156 lines
3.7 KiB
C
156 lines
3.7 KiB
C
/*
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layer1.c: the layer 1 decoder
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copyright 1995-2009 by the mpg123 project - free software under the terms of the LGPL 2.1
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see COPYING and AUTHORS files in distribution or http://mpg123.org
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initially written by Michael Hipp
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may have a few bugs after last optimization ...
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*/
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#include "mpg123lib_intern.h"
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#include "getbits.h"
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static void I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)
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{
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unsigned int *ba=balloc;
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unsigned int *sca = (unsigned int *) scale_index;
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if(fr->stereo == 2)
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{
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int i;
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int jsbound = fr->jsbound;
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for(i=0;i<jsbound;i++)
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{
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*ba++ = getbits(fr, 4);
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*ba++ = getbits(fr, 4);
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}
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for(i=jsbound;i<SBLIMIT;i++) *ba++ = getbits(fr, 4);
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ba = balloc;
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for(i=0;i<jsbound;i++)
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{
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if ((*ba++))
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*sca++ = getbits(fr, 6);
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if ((*ba++))
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*sca++ = getbits(fr, 6);
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}
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for (i=jsbound;i<SBLIMIT;i++)
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if((*ba++))
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{
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*sca++ = getbits(fr, 6);
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*sca++ = getbits(fr, 6);
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}
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}
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else
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{
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int i;
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for(i=0;i<SBLIMIT;i++) *ba++ = getbits(fr, 4);
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ba = balloc;
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for (i=0;i<SBLIMIT;i++)
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if ((*ba++))
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*sca++ = getbits(fr, 6);
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}
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}
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static void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)
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{
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int i,n;
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int smpb[2*SBLIMIT]; /* values: 0-65535 */
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int *sample;
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register unsigned int *ba;
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register unsigned int *sca = (unsigned int *) scale_index;
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if(fr->stereo == 2)
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{
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int jsbound = fr->jsbound;
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register real *f0 = fraction[0];
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register real *f1 = fraction[1];
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ba = balloc;
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for(sample=smpb,i=0;i<jsbound;i++)
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{
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if((n = *ba++)) *sample++ = getbits(fr, n+1);
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if((n = *ba++)) *sample++ = getbits(fr, n+1);
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}
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for(i=jsbound;i<SBLIMIT;i++)
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if((n = *ba++))
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*sample++ = getbits(fr, n+1);
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ba = balloc;
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for(sample=smpb,i=0;i<jsbound;i++)
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{
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if((n=*ba++))
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*f0++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1), fr->muls[n+1][*sca++]);
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else *f0++ = DOUBLE_TO_REAL(0.0);
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if((n=*ba++))
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*f1++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1), fr->muls[n+1][*sca++]);
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else *f1++ = DOUBLE_TO_REAL(0.0);
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}
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for(i=jsbound;i<SBLIMIT;i++)
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{
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if((n=*ba++))
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{
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real samp = DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1);
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*f0++ = REAL_MUL_SCALE_LAYER12(samp, fr->muls[n+1][*sca++]);
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*f1++ = REAL_MUL_SCALE_LAYER12(samp, fr->muls[n+1][*sca++]);
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}
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else *f0++ = *f1++ = DOUBLE_TO_REAL(0.0);
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}
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for(i=fr->down_sample_sblimit;i<32;i++)
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fraction[0][i] = fraction[1][i] = 0.0;
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}
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else
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{
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register real *f0 = fraction[0];
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ba = balloc;
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for(sample=smpb,i=0;i<SBLIMIT;i++)
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if ((n = *ba++))
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*sample++ = getbits(fr, n+1);
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ba = balloc;
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for(sample=smpb,i=0;i<SBLIMIT;i++)
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{
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if((n=*ba++))
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*f0++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15( ((-1)<<n) + (*sample++) + 1), fr->muls[n+1][*sca++]);
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else *f0++ = DOUBLE_TO_REAL(0.0);
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}
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for(i=fr->down_sample_sblimit;i<32;i++)
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fraction[0][i] = DOUBLE_TO_REAL(0.0);
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}
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}
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int do_layer1(mpg123_handle *fr)
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{
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int clip=0;
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int i,stereo = fr->stereo;
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unsigned int balloc[2*SBLIMIT];
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unsigned int scale_index[2][SBLIMIT];
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real (*fraction)[SBLIMIT] = fr->layer1.fraction; /* fraction[2][SBLIMIT] */
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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 == SINGLE_MIX) /* I don't see mixing handled here */
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single = SINGLE_LEFT;
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I_step_one(balloc,scale_index,fr);
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for(i=0;i<SCALE_BLOCK;i++)
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{
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I_step_two(fraction,balloc,scale_index,fr);
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if(single != SINGLE_STEREO)
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clip += (fr->synth_mono)(fraction[single], fr);
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else
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clip += (fr->synth_stereo)(fraction[0], fraction[1], fr);
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}
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return clip;
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}
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