Mercurial > SDL_sound_CoreAudio
annotate decoders/mpglib/layer1.c @ 298:c92c07e07636
Renamed from common.c.
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Mon, 25 Mar 2002 20:51:32 +0000 |
| parents | ad4c8f34136a |
| children |
| rev | line source |
|---|---|
| 261 | 1 /* |
| 2 * Mpeg Layer-1 audio decoder | |
| 3 * -------------------------- | |
| 4 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README' | |
| 5 * near unoptimzed ... | |
| 6 * | |
| 7 * may have a few bugs after last optimization ... | |
| 8 * | |
| 9 */ | |
| 10 | |
| 11 #include "mpg123_sdlsound.h" | |
| 12 | |
| 13 void I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],struct frame *fr) | |
| 14 { | |
| 15 unsigned int *ba=balloc; | |
| 16 unsigned int *sca = (unsigned int *) scale_index; | |
| 17 | |
| 18 if(fr->stereo) { | |
| 19 int i; | |
| 20 int jsbound = fr->jsbound; | |
| 21 for (i=0;i<jsbound;i++) { | |
| 22 *ba++ = getbits(4); | |
| 23 *ba++ = getbits(4); | |
| 24 } | |
| 25 for (i=jsbound;i<SBLIMIT;i++) | |
| 26 *ba++ = getbits(4); | |
| 27 | |
| 28 ba = balloc; | |
| 29 | |
| 30 for (i=0;i<jsbound;i++) { | |
| 31 if ((*ba++)) | |
| 32 *sca++ = getbits(6); | |
| 33 if ((*ba++)) | |
| 34 *sca++ = getbits(6); | |
| 35 } | |
| 36 for (i=jsbound;i<SBLIMIT;i++) | |
| 37 if ((*ba++)) { | |
| 38 *sca++ = getbits(6); | |
| 39 *sca++ = getbits(6); | |
| 40 } | |
| 41 } | |
| 42 else { | |
| 43 int i; | |
| 44 for (i=0;i<SBLIMIT;i++) | |
| 45 *ba++ = getbits(4); | |
| 46 ba = balloc; | |
| 47 for (i=0;i<SBLIMIT;i++) | |
| 48 if ((*ba++)) | |
| 49 *sca++ = getbits(6); | |
| 50 } | |
| 51 } | |
| 52 | |
| 53 void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT], | |
| 54 unsigned int scale_index[2][SBLIMIT],struct frame *fr) | |
| 55 { | |
| 56 int i,n; | |
| 57 int smpb[2*SBLIMIT]; /* values: 0-65535 */ | |
| 58 int *sample; | |
| 59 register unsigned int *ba; | |
| 60 register unsigned int *sca = (unsigned int *) scale_index; | |
| 61 | |
| 62 if(fr->stereo) { | |
| 63 int jsbound = fr->jsbound; | |
| 64 register real *f0 = fraction[0]; | |
| 65 register real *f1 = fraction[1]; | |
| 66 ba = balloc; | |
| 67 for (sample=smpb,i=0;i<jsbound;i++) { | |
| 68 if ((n = *ba++)) | |
| 69 *sample++ = getbits(n+1); | |
| 70 if ((n = *ba++)) | |
| 71 *sample++ = getbits(n+1); | |
| 72 } | |
| 73 for (i=jsbound;i<SBLIMIT;i++) | |
| 74 if ((n = *ba++)) | |
| 75 *sample++ = getbits(n+1); | |
| 76 | |
| 77 ba = balloc; | |
| 78 for (sample=smpb,i=0;i<jsbound;i++) { | |
| 79 if((n=*ba++)) | |
| 80 *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++]; | |
| 81 else | |
| 82 *f0++ = 0.0; | |
| 83 if((n=*ba++)) | |
| 84 *f1++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++]; | |
| 85 else | |
| 86 *f1++ = 0.0; | |
| 87 } | |
| 88 for (i=jsbound;i<SBLIMIT;i++) { | |
| 89 if ((n=*ba++)) { | |
| 90 real samp = ( ((-1)<<n) + (*sample++) + 1); | |
| 91 *f0++ = samp * muls[n+1][*sca++]; | |
| 92 *f1++ = samp * muls[n+1][*sca++]; | |
| 93 } | |
| 94 else | |
| 95 *f0++ = *f1++ = 0.0; | |
| 96 } | |
| 97 } | |
| 98 else { | |
| 99 register real *f0 = fraction[0]; | |
| 100 ba = balloc; | |
| 101 for (sample=smpb,i=0;i<SBLIMIT;i++) | |
| 102 if ((n = *ba++)) | |
| 103 *sample++ = getbits(n+1); | |
| 104 ba = balloc; | |
| 105 for (sample=smpb,i=0;i<SBLIMIT;i++) { | |
| 106 if((n=*ba++)) | |
| 107 *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++]; | |
| 108 else | |
| 109 *f0++ = 0.0; | |
| 110 } | |
| 111 } | |
| 112 } | |
| 113 | |
|
281
ad4c8f34136a
Minor formatting updates.
Ryan C. Gordon <icculus@icculus.org>
parents:
279
diff
changeset
|
114 int do_layer1(struct frame *fr,unsigned char *pcm_sample, |
|
ad4c8f34136a
Minor formatting updates.
Ryan C. Gordon <icculus@icculus.org>
parents:
279
diff
changeset
|
115 int *pcm_point,struct mpstr *mp) |
| 261 | 116 { |
| 117 int clip=0; | |
| 118 int i,stereo = fr->stereo; | |
| 119 unsigned int balloc[2*SBLIMIT]; | |
| 120 unsigned int scale_index[2][SBLIMIT]; | |
| 121 real fraction[2][SBLIMIT]; | |
| 122 int single = fr->single; | |
| 123 | |
| 124 fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32; | |
| 125 | |
| 126 if(stereo == 1 || single == 3) | |
| 127 single = 0; | |
| 128 | |
| 129 I_step_one(balloc,scale_index,fr); | |
| 130 | |
| 131 for (i=0;i<SCALE_BLOCK;i++) | |
| 132 { | |
| 133 I_step_two(fraction,balloc,scale_index,fr); | |
| 134 | |
| 135 if(single >= 0) { | |
|
279
52b9f37998db
Removed global state variable; should be thread safe now.
Ryan C. Gordon <icculus@icculus.org>
parents:
261
diff
changeset
|
136 clip += synth_1to1_mono( (real*)fraction[single],pcm_sample,pcm_point,mp); |
| 261 | 137 } |
| 138 else { | |
| 139 int p1 = *pcm_point; | |
|
279
52b9f37998db
Removed global state variable; should be thread safe now.
Ryan C. Gordon <icculus@icculus.org>
parents:
261
diff
changeset
|
140 clip += synth_1to1( (real*)fraction[0],0,pcm_sample,&p1,mp); |
|
52b9f37998db
Removed global state variable; should be thread safe now.
Ryan C. Gordon <icculus@icculus.org>
parents:
261
diff
changeset
|
141 clip += synth_1to1( (real*)fraction[1],1,pcm_sample,pcm_point,mp); |
| 261 | 142 } |
| 143 } | |
| 144 | |
| 145 return clip; | |
| 146 } | |
| 147 | |
| 148 |