src/audio/SDL_wave.c
author Sam Lantinga <slouken@libsdl.org>
Mon, 06 Feb 2006 08:28:51 +0000
changeset 1330 450721ad5436
parent 1312 c9b51268668f
child 1336 3692456e7b0f
permissions -rw-r--r--
It's now possible to build SDL without any C runtime at all on Windows,
using Visual C++ 2005
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/*
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    SDL - Simple DirectMedia Layer
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    Copyright (C) 1997-2006 Sam Lantinga
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    This library is free software; you can redistribute it and/or
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    modify it under the terms of the GNU Lesser General Public
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    License as published by the Free Software Foundation; either
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    version 2.1 of the License, or (at your option) any later version.
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    This library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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    Lesser General Public License for more details.
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    You should have received a copy of the GNU Lesser General Public
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    License along with this library; if not, write to the Free Software
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    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
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    Sam Lantinga
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    slouken@libsdl.org
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*/
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#ifndef DISABLE_FILE
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/* Microsoft WAVE file loading routines */
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#include "SDL_error.h"
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#include "SDL_audio.h"
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#include "SDL_stdlib.h"
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#include "SDL_string.h"
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#include "SDL_wave.h"
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#include "SDL_endian.h"
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static int ReadChunk(SDL_RWops *src, Chunk *chunk);
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struct MS_ADPCM_decodestate {
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	Uint8 hPredictor;
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	Uint16 iDelta;
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	Sint16 iSamp1;
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	Sint16 iSamp2;
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};
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static struct MS_ADPCM_decoder {
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	WaveFMT wavefmt;
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	Uint16 wSamplesPerBlock;
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	Uint16 wNumCoef;
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	Sint16 aCoeff[7][2];
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	/* * * */
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	struct MS_ADPCM_decodestate state[2];
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} MS_ADPCM_state;
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static int InitMS_ADPCM(WaveFMT *format)
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{
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	Uint8 *rogue_feel;
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	Uint16 extra_info;
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	int i;
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	/* Set the rogue pointer to the MS_ADPCM specific data */
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	MS_ADPCM_state.wavefmt.encoding = SDL_SwapLE16(format->encoding);
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	MS_ADPCM_state.wavefmt.channels = SDL_SwapLE16(format->channels);
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	MS_ADPCM_state.wavefmt.frequency = SDL_SwapLE32(format->frequency);
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	MS_ADPCM_state.wavefmt.byterate = SDL_SwapLE32(format->byterate);
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	MS_ADPCM_state.wavefmt.blockalign = SDL_SwapLE16(format->blockalign);
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	MS_ADPCM_state.wavefmt.bitspersample =
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					 SDL_SwapLE16(format->bitspersample);
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	rogue_feel = (Uint8 *)format+sizeof(*format);
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	if ( sizeof(*format) == 16 ) {
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		extra_info = ((rogue_feel[1]<<8)|rogue_feel[0]);
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		rogue_feel += sizeof(Uint16);
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	}
