diff options
Diffstat (limited to 'mp3lib/layer1.c')
| -rw-r--r-- | mp3lib/layer1.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/mp3lib/layer1.c b/mp3lib/layer1.c new file mode 100644 index 0000000000..4af0933823 --- /dev/null +++ b/mp3lib/layer1.c @@ -0,0 +1,157 @@ +/* + * 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 ... + * + */ + +//#include "mpg123.h" + +static 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); + } +} + +static 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; + } + 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; + } +} + +static int do_layer1(struct frame *fr,int single) +{ + 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; + +// printf("do_layer1(0x%02X 0x%02X 0x%02X 0x%02X 0x%02X 0x%02X 0x%02X 0x%02X )\n", +// wordpointer[0],wordpointer[1],wordpointer[2],wordpointer[3],wordpointer[4],wordpointer[5],wordpointer[6],wordpointer[7]); + + 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; +} + + |