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/* |
layer1.c: the layer 1 decoder |
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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 |
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may have a few bugs after last optimization ... |
*/ |
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#include "mpg123.h" |
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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; |
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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); |
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ba = balloc; |
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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); |
} |
} |
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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; |
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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); |
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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; |
} |
} |
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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; |
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fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32; |
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if(stereo == 1 || single == 3) |
single = 0; |
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I_step_one(balloc,scale_index,fr); |
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for (i=0;i<SCALE_BLOCK;i++) |
{ |
I_step_two(fraction,balloc,scale_index,fr); |
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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; |
} |
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