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	MS_ADPCM_state.wSamplesPerBlock = ((rogue_feel[1]<<8)|rogue_feel[0]);
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	rogue_feel += sizeof(Uint16);
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	MS_ADPCM_state.wNumCoef = ((rogue_feel[1]<<8)|rogue_feel[0]);
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	rogue_feel += sizeof(Uint16);
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	if ( MS_ADPCM_state.wNumCoef != 7 ) {
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		SDL_SetError("Unknown set of MS_ADPCM coefficients");
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		return(-1);
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	}
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	for ( i=0; i<MS_ADPCM_state.wNumCoef; ++i ) {
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		MS_ADPCM_state.aCoeff[i][0] = ((rogue_feel[1]<<8)|rogue_feel[0]);
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		rogue_feel += sizeof(Uint16);
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		MS_ADPCM_state.aCoeff[i][1] = ((rogue_feel[1]<<8)|rogue_feel[0]);
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		rogue_feel += sizeof(Uint16);
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	}
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	return(0);
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}
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static Sint32 MS_ADPCM_nibble(struct MS_ADPCM_decodestate *state,
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					Uint8 nybble, Sint16 *coeff)
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{
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	const Sint32 max_audioval = ((1<<(16-1))-1);
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	const Sint32 min_audioval = -(1<<(16-1));
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	const Sint32 adaptive[] = {
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		230, 230, 230, 230, 307, 409, 512, 614,
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		768, 614, 512, 409, 307, 230, 230, 230
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	};
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	Sint32 new_sample, delta;
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	new_sample = ((state->iSamp1 * coeff[0]) +
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		      (state->iSamp2 * coeff[1]))/256;
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	if ( nybble & 0x08 ) {
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		new_sample += state->iDelta * (nybble-0x10);
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	} else {
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		new_sample += state->iDelta * nybble;
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	}
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	if ( new_sample < min_audioval ) {
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		new_sample = min_audioval;
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	} else
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	if ( new_sample > max_audioval ) {
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		new_sample = max_audioval;
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	}
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	delta = ((Sint32)state->iDelta * adaptive[nybble])/256;
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	if ( delta < 16 ) {
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		delta = 16;
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	}
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	state->iDelta = delta;
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	state->iSamp2 = state->iSamp1;
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	state->iSamp1 = new_sample;
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	return(new_sample);
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}
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static int MS_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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{
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	struct MS_ADPCM_decodestate *state[2];
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	Uint8 *freeable, *encoded, *decoded;
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	Sint32 encoded_len, samplesleft;
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	Sint8 nybble, stereo;
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	Sint16 *coeff[2];
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	Sint32 new_sample;
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	/* Allocate the proper sized output buffer */
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	encoded_len = *audio_len;
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	encoded = *audio_buf;
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	freeable = *audio_buf;
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	*audio_len = (encoded_len/MS_ADPCM_state.wavefmt.blockalign) * 
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				MS_ADPCM_state.wSamplesPerBlock*
