/* * Mpeg Layer-1 audio decoder * -------------------------- * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README' * This file has been copied from mpglib. * near unoptimzed ... * * may have a few bugs after last optimization ... * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA */ #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) { 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) { 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; } } 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; } } } int do_layer1(struct frame *fr,unsigned char *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 += synth_1to1_mono( (real*)fraction[single],pcm_sample,pcm_point); } else { int p1 = *pcm_point; clip += synth_1to1( (real*)fraction[0],0,pcm_sample,&p1); clip += synth_1to1( (real*)fraction[1],1,pcm_sample,pcm_point); } } return clip; }