kolibrios/programs/media/ac97snd/trunk/mpg/layer1.c
Sergey Semyonov (Serge) 86db9e1fc4 updated ac97snd
git-svn-id: svn://kolibrios.org@228 a494cfbc-eb01-0410-851d-a64ba20cac60
2006-12-02 08:47:11 +00:00

152 lines
3.7 KiB
C

/*
layer1.c: the layer 1 decoder
copyright 1995-2006 by the mpg123 project - free software under the terms of the LGPL 2.1
see COPYING and AUTHORS files in distribution or http://mpg123.de
initially written by Michael Hipp
may have a few bugs after last optimization ...
*/
#include "mpg123.h"
void I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],struct frame *fr)
{
unsigned int *ba=balloc;
unsigned int *sca = (unsigned int *) scale_index;
if(fr->stereo == 2) {
int i;
int jsbound = fr->jsbound;
for (i=0;i<jsbound;i++) {
*ba++ = getbits(4);
*ba++ = getbits(4);
}
for (i=jsbound;i<SBLIMIT;i++)
*ba++ = getbits(4);
ba = balloc;
for (i=0;i<jsbound;i++) {
if ((*ba++))
*sca++ = getbits(6);
if ((*ba++))
*sca++ = getbits(6);
}
for (i=jsbound;i<SBLIMIT;i++)
if ((*ba++)) {
*sca++ = getbits(6);
*sca++ = getbits(6);
}
}
else {
int i;
for (i=0;i<SBLIMIT;i++)
*ba++ = getbits(4);
ba = balloc;
for (i=0;i<SBLIMIT;i++)
if ((*ba++))
*sca++ = getbits(6);
}
}
void I_step_two(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;
register unsigned int *ba;
register unsigned int *sca = (unsigned int *) scale_index;
if(fr->stereo == 2) {
int jsbound = fr->jsbound;
register real *f0 = fraction[0];
register real *f1 = fraction[1];
ba = balloc;
for (sample=smpb,i=0;i<jsbound;i++) {
if ((n = *ba++))
*sample++ = getbits(n+1);
if ((n = *ba++))
*sample++ = getbits(n+1);
}
for (i=jsbound;i<SBLIMIT;i++)
if ((n = *ba++))
*sample++ = getbits(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 = ( ((-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 {
register real *f0 = fraction[0];
ba = balloc;
for (sample=smpb,i=0;i<SBLIMIT;i++)
if ((n = *ba++))
*sample++ = getbits(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,byte *pcm_sample, int *pcm_point)
{
int clip=0;
int i,stereo = fr->stereo;
unsigned int balloc[2*SBLIMIT];
unsigned int scale_index[2][SBLIMIT];
real fraction[2][SBLIMIT];
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(balloc,scale_index,fr);
for (i=0;i<SCALE_BLOCK;i++)
{
I_step_two(fraction,balloc,scale_index,fr);
if(single >= 0)
{
clip += (fr->synth_mono)( (real *) fraction[single],pcm_sample,pcm_point);
}
else {
int p1=*pcm_point;
clip += (fr->synth)( (real *) fraction[0],0,pcm_sample,&p1);
clip += (fr->synth)( (real *) fraction[1],1,pcm_sample,pcm_point);
}
}
return clip;
}