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				MS_ADPCM_state.wavefmt.channels*sizeof(Sint16);
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	*audio_buf = (Uint8 *)malloc(*audio_len);
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	if ( *audio_buf == NULL ) {
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		SDL_Error(SDL_ENOMEM);
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		return(-1);
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	}
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	decoded = *audio_buf;
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	/* Get ready... Go! */
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	stereo = (MS_ADPCM_state.wavefmt.channels == 2);
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	state[0] = &MS_ADPCM_state.state[0];
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	state[1] = &MS_ADPCM_state.state[stereo];
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	while ( encoded_len >= MS_ADPCM_state.wavefmt.blockalign ) {
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		/* Grab the initial information for this block */
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		state[0]->hPredictor = *encoded++;
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		if ( stereo ) {
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			state[1]->hPredictor = *encoded++;
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		}
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		state[0]->iDelta = ((encoded[1]<<8)|encoded[0]);
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		encoded += sizeof(Sint16);
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		if ( stereo ) {
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			state[1]->iDelta = ((encoded[1]<<8)|encoded[0]);
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			encoded += sizeof(Sint16);
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		}
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		state[0]->iSamp1 = ((encoded[1]<<8)|encoded[0]);
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		encoded += sizeof(Sint16);
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		if ( stereo ) {
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			state[1]->iSamp1 = ((encoded[1]<<8)|encoded[0]);
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			encoded += sizeof(Sint16);
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		}
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		state[0]->iSamp2 = ((encoded[1]<<8)|encoded[0]);
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		encoded += sizeof(Sint16);
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		if ( stereo ) {
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			state[1]->iSamp2 = ((encoded[1]<<8)|encoded[0]);
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			encoded += sizeof(Sint16);
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		}
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		coeff[0] = MS_ADPCM_state.aCoeff[state[0]->hPredictor];
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		coeff[1] = MS_ADPCM_state.aCoeff[state[1]->hPredictor];
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		/* Store the two initial samples we start with */
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		decoded[0] = state[0]->iSamp2&0xFF;
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		decoded[1] = state[0]->iSamp2>>8;
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		decoded += 2;
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		if ( stereo ) {
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			decoded[0] = state[1]->iSamp2&0xFF;
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			decoded[1] = state[1]->iSamp2>>8;
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			decoded += 2;
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		}
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		decoded[0] = state[0]->iSamp1&0xFF;
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		decoded[1] = state[0]->iSamp1>>8;
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		decoded += 2;
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		if ( stereo ) {
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			decoded[0] = state[1]->iSamp1&0xFF;
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			decoded[1] = state[1]->iSamp1>>8;
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			decoded += 2;
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		}
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		/* Decode and store the other samples in this block */
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		samplesleft = (MS_ADPCM_state.wSamplesPerBlock-2)*
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					MS_ADPCM_state.wavefmt.channels;
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		while ( samplesleft > 0 ) {
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			nybble = (*encoded)>>4;
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			new_sample = MS_ADPCM_nibble(state[0],nybble,coeff[0]);
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			decoded[0] = new_sample&0xFF;
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			new_sample >>= 8;
