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562
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1 /*
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2 layer1.c: the layer 1 decoder
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3
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4 copyright 1995-2007 by the mpg123 project - free software under the terms of the LGPL 2.1
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5 see COPYING and AUTHORS files in distribution or http://mpg123.org
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6 initially written by Michael Hipp
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7
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8 may have a few bugs after last optimization ...
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9 */
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10
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11 #include "mpg123lib_intern.h"
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12 #include "getbits.h"
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13
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14 void I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)
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15 {
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16 unsigned int *ba=balloc;
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17 unsigned int *sca = (unsigned int *) scale_index;
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18
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19 if(fr->stereo == 2) {
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20 int i;
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21 int jsbound = fr->jsbound;
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22 for (i=0;i<jsbound;i++) {
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23 *ba++ = getbits(fr, 4);
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24 *ba++ = getbits(fr, 4);
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25 }
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26 for (i=jsbound;i<SBLIMIT;i++)
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27 *ba++ = getbits(fr, 4);
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28
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29 ba = balloc;
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30
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31 for (i=0;i<jsbound;i++) {
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32 if ((*ba++))
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33 *sca++ = getbits(fr, 6);
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34 if ((*ba++))
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35 *sca++ = getbits(fr, 6);
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36 }
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37 for (i=jsbound;i<SBLIMIT;i++)
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38 if ((*ba++)) {
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39 *sca++ = getbits(fr, 6);
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40 *sca++ = getbits(fr, 6);
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41 }
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42 }
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43 else {
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44 int i;
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45 for (i=0;i<SBLIMIT;i++)
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46 *ba++ = getbits(fr, 4);
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47 ba = balloc;
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48 for (i=0;i<SBLIMIT;i++)
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49 if ((*ba++))
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50 *sca++ = getbits(fr, 6);
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51 }
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52 }
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53
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54 void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT],
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55 unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)
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56 {
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57 int i,n;
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58 int smpb[2*SBLIMIT]; /* values: 0-65535 */
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59 int *sample;
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60 register unsigned int *ba;
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61 register unsigned int *sca = (unsigned int *) scale_index;
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62
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63 if(fr->stereo == 2) {
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64 int jsbound = fr->jsbound;
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65 register real *f0 = fraction[0];
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66 register real *f1 = fraction[1];
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67 ba = balloc;
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68 for (sample=smpb,i=0;i<jsbound;i++) {
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69 if ((n = *ba++))
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70 *sample++ = getbits(fr, n+1);
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71 if ((n = *ba++))
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72 *sample++ = getbits(fr, n+1);
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73 }
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74 for (i=jsbound;i<SBLIMIT;i++)
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75 if ((n = *ba++))
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76 *sample++ = getbits(fr, n+1);
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77
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78 ba = balloc;
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79 for (sample=smpb,i=0;i<jsbound;i++) {
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80 if((n=*ba++))
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81 *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * fr->muls[n+1][*sca++];
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82 else
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83 *f0++ = 0.0;
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84 if((n=*ba++))
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85 *f1++ = (real) ( ((-1)<<n) + (*sample++) + 1) * fr->muls[n+1][*sca++];
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86 else
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87 *f1++ = 0.0;
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88 }
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89 for (i=jsbound;i<SBLIMIT;i++) {
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90 if ((n=*ba++)) {
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91 real samp = ( ((-1)<<n) + (*sample++) + 1);
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92 *f0++ = samp * fr->muls[n+1][*sca++];
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93 *f1++ = samp * fr->muls[n+1][*sca++];
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94 }
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95 else
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96 *f0++ = *f1++ = 0.0;
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97 }
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98 for(i=fr->down_sample_sblimit;i<32;i++)
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99 fraction[0][i] = fraction[1][i] = 0.0;
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100 }
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101 else {
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102 register real *f0 = fraction[0];
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103 ba = balloc;
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104 for (sample=smpb,i=0;i<SBLIMIT;i++)
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105 if ((n = *ba++))
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106 *sample++ = getbits(fr, n+1);
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107 ba = balloc;
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108 for (sample=smpb,i=0;i<SBLIMIT;i++) {
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109 if((n=*ba++))
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110 *f0++ = (real) ( ((-1)<<n) + (*sample++) + 1) * fr->muls[n+1][*sca++];
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111 else
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112 *f0++ = 0.0;
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113 }
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114 for(i=fr->down_sample_sblimit;i<32;i++)
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115 fraction[0][i] = 0.0;
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116 }
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117 }
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118
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119 int do_layer1(mpg123_handle *fr)
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120 {
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121 int clip=0;
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122 int i,stereo = fr->stereo;
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123 unsigned int balloc[2*SBLIMIT];
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124 unsigned int scale_index[2][SBLIMIT];
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125 ALIGNED(16) real fraction[2][SBLIMIT];
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126 int single = fr->single;
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127
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128 fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32;
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129
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130 if(stereo == 1 || single == SINGLE_MIX) /* I don't see mixing handled here */
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131 single = SINGLE_LEFT;
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132
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133 I_step_one(balloc,scale_index,fr);
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134
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135 for (i=0;i<SCALE_BLOCK;i++)
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136 {
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137 I_step_two(fraction,balloc,scale_index,fr);
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138
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139 if(single != SINGLE_STEREO)
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140 {
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141 clip += (fr->synth_mono)( (real *) fraction[single], fr);
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142 }
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143 else
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144 {
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145 clip += (fr->synth)( (real *) fraction[0], 0, fr, 0);
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146 clip += (fr->synth)( (real *) fraction[1], 1, fr, 1);
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147 }
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148 }
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149
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150 return clip;
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151 }
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152
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153
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