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261
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1 /*
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2 * Mpeg Layer-1,2,3 audio decoder
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3 * ------------------------------
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4 * copyright (c) 1995,1996,1997 by Michael Hipp, All rights reserved.
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5 * See also 'README'
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6 *
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7 * slighlty optimized for machines without autoincrement/decrement.
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8 * The performance is highly compiler dependend. Maybe
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9 * the decode.c version for 'normal' processor may be faster
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10 * even for Intel processors.
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11 */
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12
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13 #include <stdlib.h>
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14 #include <math.h>
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15 #include <string.h>
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16
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17 #include "mpg123_sdlsound.h"
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18 #include "mpglib_sdlsound.h"
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19
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20 extern struct mpstr *gmp;
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21
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22 /* old WRITE_SAMPLE */
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23 #define WRITE_SAMPLE(samples,sum,clip) \
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24 if( (sum) > 32767.0) { *(samples) = 0x7fff; (clip)++; } \
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25 else if( (sum) < -32768.0) { *(samples) = -0x8000; (clip)++; } \
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26 else { *(samples) = sum; }
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27
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28 int synth_1to1_mono(real *bandPtr,unsigned char *samples,int *pnt)
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29 {
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30 short samples_tmp[64];
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31 short *tmp1 = samples_tmp;
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32 int i,ret;
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33 int pnt1 = 0;
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34
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35 ret = synth_1to1(bandPtr,0,(unsigned char *) samples_tmp,&pnt1);
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36 samples += *pnt;
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37
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38 for(i=0;i<32;i++) {
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39 *( (short *) samples) = *tmp1;
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40 samples += 2;
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41 tmp1 += 2;
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42 }
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43 *pnt += 64;
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44
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45 return ret;
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46 }
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47
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48
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49 int synth_1to1(real *bandPtr,int channel,unsigned char *out,int *pnt)
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50 {
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51 static const int step = 2;
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52 int bo;
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53 short *samples = (short *) (out + *pnt);
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54
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55 real *b0,(*buf)[0x110];
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56 int clip = 0;
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57 int bo1;
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58
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59 bo = gmp->synth_bo;
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60
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61 if(!channel) {
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62 bo--;
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63 bo &= 0xf;
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64 buf = gmp->synth_buffs[0];
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65 }
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66 else {
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67 samples++;
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68 buf = gmp->synth_buffs[1];
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69 }
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70
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71 if(bo & 0x1) {
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72 b0 = buf[0];
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73 bo1 = bo;
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74 dct64(buf[1]+((bo+1)&0xf),buf[0]+bo,bandPtr);
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75 }
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76 else {
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77 b0 = buf[1];
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78 bo1 = bo+1;
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79 dct64(buf[0]+bo,buf[1]+bo+1,bandPtr);
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80 }
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81
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82 gmp->synth_bo = bo;
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83
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84 {
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85 register int j;
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86 real *window = decwin + 16 - bo1;
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87
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88 for (j=16;j;j--,b0+=0x10,window+=0x20,samples+=step)
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89 {
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90 real sum;
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91 sum = window[0x0] * b0[0x0];
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92 sum -= window[0x1] * b0[0x1];
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93 sum += window[0x2] * b0[0x2];
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94 sum -= window[0x3] * b0[0x3];
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95 sum += window[0x4] * b0[0x4];
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96 sum -= window[0x5] * b0[0x5];
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97 sum += window[0x6] * b0[0x6];
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98 sum -= window[0x7] * b0[0x7];
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99 sum += window[0x8] * b0[0x8];
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100 sum -= window[0x9] * b0[0x9];
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101 sum += window[0xA] * b0[0xA];
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102 sum -= window[0xB] * b0[0xB];
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103 sum += window[0xC] * b0[0xC];
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104 sum -= window[0xD] * b0[0xD];
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105 sum += window[0xE] * b0[0xE];
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106 sum -= window[0xF] * b0[0xF];
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107
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108 WRITE_SAMPLE(samples,sum,clip);
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109 }
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110
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111 {
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112 real sum;
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113 sum = window[0x0] * b0[0x0];
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114 sum += window[0x2] * b0[0x2];
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115 sum += window[0x4] * b0[0x4];
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116 sum += window[0x6] * b0[0x6];
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117 sum += window[0x8] * b0[0x8];
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118 sum += window[0xA] * b0[0xA];
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119 sum += window[0xC] * b0[0xC];
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120 sum += window[0xE] * b0[0xE];
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121 WRITE_SAMPLE(samples,sum,clip);
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122 b0-=0x10,window-=0x20,samples+=step;
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123 }
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124 window += bo1<<1;
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125
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126 for (j=15;j;j--,b0-=0x10,window-=0x20,samples+=step)
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127 {
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128 real sum;
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129 sum = -window[-0x1] * b0[0x0];
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130 sum -= window[-0x2] * b0[0x1];
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131 sum -= window[-0x3] * b0[0x2];
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132 sum -= window[-0x4] * b0[0x3];
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133 sum -= window[-0x5] * b0[0x4];
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134 sum -= window[-0x6] * b0[0x5];
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135 sum -= window[-0x7] * b0[0x6];
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136 sum -= window[-0x8] * b0[0x7];
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137 sum -= window[-0x9] * b0[0x8];
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138 sum -= window[-0xA] * b0[0x9];
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139 sum -= window[-0xB] * b0[0xA];
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140 sum -= window[-0xC] * b0[0xB];
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141 sum -= window[-0xD] * b0[0xC];
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142 sum -= window[-0xE] * b0[0xD];
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143 sum -= window[-0xF] * b0[0xE];
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144 sum -= window[-0x0] * b0[0xF];
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145
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146 WRITE_SAMPLE(samples,sum,clip);
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147 }
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148 }
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149 *pnt += 128;
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150
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151 return clip;
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152 }
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153
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