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			decoded[1] = new_sample&0xFF;
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			decoded += 2;
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			nybble = (*encoded)&0x0F;
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			new_sample = MS_ADPCM_nibble(state[1],nybble,coeff[1]);
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			decoded[0] = new_sample&0xFF;
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			new_sample >>= 8;
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			decoded[1] = new_sample&0xFF;
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			decoded += 2;
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			++encoded;
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			samplesleft -= 2;
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		}
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		encoded_len -= MS_ADPCM_state.wavefmt.blockalign;
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	}
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	free(freeable);
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	return(0);
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}
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struct IMA_ADPCM_decodestate {
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	Sint32 sample;
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	Sint8 index;
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};
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static struct IMA_ADPCM_decoder {
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	WaveFMT wavefmt;
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	Uint16 wSamplesPerBlock;
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	/* * * */
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	struct IMA_ADPCM_decodestate state[2];
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} IMA_ADPCM_state;
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static int InitIMA_ADPCM(WaveFMT *format)
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{
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	Uint8 *rogue_feel;
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	Uint16 extra_info;
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	/* Set the rogue pointer to the IMA_ADPCM specific data */
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	IMA_ADPCM_state.wavefmt.encoding = SDL_SwapLE16(format->encoding);
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	IMA_ADPCM_state.wavefmt.channels = SDL_SwapLE16(format->channels);
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	IMA_ADPCM_state.wavefmt.frequency = SDL_SwapLE32(format->frequency);
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	IMA_ADPCM_state.wavefmt.byterate = SDL_SwapLE32(format->byterate);
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	IMA_ADPCM_state.wavefmt.blockalign = SDL_SwapLE16(format->blockalign);
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	IMA_ADPCM_state.wavefmt.bitspersample =
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					 SDL_SwapLE16(format->bitspersample);
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	rogue_feel = (Uint8 *)format+sizeof(*format);
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	if ( sizeof(*format) == 16 ) {
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		extra_info = ((rogue_feel[1]<<8)|rogue_feel[0]);
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		rogue_feel += sizeof(Uint16);
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	}
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	IMA_ADPCM_state.wSamplesPerBlock = ((rogue_feel[1]<<8)|rogue_feel[0]);
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	return(0);
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}
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static Sint32 IMA_ADPCM_nibble(struct IMA_ADPCM_decodestate *state,Uint8 nybble)
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{
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	const Sint32 max_audioval = ((1<<(16-1))-1);
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	const Sint32 min_audioval = -(1<<(16-1));
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	const int index_table[16] = {
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		-1, -1, -1, -1,
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		 2,  4,  6,  8,
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		-1, -1, -1, -1,
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		 2,  4,  6,  8
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	};
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	const Sint32 step_table[89] = {
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		7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31,
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		34, 37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130,
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		143, 157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408,
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		449, 494, 544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282,
