorLE}${size}($val)";
        } else {
            $code = $val;
        }

        if (($signed) and (!$float)) {
            $code = "((Sint${size}) $code)";
        }
    }

    return "${code}";
}


sub maxIntVal {
    my $size = shift;
    if ($size == 8) {
        return 0x7F;
    } elsif ($size == 16) {
        return 0x7FFF;
    } elsif ($size == 32) {
        return 0x7FFFFFFF;
    }

    die("bug in script.\n");
}

sub getFloatToIntMult {
    my $size = shift;
    my $val = maxIntVal($size) . '.0';
    $val .= 'f' if ($size < 32);
    return $val;
}

sub getIntToFloatDivBy {
    my $size = shift;
    return 'DIVBY' . maxIntVal($size);
}

sub getSignFlipVal {
    my $size = shift;
    if ($size == 8) {
        return '0x80';
    } elsif ($size == 16) {
        return '0x8000';
    } elsif ($size == 32) {
        return '0x80000000';
    }

    die("bug in script.\n");
}

sub buildCvtFunc {
    my ($from, $to) = @_;
    my ($fsigned, $ffloat, $fsize, $fendian, $fctype) = splittype($from);
    my ($tsigned, $tfloat, $tsize, $tendian, $tctype) = splittype($to);
    my $diffs = 0;
    $diffs++ if ($fsize != $tsize);
    $diffs++ if ($fsigned != $tsigned);
    $diffs++ if ($ffloat != $tfloat);
    $diffs++ if ($fendian ne $tendian);

    return if ($diffs == 0);

    my $hashid = "$from/$to";
    if (1) { # !!! FIXME: if ($diffs > 1) {
        my $sym = "SDL_Convert_${from}_to_${to}";
        $funcs{$hashid} = $sym;
        $custom_converters++;

        # Always unsigned for ints, for possible byteswaps.
        my $srctype = (($ffloat) ? 'float' : "Uint${fsize}");

        print <<EOF;
static void SDLCALL
${sym}(SDL_AudioCVT * cvt, SDL_AudioFormat format)
{
    int i;
    const $srctype *src;
    $tctype *dst;

#ifdef DEBUG_CONVERT
    fprintf(stderr, "Converting AUDIO_${from} to AUDIO_${to}.\\n");
#endif

EOF

        if ($fsize < $tsize) {
            my $mult = $tsize / $fsize;
            print <<EOF;
    src = ((const $srctype *) (cvt->buf + cvt->len_cvt)) - 1;
    dst = (($tctype *) (cvt->buf + cvt->len_cvt * $mult)) - 1;
    for (i = cvt->len_cvt / sizeof ($srctype); i; --i, --src, --dst) {
EOF
        } else {
            print <<EOF;
    src = (const $srctype *) cvt->buf;
    dst = ($tctype *) cvt->buf;
    for (i = cvt->len_cvt / sizeof ($srctype); i; --i, ++src, ++dst) {
EOF
        }

        # Have to convert to/from float/int.
        # !!! FIXME: cast through double for int32<->float?
        my $code = getSwapFunc($fsize, $fsigned, $ffloat, $fendian, '*src');
        if ($ffloat != $tfloat) {
            if ($ffloat) {
                my $mult = getFloatToIntMult($tsize);
                if (!$tsigned) {   # bump from -1.0f/1.0f to 0.0f/2.0f
                    $code = "($code + 1.0f)";
                }
                $code = "(($tctype) ($code * $mult))";
            } else {
                # $divby will be the reciprocal, to avoid pipeline stalls
                #  from floating point division...so multiply it.
                my $divby = getIntToFloatDivBy($fsize);
                $code = "(((float) $code) * $divby)";
                if (!$fsigned) {   # bump from 0.0f/2.0f to -1.0f/1.0f.
                    $code = "($code - 1.0f)";
                }
            }
        } else {
            # All integer conversions here.
            if ($fsigned != $tsigned) {
                my $signflipval = getSignFlipVal($fsize);
                $code = "(($code) ^ $signflipval)";
            }

            my $shiftval = abs($fsize - $tsize);
            if ($fsize < $tsize) {
                $code = "((($tctype) $code) << $shiftval)";
            } elsif ($fsize > $tsize) {
                $code = "(($tctype) ($code >> $shiftval))";
            }
        }

        my $swap = getSwapFunc($tsize, $tsigned, $tfloat, $tendian, 'val');

        print <<EOF;
        const $tctype val = $code;
        *dst = ${swap};
    }

EOF

        if ($fsize > $tsize) {
            my $divby = $fsize / $tsize;
            print("    cvt->len_cvt /= $divby;\n");
        } elsif ($fsize < $tsize) {
            my $mult = $tsize / $fsize;
            print("    cvt->len_cvt *= $mult;\n");
        }

        print <<EOF;
    if (cvt->filters[++cvt->filter_index]) {
        cvt->filters[cvt->filter_index] (cvt, AUDIO_$to);
    }
}

EOF

    } else {
        if ($fsigned != $tsigned) {
            $funcs{$hashid} = 'SDL_ConvertSigned';
        } elsif ($ffloat != $tfloat) {
            $funcs{$hashid} = 'SDL_ConvertFloat';
        } elsif ($fsize != $tsize) {
            $funcs{$hashid} = 'SDL_ConvertSize';
        } elsif ($fendian ne $tendian) {
            $funcs{$hashid} = 'SDL_ConvertEndian';
        } else {
            die("error in script.\n");
        }
    }
}

outputHeader();

foreach (@audiotypes) {
    my $from = $_;
    foreach (@audiotypes) {
        my $to = $_;
        buildCvtFunc($from, $to);
    }
}

print <<EOF;
const SDL_AudioTypeFilters sdl_audio_type_filters[] =
{
EOF

foreach (@audiotypes) {
    my $from = $_;
    foreach (@audiotypes) {
        my $to = $_;
        if ($from ne $to) {
            my $hashid = "$from/$to";
            my $sym = $funcs{$hashid};
            print("    { AUDIO_$from, AUDIO_$to, $sym },\n");
        }
    }
}

print <<EOF;
};


EOF

outputFooter();

exit 0;

# end of sdlgenaudiocvt.pl ...

