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Fix default target. Ensure m68k.h and z80.h are built before anything else when no dep info is available
author Michael Pavone <pavone@retrodev.com>
date Mon, 31 Mar 2025 21:06:18 -0700
parents eb588f22ec76
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 #include <math.h>
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2 #include "ym_common.h"
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3
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4 #ifdef __ANDROID__
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5 #define log2(x) (log(x)/log(2))
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6 #endif
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7
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8 //According to Nemesis, real hardware only uses a 256 entry quarter sine table; however,
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9 //memory is cheap so using a half sine table will probably save some cycles
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10 //a full sine table would be nice, but negative numbers don't get along with log2
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11 #define SINE_TABLE_SIZE 512
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12 static uint16_t sine_table[SINE_TABLE_SIZE];
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13 //Similar deal here with the power table for log -> linear conversion
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14 //According to Nemesis, real hardware only uses a 256 entry table for the fractional part
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15 //and uses the whole part as a shift amount.
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16 #define POW_TABLE_SIZE (1 << 13)
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17 static uint16_t pow_table[POW_TABLE_SIZE];
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18
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19 static uint16_t rate_table_base[] = {
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20 //main portion
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21 0,1,0,1,0,1,0,1,
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22 0,1,0,1,1,1,0,1,
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23 0,1,1,1,0,1,1,1,
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24 0,1,1,1,1,1,1,1,
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25 //top end
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26 1,1,1,1,1,1,1,1,
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27 1,1,1,2,1,1,1,2,
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28 1,2,1,2,1,2,1,2,
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29 1,2,2,2,1,2,2,2,
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30 };
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31
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32 uint16_t rate_table[64*8];
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33
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34 static uint8_t lfo_pm_base[][8] = {
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35 {0, 0, 0, 0, 0, 0, 0, 0},
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36 {0, 0, 0, 0, 4, 4, 4, 4},
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37 {0, 0, 0, 4, 4, 4, 8, 8},
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38 {0, 0, 4, 4, 8, 8, 0xc, 0xc},
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39 {0, 0, 4, 8, 8, 8, 0xc,0x10},
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40 {0, 0, 8, 0xc,0x10,0x10,0x14,0x18},
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41 {0, 0,0x10,0x18,0x20,0x20,0x28,0x30},
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42 {0, 0,0x20,0x30,0x40,0x40,0x50,0x60}
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43 };
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44 int16_t lfo_pm_table[128 * 32 * 8];
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45
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46 static uint16_t round_fixed_point(double value, int dec_bits)
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47 {
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48 return value * (1 << dec_bits) + 0.5;
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49 }
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50
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51 void ym_init_tables(void)
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52 {
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53 static uint8_t did_tbl_init;
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54 if (did_tbl_init) {
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55 return;
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56 }
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57 did_tbl_init = 1;
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58 //populate sine table
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59 for (int32_t i = 0; i < 512; i++) {
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60 double sine = sin( ((double)(i*2+1) / SINE_TABLE_SIZE) * M_PI_2 );
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61
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62 //table stores 4.8 fixed pointed representation of the base 2 log
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63 sine_table[i] = round_fixed_point(-log2(sine), 8);
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64 }
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65 //populate power table
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66 for (int32_t i = 0; i < POW_TABLE_SIZE; i++) {
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67 double linear = pow(2, -((double)((i & 0xFF)+1) / 256.0));
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68 int32_t tmp = round_fixed_point(linear, 11);
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69 int32_t shift = (i >> 8) - 2;
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70 if (shift < 0) {
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71 tmp <<= 0-shift;
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72 } else {
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73 tmp >>= shift;
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74 }
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75 pow_table[i] = tmp;
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76 }
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77 //populate envelope generator rate table, from small base table
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78 for (int rate = 0; rate < 64; rate++) {
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79 for (int cycle = 0; cycle < 8; cycle++) {
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80 uint16_t value;
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81 if (rate < 2) {
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82 value = 0;
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83 } else if (rate >= 60) {
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84 value = 8;
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85 } else if (rate < 8) {
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86 value = rate_table_base[((rate & 6) == 6 ? 16 : 0) + cycle];
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87 } else if (rate < 48) {
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88 value = rate_table_base[(rate & 0x3) * 8 + cycle];
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89 } else {
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90 value = rate_table_base[32 + (rate & 0x3) * 8 + cycle] << ((rate - 48) >> 2);
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91 }
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92 rate_table[rate * 8 + cycle] = value;
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93 }
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94 }
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95 //populate LFO PM table from small base table
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96 //seems like there must be a better way to derive this