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		1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327,
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		3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630,
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		9493, 10442, 11487, 12635, 13899, 15289, 16818, 18500, 20350,
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		22385, 24623, 27086, 29794, 32767
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	};
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	Sint32 delta, step;
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	/* Compute difference and new sample value */
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	step = step_table[state->index];
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	delta = step >> 3;
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	if ( nybble & 0x04 ) delta += step;
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	if ( nybble & 0x02 ) delta += (step >> 1);
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	if ( nybble & 0x01 ) delta += (step >> 2);
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	if ( nybble & 0x08 ) delta = -delta;
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	state->sample += delta;
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	/* Update index value */
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	state->index += index_table[nybble];
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	if ( state->index > 88 ) {
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		state->index = 88;
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	} else
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	if ( state->index < 0 ) {
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		state->index = 0;
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	}
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	/* Clamp output sample */
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	if ( state->sample > max_audioval ) {
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		state->sample = max_audioval;
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	} else
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	if ( state->sample < min_audioval ) {
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		state->sample = min_audioval;
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	}
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	return(state->sample);
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}
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/* Fill the decode buffer with a channel block of data (8 samples) */
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static void Fill_IMA_ADPCM_block(Uint8 *decoded, Uint8 *encoded,
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	int channel, int numchannels, struct IMA_ADPCM_decodestate *state)
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{
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	int i;
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	Sint8 nybble;
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	Sint32 new_sample;
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	decoded += (channel * 2);
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	for ( i=0; i<4; ++i ) {
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		nybble = (*encoded)&0x0F;
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		new_sample = IMA_ADPCM_nibble(state, nybble);
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		decoded[0] = new_sample&0xFF;
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		new_sample >>= 8;
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		decoded[1] = new_sample&0xFF;
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		decoded += 2 * numchannels;
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		nybble = (*encoded)>>4;
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		new_sample = IMA_ADPCM_nibble(state, nybble);
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		decoded[0] = new_sample&0xFF;
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		new_sample >>= 8;
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		decoded[1] = new_sample&0xFF;
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		decoded += 2 * numchannels;
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		++encoded;
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	}
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}
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static int IMA_ADPCM_decode(Uint8 **audio_buf, Uint32 *audio_len)
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{
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	struct IMA_ADPCM_decodestate *state;
slouken@0
   335
	Uint8 *freeable, *encoded, *decoded;
slouken@0
   336
	Sint32 encoded_len, samplesleft;
slouken@0
   337
	int c, channels;
slouken@0
   338
slouken@0
   339
	/* Check to make sure we have enough variables in the state array */
slouken@0
   340
	channels = IMA_ADPCM_state.wavefmt.channels;
slouken@1330
   341
	if ( channels > SDL_arraysize(IMA_ADPCM_state.state) ) {
slouken@0
   342
		SDL_SetError("IMA ADPCM decoder can only handle %d channels",
slouken@1330
   343
