- /*
- * Mpeg Layer-1 audio decoder
- * --------------------------
- * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
- * near unoptimzed ...
- *
- * may have a few bugs after last optimization ...
- *
- */
-
- /* $Id: layer1.c,v 1.20 2004/04/14 22:15:44 robert Exp $ */
-
- #ifdef HAVE_CONFIG_H
- # include <config.h>
- #endif
-
- #ifdef USE_LAYER_1
-
- #include <assert.h>
- #include "common.h"
- #include "decode_i386.h"
-
- #ifdef WITH_DMALLOC
- #include <dmalloc.h>
- #endif
-
- static void
- I_step_one(PMPSTR mp, unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],struct frame *fr)
- {
- unsigned int *ba=balloc;
- unsigned int *sca = (unsigned int *) scale_index;
-
- assert ( fr->stereo == 1 || fr->stereo == 2 );
- if(fr->stereo==2) {
- int i;
- int jsbound = fr->jsbound;
- for (i=0;i<jsbound;i++) {
- *ba++ = getbits(mp,4);
- *ba++ = getbits(mp,4);
- }
- for (i=jsbound;i<SBLIMIT;i++)
- *ba++ = getbits(mp,4);
-
- ba = balloc;
-
- for (i=0;i<jsbound;i++) {
- if ((*ba++))
- *sca++ = getbits(mp,6);
- if ((*ba++))
- *sca++ = getbits(mp,6);
- }
- for (i=jsbound;i<SBLIMIT;i++)
- if ((*ba++)) {
- *sca++ = getbits(mp,6);
- *sca++ = getbits(mp,6);
- }
- }
- else {
- int i;
- for (i=0;i<SBLIMIT;i++)
- *ba++ = getbits(mp,4);
- ba = balloc;
- for (i=0;i<SBLIMIT;i++)
- if ((*ba++))
- *sca++ = getbits(mp,6);
- }
- }
-
- static void
- I_step_two(PMPSTR mp, real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT],
- unsigned int scale_index[2][SBLIMIT],struct frame *fr)
- {
- int i,n;
- int smpb[2*SBLIMIT]; /* values: 0-65535 */
- int *sample;
- unsigned int *ba;
- unsigned int *sca = (unsigned int *) scale_index;
-
- assert ( fr->stereo == 1 || fr->stereo == 2 );
- if(fr->stereo == 2) {
- int jsbound = fr->jsbound;
- real *f0 = fraction[0];
- real *f1 = fraction[1];
- ba = balloc;
- for (sample=smpb,i=0;i<jsbound;i++) {
- if ((n = *ba++))
- *sample++ = getbits(mp,n+1);
- if ((n = *ba++))
- *sample++ = getbits(mp,n+1);
- }
- for (i=jsbound;i<SBLIMIT;i++)
- if ((n = *ba++))
- *sample++ = getbits(mp,n+1);
-
- ba = balloc;
- for (sample=smpb,i=0;i<jsbound;i++) {
- if((n=*ba++))
- *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++];
- else
- *f0++ = 0.0;
- if((n=*ba++))
- *f1++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++];
- else
- *f1++ = 0.0;
- }
- for (i=jsbound;i<SBLIMIT;i++) {
- if ((n=*ba++)) {
- real samp = (real)( ((-1)<<n) + (*sample++) + 1);
- *f0++ = samp * muls[n+1][*sca++];
- *f1++ = samp * muls[n+1][*sca++];
- }
- else
- *f0++ = *f1++ = 0.0;
- }
- for(i=fr->down_sample_sblimit;i<32;i++)
- fraction[0][i] = fraction[1][i] = 0.0;
- }
- else {
- real *f0 = fraction[0];
- ba = balloc;
- for (sample=smpb,i=0;i<SBLIMIT;i++)
- if ((n = *ba++))
- *sample++ = getbits(mp,n+1);
- ba = balloc;
- for (sample=smpb,i=0;i<SBLIMIT;i++) {
- if((n=*ba++))
- *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++];
- else
- *f0++ = 0.0;
- }
- for(i=fr->down_sample_sblimit;i<32;i++)
- fraction[0][i] = 0.0;
- }
- }
-
- /*int do_layer1(struct frame *fr,int outmode,struct audio_info_struct *ai) */
- int do_layer1(PMPSTR mp, unsigned char *pcm_sample,int *pcm_point)
- {
- int clip=0;
- unsigned int balloc[2*SBLIMIT];
- unsigned int scale_index[2][SBLIMIT];
- real fraction[2][SBLIMIT];
- struct frame *fr=&(mp->fr);
- int i,stereo = fr->stereo;
- int single = fr->single;
-
- fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32;
-
- if (stereo == 1 || single == 3)
- single = 0;
-
- I_step_one(mp,balloc,scale_index,fr);
-
- for (i=0;i<SCALE_BLOCK;i++)
- {
- I_step_two(mp,fraction,balloc,scale_index,fr);
-
- if(single >= 0)
- {
- clip += synth_1to1_mono( mp, (real *) fraction[single],pcm_sample,pcm_point);
- }
- else {
- int p1 = *pcm_point;
- clip += synth_1to1( mp, (real *) fraction[0],0,pcm_sample,&p1);
- clip += synth_1to1( mp, (real *) fraction[1],1,pcm_sample,pcm_point);
- }
- }
-
- return clip;
- }
-
- #endif
-