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| Rev | Author | Line No. | Line |
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| 2 | pj | 1 | /* |
| 2 | * Mpeg Layer-1 audio decoder |
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| 3 | * -------------------------- |
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| 4 | * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README' |
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| 5 | * near unoptimzed ... |
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| 6 | * |
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| 7 | * may have a few bugs after last optimization ... |
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| 8 | * |
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| 9 | */ |
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| 10 | |||
| 11 | #include "mpg123.h" |
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| 12 | |||
| 13 | void I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],struct frame *fr) |
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| 14 | { |
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| 15 | unsigned int *ba=balloc; |
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| 16 | unsigned int *sca = (unsigned int *) scale_index; |
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| 17 | |||
| 18 | if(fr->stereo) { |
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| 19 | int i; |
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| 20 | int jsbound = fr->jsbound; |
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| 21 | for (i=0;i<jsbound;i++) { |
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| 22 | *ba++ = getbits(4); |
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| 23 | *ba++ = getbits(4); |
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| 24 | } |
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| 25 | for (i=jsbound;i<SBLIMIT;i++) |
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| 26 | *ba++ = getbits(4); |
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| 27 | |||
| 28 | ba = balloc; |
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| 29 | |||
| 30 | for (i=0;i<jsbound;i++) { |
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| 31 | if ((*ba++)) |
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| 32 | *sca++ = getbits(6); |
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| 33 | if ((*ba++)) |
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| 34 | *sca++ = getbits(6); |
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| 35 | } |
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| 36 | for (i=jsbound;i<SBLIMIT;i++) |
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| 37 | if ((*ba++)) { |
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| 38 | *sca++ = getbits(6); |
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| 39 | *sca++ = getbits(6); |
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| 40 | } |
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| 41 | } |
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| 42 | else { |
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| 43 | int i; |
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| 44 | for (i=0;i<SBLIMIT;i++) |
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| 45 | *ba++ = getbits(4); |
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| 46 | ba = balloc; |
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| 47 | for (i=0;i<SBLIMIT;i++) |
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| 48 | if ((*ba++)) |
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| 49 | *sca++ = getbits(6); |
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| 50 | } |
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| 51 | } |
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| 52 | |||
| 53 | void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT], |
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| 54 | unsigned int scale_index[2][SBLIMIT],struct frame *fr) |
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| 55 | { |
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| 56 | int i,n; |
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| 57 | int smpb[2*SBLIMIT]; /* values: 0-65535 */ |
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| 58 | int *sample; |
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| 59 | register unsigned int *ba; |
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| 60 | register unsigned int *sca = (unsigned int *) scale_index; |
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| 61 | |||
| 62 | if(fr->stereo) { |
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| 63 | int jsbound = fr->jsbound; |
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| 64 | register real *f0 = fraction[0]; |
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| 65 | register real *f1 = fraction[1]; |
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| 66 | ba = balloc; |
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| 67 | for (sample=smpb,i=0;i<jsbound;i++) { |
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| 68 | if ((n = *ba++)) |
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| 69 | *sample++ = getbits(n+1); |
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| 70 | if ((n = *ba++)) |
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| 71 | *sample++ = getbits(n+1); |
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| 72 | } |
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| 73 | for (i=jsbound;i<SBLIMIT;i++) |
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| 74 | if ((n = *ba++)) |
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| 75 | *sample++ = getbits(n+1); |
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| 76 | |||
| 77 | ba = balloc; |
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| 78 | for (sample=smpb,i=0;i<jsbound;i++) { |
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| 79 | if((n=*ba++)) |
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| 80 | *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++]; |
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| 81 | else |
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| 82 | *f0++ = 0.0; |
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| 83 | if((n=*ba++)) |
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| 84 | *f1++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++]; |
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| 85 | else |
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| 86 | *f1++ = 0.0; |
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| 87 | } |
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| 88 | for (sample=smpb,i=jsbound;i<SBLIMIT;i++) { |
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| 89 | if ((n=*ba++)) { |
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| 90 | real samp = ( ((-1)<<n) + (*sample++) + 1); |
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| 91 | *f0++ = samp * muls[n+1][*sca++]; |
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| 92 | *f1++ = samp * muls[n+1][*sca++]; |
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| 93 | } |
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| 94 | else |
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| 95 | *f0++ = *f1++ = 0.0; |
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| 96 | } |
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| 97 | for(i=SBLIMIT>>fr->down_sample;i<32;i++) |
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| 98 | fraction[0][i] = fraction[1][i] = 0.0; |
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| 99 | } |
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| 100 | else { |
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| 101 | register real *f0 = fraction[0]; |
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| 102 | ba = balloc; |
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| 103 | for (sample=smpb,i=0;i<SBLIMIT;i++) |
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| 104 | if ((n = *ba++)) |
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| 105 | *sample++ = getbits(n+1); |
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| 106 | ba = balloc; |
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| 107 | for (sample=smpb,i=0;i<SBLIMIT;i++) { |
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| 108 | if((n=*ba++)) |
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| 109 | *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * muls[n+1][*sca++]; |
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| 110 | else |
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| 111 | *f0++ = 0.0; |
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| 112 | } |
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| 113 | for(i=SBLIMIT>>fr->down_sample;i<32;i++) |
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| 114 | fraction[0][i] = 0.0; |
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| 115 | } |
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| 116 | } |
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| 117 | |||
| 118 | int do_layer1(struct frame *fr,int outmode,struct audio_info_struct *ai) |
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| 119 | { |
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| 120 | int clip=0; |
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| 121 | int i,stereo = fr->stereo; |
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| 122 | unsigned int balloc[2*SBLIMIT]; |
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| 123 | unsigned int scale_index[2][SBLIMIT]; |
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| 124 | real fraction[2][SBLIMIT]; |
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| 125 | int single = fr->single; |
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| 126 | |||
| 127 | if(stereo == 1 || single == 3) |
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| 128 | single = 0; |
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| 129 | |||
| 130 | I_step_one(balloc,scale_index,fr); |
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| 131 | |||
| 132 | for (i=0;i<SCALE_BLOCK;i++) |
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| 133 | { |
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| 134 | I_step_two(fraction,balloc,scale_index,fr); |
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| 135 | |||
| 136 | if(single >= 0) |
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| 137 | { |
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| 138 | clip += (fr->synth_mono)( (real *) fraction[single],pcm_sample+pcm_point); |
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| 139 | } |
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| 140 | else { |
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| 141 | clip += (fr->synth)( (real *) fraction[0],0,pcm_sample+pcm_point); |
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| 142 | clip += (fr->synth)( (real *) fraction[1],1,pcm_sample+pcm_point); |
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| 143 | } |
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| 144 | pcm_point += fr->block_size; |
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| 145 | |||
| 146 | if(pcm_point == audiobufsize) |
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| 147 | audio_flush(outmode,ai); |
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| 148 | } |
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| 149 | |||
| 150 | return clip; |
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| 151 | } |
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| 152 | |||
| 153 |