					SDL_arraysize(IMA_ADPCM_state.state));
slouken@0
   344
		return(-1);
slouken@0
   345
	}
slouken@0
   346
	state = IMA_ADPCM_state.state;
slouken@0
   347
slouken@0
   348
	/* Allocate the proper sized output buffer */
slouken@0
   349
	encoded_len = *audio_len;
slouken@0
   350
	encoded = *audio_buf;
slouken@0
   351
	freeable = *audio_buf;
slouken@0
   352
	*audio_len = (encoded_len/IMA_ADPCM_state.wavefmt.blockalign) * 
slouken@0
   353
				IMA_ADPCM_state.wSamplesPerBlock*
slouken@0
   354
				IMA_ADPCM_state.wavefmt.channels*sizeof(Sint16);
slouken@0
   355
	*audio_buf = (Uint8 *)malloc(*audio_len);
slouken@0
   356
	if ( *audio_buf == NULL ) {
slouken@0
   357
		SDL_Error(SDL_ENOMEM);
slouken@0
   358
		return(-1);
slouken@0
   359
	}
slouken@0
   360
	decoded = *audio_buf;
slouken@0
   361
slouken@0
   362
	/* Get ready... Go! */
slouken@0
   363
	while ( encoded_len >= IMA_ADPCM_state.wavefmt.blockalign ) {
slouken@0
   364
		/* Grab the initial information for this block */
slouken@0
   365
		for ( c=0; c<channels; ++c ) {
slouken@0
   366
			/* Fill the state information for this block */
slouken@0
   367
			state[c].sample = ((encoded[1]<<8)|encoded[0]);
slouken@0
   368
			encoded += 2;
slouken@0
   369
			if ( state[c].sample & 0x8000 ) {
slouken@0
   370
				state[c].sample -= 0x10000;
slouken@0
   371
			}
slouken@0
   372
			state[c].index = *encoded++;
slouken@0
   373
			/* Reserved byte in buffer header, should be 0 */
slouken@0
   374
			if ( *encoded++ != 0 ) {
slouken@0
   375
				/* Uh oh, corrupt data?  Buggy code? */;
slouken@0
   376
			}
slouken@0
   377
slouken@0
   378
			/* Store the initial sample we start with */
slouken@0
   379
			decoded[0] = state[c].sample&0xFF;
slouken@0
   380
			decoded[1] = state[c].sample>>8;
slouken@0
   381
			decoded += 2;
slouken@0
   382
		}
slouken@0
   383
slouken@0
   384
		/* Decode and store the other samples in this block */
slouken@0
   385
		samplesleft = (IMA_ADPCM_state.wSamplesPerBlock-1)*channels;
slouken@0
   386
		while ( samplesleft > 0 ) {
slouken@0
   387
			for ( c=0; c<channels; ++c ) {
slouken@0
   388
				Fill_IMA_ADPCM_block(decoded, encoded,
slouken@0
   389
						c, channels, &state[c]);
slouken@0
   390
				encoded += 4;
slouken@0
   391
				samplesleft -= 8;
slouken@0
   392
			}
slouken@0
   393
			decoded += (channels * 8 * 2);
slouken@0
   394
		}
slouken@0
   395
		encoded_len -= IMA_ADPCM_state.wavefmt.blockalign;
slouken@0
   396
	}
slouken@0
   397
	free(freeable);
slouken@0
   398
	return(0);
slouken@0
   399
}
slouken@0
   400
slouken@0
   401
SDL_AudioSpec * SDL_LoadWAV_RW (SDL_RWops *src, int freesrc,
slouken@0
   402
		SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)
slouken@0
   403
{
slouken@0
   404
	int was_error;
slouken@0
   405
	Chunk chunk;
slouken@0
   406
	int lenread;
slouken@0
   407
	int MS_ADPCM_encoded, IMA_ADPCM_encoded;
slouken@0
   408
	int samplesize;
slouken@0
   409
slouken@0
   410
	/* WAV magic header */
slouken@0
   411
	Uint32 RIFFchunk;
slouken@1260
   412
	Uint32 wavelen = 0;
slouken@0
   413
	Uint32 WAVEmagic;
slouken@1260
   414
	Uint32 headerDiff = 0;
slouken@0
   415
slouken@0
   416
	/* FMT chunk */
slouken@0
   417
	WaveFMT *format = NULL;
slouken@0
   418
slouken@0
   419
	/* Make sure we are passed a valid data source */
slouken@0
   420
	was_error = 0;
slouken@0
   421
	if ( src == NULL ) {
slouken@0
   422
		was_error = 1;
slouken@0
   423
		goto done;
slouken@0
   424
	}
slouken@0
   425
		
slouken@0
   426
	/* Check the magic header */
slouken@0
   427
	RIFFchunk	= SDL_ReadLE32(src);
slouken@0
   428
	wavelen		= SDL_ReadLE32(src);
slouken@171
   429
	if ( wavelen == WAVE ) { /* The RIFFchunk has already been read */
slouken@171
   430
		WAVEmagic = wavelen;
slouken@171
   431
		wavelen   = RIFFchunk;
slouken@171
   432
		RIFFchunk = RIFF;
slouken@171
   433
	} else {
slouken@171
   434
		WAVEmagic = SDL_ReadLE32(src);
slouken@171
   435
	}
slouken@0
   436
	if ( (RIFFchunk != RIFF) || (WAVEmagic != WAVE) ) {
slouken@0
   437
		SDL_SetError("Unrecognized file type (not WAVE)");
slouken@0
   438
		was_error = 1;
slouken@0
   439
		goto done;
slouken@0
   440
	}
slouken@1260
   441
	headerDiff += sizeof(Uint32); // for WAVE
slouken@0
   442
slouken@0
   443
	/* Read the audio data format chunk */
slouken@0
   444
	chunk.data = NULL;
slouken@0
   445
	do {
slouken@0
   446
		if ( chunk.data != NULL ) {
slouken@0
   447
			free(chunk.data);
slouken@0
   448
		}
slouken@0
   449
		lenread = ReadChunk(src, &chunk);
slouken@0
   450
		if ( lenread < 0 ) {
slouken@0
   451
			was_error = 1;
slouken@0
   452
			goto done;
slouken@0
   453
		}
slouken@1260
   454
		// 2 Uint32's for chunk header+len, plus the lenread
slouken@1260
   455
		headerDiff += lenread + 2 * sizeof(Uint32);
slouken@0
   456
	} while ( (chunk.magic == FACT) || (chunk.magic == LIST) );
slouken@0
   457
slouken@0
   458
	/* Decode the audio data format */
slouken@0
   459
	format = (WaveFMT *)chunk.data;
slouken@0
   460
	if ( chunk.magic != FMT ) {
slouken@0
   461
		SDL_SetError("Complex WAVE files not supported");
slouken@0
   462
		was_error = 1;
slouken@0
   463
		goto done;
slouken@0
   464
	}
slouken@0
   465
	MS_ADPCM_encoded = IMA_ADPCM_encoded = 0;
