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/*
libdemac - A Monkey's Audio decoder
$Id: decoder.c 19552 2008-12-21 23:49:02Z amiconn $
Copyright (C) Dave Chapman 2007
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
*/
#include <inttypes.h>
#include <string.h>
#include "demac.h"
#include "predictor.h"
#include "entropy.h"
#include "filter.h"
#include "demac_config.h"
/* Statically allocate the filter buffers */
static filter_int filterbuf32[(32*3 + FILTER_HISTORY_SIZE) * 2]
IBSS_ATTR __attribute__((aligned(16))); /* 2432/4864 bytes */
static filter_int filterbuf256[(256*3 + FILTER_HISTORY_SIZE) * 2]
IBSS_ATTR __attribute__((aligned(16))); /* 5120/10240 bytes */
/* This is only needed for "insane" files, and no current Rockbox targets
can hope to decode them in realtime, although the Gigabeat S comes close. */
static filter_int filterbuf1280[(1280*3 + FILTER_HISTORY_SIZE) * 2]
IBSS_ATTR_DEMAC_INSANEBUF __attribute__((aligned(16)));
/* 17408 or 34816 bytes */
void init_frame_decoder(struct ape_ctx_t* ape_ctx,
unsigned char* inbuffer, int* firstbyte,
int* bytesconsumed)
{
init_entropy_decoder(ape_ctx, inbuffer, firstbyte, bytesconsumed);
//printf("CRC=0x%08x\n",ape_ctx->CRC);
//printf("Flags=0x%08x\n",ape_ctx->frameflags);
init_predictor_decoder(&ape_ctx->predictor);
switch (ape_ctx->compressiontype)
{
case 2000:
init_filter_16_11(filterbuf32);
break;
case 3000:
init_filter_64_11(filterbuf256);
break;
case 4000:
init_filter_256_13(filterbuf256);
init_filter_32_10(filterbuf32);
break;
case 5000:
init_filter_1280_15(filterbuf1280);
init_filter_256_13(filterbuf256);
init_filter_16_11(filterbuf32);
}
}
int ICODE_ATTR_DEMAC decode_chunk(struct ape_ctx_t* ape_ctx,
unsigned char* inbuffer, int* firstbyte,
int* bytesconsumed,
int32_t* decoded0, int32_t* decoded1,
int count)
{
int32_t left, right;
#ifdef ROCKBOX
int scale = (APE_OUTPUT_DEPTH - ape_ctx->bps);
#define SCALE(x) ((x) << scale)
#else
#define SCALE(x) (x)
#endif
if ((ape_ctx->channels==1) || ((ape_ctx->frameflags
& (APE_FRAMECODE_PSEUDO_STEREO|APE_FRAMECODE_STEREO_SILENCE))
== APE_FRAMECODE_PSEUDO_STEREO)) {
entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed,
decoded0, NULL, count);
if (ape_ctx->frameflags & APE_FRAMECODE_MONO_SILENCE) {
/* We are pure silence, so we're done. */
return 0;
}
switch (ape_ctx->compressiontype)
{
case 2000:
apply_filter_16_11(ape_ctx->fileversion,decoded0,NULL,count);
break;
case 3000:
apply_filter_64_11(ape_ctx->fileversion,decoded0,NULL,count);
break;
case 4000:
apply_filter_32_10(ape_ctx->fileversion,decoded0,NULL,count);
apply_filter_256_13(ape_ctx->fileversion,decoded0,NULL,count);
break;
case 5000:
apply_filter_16_11(ape_ctx->fileversion,decoded0,NULL,count);
apply_filter_256_13(ape_ctx->fileversion,decoded0,NULL,count);
apply_filter_1280_15(ape_ctx->fileversion,decoded0,NULL,count);
}
/* Now apply the predictor decoding */
predictor_decode_mono(&ape_ctx->predictor,decoded0,count);
if (ape_ctx->channels==2) {
/* Pseudo-stereo - copy left channel to right channel */
while (count--)
{
left = *decoded0;
*(decoded1++) = *(decoded0++) = SCALE(left);
}
}
#ifdef ROCKBOX
else {
/* Scale to output depth */
while (count--)
{
left = *decoded0;
*(decoded0++) = SCALE(left);
}
}
#endif
} else { /* Stereo */
entropy_decode(ape_ctx, inbuffer, firstbyte, bytesconsumed,
decoded0, decoded1, count);
if ((ape_ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE)
== APE_FRAMECODE_STEREO_SILENCE) {
/* We are pure silence, so we're done. */
return 0;
}
/* Apply filters - compression type 1000 doesn't have any */
switch (ape_ctx->compressiontype)
{
case 2000:
apply_filter_16_11(ape_ctx->fileversion,decoded0,decoded1,count);
break;
case 3000:
apply_filter_64_11(ape_ctx->fileversion,decoded0,decoded1,count);
break;
case 4000:
apply_filter_32_10(ape_ctx->fileversion,decoded0,decoded1,count);
apply_filter_256_13(ape_ctx->fileversion,decoded0,decoded1,count);
break;
case 5000:
apply_filter_16_11(ape_ctx->fileversion,decoded0,decoded1,count);
apply_filter_256_13(ape_ctx->fileversion,decoded0,decoded1,count);
apply_filter_1280_15(ape_ctx->fileversion,decoded0,decoded1,count);
}
/* Now apply the predictor decoding */
predictor_decode_stereo(&ape_ctx->predictor,decoded0,decoded1,count);
/* Decorrelate and scale to output depth */
while (count--)
{
left = *decoded1 - (*decoded0 / 2);
right = left + *decoded0;
*(decoded0++) = SCALE(left);
*(decoded1++) = SCALE(right);
}
}
return 0;
}
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