/*

SDL_mixer: An audio mixer library based on the SDL library

Copyright (C) 1997-2001 Sam Lantinga

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Library General Public

License as published by the Free Software Foundation; either

version 2 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

Library General Public License for more details.

You should have received a copy of the GNU Library General Public

License along with this library; if not, write to the Free

Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

This is the source needed to decode an AIFF file into a waveform.

It's pretty straightforward once you get going. The only

externally-callable function is Mix_LoadAIFF_RW(), which is meant to

act as identically to SDL_LoadWAV_RW() as possible.

This file by Torbjörn Andersson (torbjorn.andersson@eurotime.se)

*/

#include <string.h>

#include "SDL_mixer.h"

#include "load_aiff.h"

/*********************************************/

/* Define values for AIFF (IFF audio) format */

/*********************************************/

#define FORM 0x4d524f46 /* "FORM" */

#define AIFF 0x46464941 /* "AIFF" */

#define SSND 0x444e5353 /* "SSND" */

#define COMM 0x4d4d4f43 /* "COMM" */

/* This function was taken from libsndfile. I don't pretend to fully

* understand it.

*/

static Uint32 SANE_to_Uint32 (Uint8 *sanebuf)

{

/* Is the frequency outside of what we can represent with Uint32? */

if ( (sanebuf[0] & 0x80) || (sanebuf[0] <= 0x3F) || (sanebuf[0] > 0x40)

|| (sanebuf[0] == 0x40 && sanebuf[1] > 0x1C) )

return 0;

return ((sanebuf[2] << 23) | (sanebuf[3] << 15) | (sanebuf[4] << 7)

| (sanebuf[5] >> 1)) >> (29 - sanebuf[1]);

}

/* This function is based on SDL_LoadWAV_RW(). */

SDL_AudioSpec *Mix_LoadAIFF_RW (SDL_RWops *src, int freesrc,

SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)

{

int was_error;

int found_SSND;

int found_COMM;

long start;

Uint32 chunk_type;

Uint32 chunk_length;

long next_chunk;

/* AIFF magic header */

Uint32 FORMchunk;

Uint32 AIFFmagic;

/* SSND chunk */

Uint32 offset;

Uint32 blocksize;

/* COMM format chunk */

Uint16 channels;

Uint32 numsamples;

Uint16 samplesize;

Uint8 sane_freq[10];

Uint32 frequency;

/* Make sure we are passed a valid data source */

was_error = 0;

if ( src == NULL ) {

was_error = 1;

goto done;

}

FORMchunk = SDL_ReadLE32(src);

chunk_length = SDL_ReadBE32(src);

if ( chunk_length == AIFF ) { /* The FORMchunk has already been read */

AIFFmagic = chunk_length;

chunk_length = FORMchunk;

FORMchunk = FORM;

} else {

AIFFmagic = SDL_ReadLE32(src);

}

if ( (FORMchunk != FORM) || (AIFFmagic != AIFF) ) {

SDL_SetError("Unrecognized file type (not AIFF)");

was_error = 1;

goto done;

}

/* TODO: Better santity-checking. */

found_SSND = 0;

found_COMM = 0;

do {

chunk_type = SDL_ReadLE32(src);

chunk_length = SDL_ReadBE32(src);

next_chunk = SDL_RWtell(src) + chunk_length;

/* Paranoia to avoid infinite loops */

if (chunk_length == 0)

break;

switch (chunk_type) {

case SSND:

found_SSND = 1;

offset = SDL_ReadBE32(src);

blocksize = SDL_ReadBE32(src);

start = SDL_RWtell(src) + offset;

break;

case COMM:

found_COMM = 1;

channels = SDL_ReadBE16(src);

numsamples = SDL_ReadBE32(src);

samplesize = SDL_ReadBE16(src);

SDL_RWread(src, sane_freq, sizeof(sane_freq), 1);

frequency = SANE_to_Uint32(sane_freq);

if (frequency == 0) {

SDL_SetError("Bad AIFF sample frequency");

was_error = 1;

goto done;

}

break;

default:

break;

}

} while ( ( !found_SSND || !found_COMM )

&& SDL_RWseek(src, next_chunk, SEEK_SET) != 1 );

if ( !found_SSND ) {

SDL_SetError("Bad AIFF (no SSND chunk)");

was_error = 1;

goto done;

}

if ( !found_COMM ) {

SDL_SetError("Bad AIFF (no COMM chunk)");

was_error = 1;

goto done;

}

/* Decode the audio data format */

memset(spec, 0, sizeof(*spec));

spec->freq = frequency;

switch (samplesize) {

case 8:

spec->format = AUDIO_S8;

break;

case 16:

spec->format = AUDIO_S16MSB;

break;

default:

SDL_SetError("Unsupported AIFF samplesize");

was_error = 1;

goto done;

}

spec->channels = (Uint8) channels;

spec->samples = 4096; /* Good default buffer size */

*audio_len = channels * numsamples * (samplesize / 8);

*audio_buf = (Uint8 *)malloc(*audio_len);

if ( *audio_buf == NULL ) {

SDL_SetError("Out of memory");

return(NULL);

}

SDL_RWseek(src, start, SEEK_SET);

if ( SDL_RWread(src, *audio_buf, *audio_len, 1) != 1 ) {

SDL_SetError("Unable to read audio data");

return(NULL);

}

/* Don't return a buffer that isn't a multiple of samplesize */

*audio_len &= ~((samplesize / 8) - 1);

done:

if ( freesrc && src ) {

SDL_RWclose(src);

}

if ( was_error ) {

spec = NULL;

}

return(spec);

}