slouken@0
   466
	switch (SDL_SwapLE16(format->encoding)) {
slouken@0
   467
		case PCM_CODE:
slouken@0
   468
			/* We can understand this */
slouken@0
   469
			break;
slouken@0
   470
		case MS_ADPCM_CODE:
slouken@0
   471
			/* Try to understand this */
slouken@0
   472
			if ( InitMS_ADPCM(format) < 0 ) {
slouken@0
   473
				was_error = 1;
slouken@0
   474
				goto done;
slouken@0
   475
			}
slouken@0
   476
			MS_ADPCM_encoded = 1;
slouken@0
   477
			break;
slouken@0
   478
		case IMA_ADPCM_CODE:
slouken@0
   479
			/* Try to understand this */
slouken@0
   480
			if ( InitIMA_ADPCM(format) < 0 ) {
slouken@0
   481
				was_error = 1;
slouken@0
   482
				goto done;
slouken@0
   483
			}
slouken@0
   484
			IMA_ADPCM_encoded = 1;
slouken@0
   485
			break;
slouken@0
   486
		default:
slouken@0
   487
			SDL_SetError("Unknown WAVE data format: 0x%.4x",
slouken@0
   488
					SDL_SwapLE16(format->encoding));
slouken@0
   489
			was_error = 1;
slouken@0
   490
			goto done;
slouken@0
   491
	}
slouken@0
   492
	memset(spec, 0, (sizeof *spec));
slouken@0
   493
	spec->freq = SDL_SwapLE32(format->frequency);
slouken@0
   494
	switch (SDL_SwapLE16(format->bitspersample)) {
slouken@0
   495
		case 4:
slouken@0
   496
			if ( MS_ADPCM_encoded || IMA_ADPCM_encoded ) {
slouken@0
   497
				spec->format = AUDIO_S16;
slouken@0
   498
			} else {
slouken@0
   499
				was_error = 1;
slouken@0
   500
			}
slouken@0
   501
			break;
slouken@0
   502
		case 8:
slouken@0
   503
			spec->format = AUDIO_U8;
slouken@0
   504
			break;
slouken@0
   505
		case 16:
slouken@0
   506
			spec->format = AUDIO_S16;
slouken@0
   507
			break;
slouken@0
   508
		default:
slouken@0
   509
			was_error = 1;
slouken@0
   510
			break;
slouken@0
   511
	}
slouken@0
   512
	if ( was_error ) {
slouken@0
   513
		SDL_SetError("Unknown %d-bit PCM data format",
slouken@0
   514
			SDL_SwapLE16(format->bitspersample));
slouken@0
   515
		goto done;
slouken@0
   516
	}
slouken@0
   517
	spec->channels = (Uint8)SDL_SwapLE16(format->channels);
slouken@0
   518
	spec->samples = 4096;		/* Good default buffer size */
slouken@0
   519
slouken@0
   520
	/* Read the audio data chunk */
slouken@0
   521
	*audio_buf = NULL;
slouken@0
   522
	do {
slouken@0
   523
		if ( *audio_buf != NULL ) {
slouken@0
   524
			free(*audio_buf);
slouken@0
   525
		}
slouken@0
   526
		lenread = ReadChunk(src, &chunk);
slouken@0
   527
		if ( lenread < 0 ) {
slouken@0
   528
			was_error = 1;
slouken@0
   529
			goto done;
slouken@0
   530
		}
slouken@0
   531
		*audio_len = lenread;
slouken@0
   532
		*audio_buf = chunk.data;
slouken@1260
   533
		if(chunk.magic != DATA) headerDiff += lenread + 2 * sizeof(Uint32);
slouken@0
   534
	} while ( chunk.magic != DATA );
slouken@1260
   535
	headerDiff += 2 * sizeof(Uint32); // for the data chunk and len
slouken@0
   536
slouken@0
   537
	if ( MS_ADPCM_encoded ) {
slouken@0
   538
		if ( MS_ADPCM_decode(audio_buf, audio_len) < 0 ) {
slouken@0
   539
			was_error = 1;
slouken@0
   540
			goto done;
slouken@0
   541
		}
slouken@0
   542
	}
slouken@0
   543
	if ( IMA_ADPCM_encoded ) {
slouken@0
   544
		if ( IMA_ADPCM_decode(audio_buf, audio_len) < 0 ) {
slouken@0
   545
			was_error = 1;
slouken@0
   546
			goto done;
slouken@0
   547
		}
slouken@0
   548
	}
slouken@0
   549
slouken@0
   550
	/* Don't return a buffer that isn't a multiple of samplesize */
slouken@0
   551
	samplesize = ((spec->format & 0xFF)/8)*spec->channels;
slouken@0
   552
	*audio_len &= ~(samplesize-1);
slouken@0
   553
slouken@0
   554
done:
slouken@0
   555
	if ( format != NULL ) {
slouken@0
   556
		free(format);
slouken@0
   557
	}
slouken@0
   558
	if ( freesrc && src ) {
slouken@0
   559
		SDL_RWclose(src);
slouken@0
   560
	}
slouken@1260
   561
	else {
slouken@1260
   562
		// seek to the end of the file (given by the RIFF chunk)
slouken@1330
   563
		SDL_RWseek(src, wavelen - chunk.length - headerDiff, RW_SEEK_CUR);
slouken@1260
   564
	}
slouken@0
   565
	if ( was_error ) {
slouken@0
   566
		spec = NULL;
slouken@0
   567
	}
slouken@0
   568
	return(spec);
slouken@0
   569
}
slouken@0
   570
slouken@0
   571
/* Since the WAV memory is allocated in the shared library, it must also
slouken@0
   572
   be freed here.  (Necessary under Win32, VC++)
slouken@0
   573
 */
slouken@0
   574
void SDL_FreeWAV(Uint8 *audio_buf)
slouken@0
   575
{
slouken@0
   576
	if ( audio_buf != NULL ) {
slouken@0
   577
		free(audio_buf);
slouken@0
   578
	}
slouken@0
   579
}
slouken@0
   580
slouken@0
   581
static int ReadChunk(SDL_RWops *src, Chunk *chunk)
slouken@0
   582
{
slouken@0
   583
	chunk->magic	= SDL_ReadLE32(src);
slouken@0
   584
	chunk->length	= SDL_ReadLE32(src);
slouken@0
   585
	chunk->data = (Uint8 *)malloc(chunk->length);
slouken@0
   586
	if ( chunk->data == NULL ) {
slouken@0
   587
		SDL_Error(SDL_ENOMEM);
slouken@0
   588
		return(-1);
slouken@0
   589
	}
slouken@0
   590
	if ( SDL_RWread(src, chunk->data, chunk->length, 1) != 1 ) {
slouken@0
   591
		SDL_Error(SDL_EFREAD);
slouken@0
   592
		free(chunk->data);
slouken@0
   593
		return(-1);
slouken@0
   594
	}
slouken@0
   595
	return(chunk->length);
slouken@0
   596
}
slouken@0
   597
slouken@0
   598
#endif /* ENABLE_FILE */