/*  * 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>#endifstatic 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 voidI_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