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97 for (int freq = 0; freq < 128; freq++) {
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98 for (int pms = 0; pms < 8; pms++) {
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99 for (int step = 0; step < 32; step++) {
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100 int16_t value = 0;
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101 for (int bit = 0x40, shift = 0; bit > 0; bit >>= 1, shift++) {
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102 if (freq & bit) {
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103 value += lfo_pm_base[pms][(step & 0x8) ? 7-step & 7 : step & 7] >> shift;
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104 }
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105 }
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106 if (step & 0x10) {
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107 value = -value;
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108 }
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109 lfo_pm_table[freq * 256 + pms * 32 + step] = value;
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110 }
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111 }
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112 }
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113 }
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114
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115 int16_t ym_sine(uint16_t phase, int16_t mod, uint16_t env)
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116 {
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117 phase += mod;
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118 if (env > MAX_ENVELOPE) {
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119 env = MAX_ENVELOPE;
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120 }
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121 int16_t output = pow_table[sine_table[phase & 0x1FF] + env];
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122 if (phase & 0x200) {
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123 output = -output;
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124 }
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125 return output;
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126 }
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127
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128 int16_t ym_opl_wave(uint16_t phase, int16_t mod, uint16_t env, uint8_t waveform)
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129 {
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130 if (env > MAX_OPL_ENVELOPE) {
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131 env = MAX_OPL_ENVELOPE;
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132 }
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133
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134 int16_t output;
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135 switch (waveform)
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136 {
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137 default:
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138 case 0:
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139 output = pow_table[sine_table[phase & 0x1FF] + env];
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140 if (phase & 0x200) {
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141 output = -output;
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142 }
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143 break;
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144 case 1:
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145 if (phase & 0x200) {
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146 output = 0;
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147 } else {
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148 output = pow_table[sine_table[phase & 0x1FF] + env];
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149 }
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150 break;
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151 case 2:
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152 output = pow_table[sine_table[phase & 0x1FF] + env];
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153 break;
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154 case 3:
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155 if (phase & 0x100) {
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156 output = 0;
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157 } else {
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158 output = pow_table[sine_table[phase & 0xFF] + env];
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159 }
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160 break;
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161 case 4:
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162 if (phase & 0x200) {
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163 output = 0;
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164 } else {
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165 output = pow_table[sine_table[(phase & 0xFF) << 1] + env];
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166 if (phase & 0x100) {
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167 output = -output;
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168 }
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169 }
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170 break;
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171 case 5:
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172 if (phase & 0x200) {
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173 output = 0;
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174 } else {
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175 output = pow_table[sine_table[(phase & 0xFF) << 1] + env];
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176 }
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177 break;
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178 case 6:
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179 output = pow_table[env];
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180 if (phase & 0x200) {
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181 output = -output;
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diff changeset
182 }
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183 break;
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184 case 7:
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diff changeset
185 if (phase & 0x200) {
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186 output = -pow_table[((~phase) & 0x1FF) << 3 + env];
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diff changeset
187 } else {
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188 output = pow_table[(phase & 0x1FF) << 3 + env];
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parents:
diff changeset
189 }
3f58fec775df Initial work on YMF262 (aka OPL3) emulation
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parents:
diff changeset
190 break;
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Michael Pavone <pavone@retrodev.com>
parents:
diff changeset
191 }
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diff changeset
192 return output;
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parents:
diff changeset
193 }
2565
eb588f22ec76 More work on OPL3 emulation
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parents: 2558
diff changeset
194
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diff changeset
195 void start_envelope(ym_operator *op, ym_channel *channel)
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parents: 2558
diff changeset
196 {
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diff changeset
197 //Deal with "infinite" attack rates
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diff changeset
198 uint8_t rate = op->rates[PHASE_ATTACK];
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diff changeset
199 if (rate) {
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diff changeset
200 uint8_t ks = channel->keycode >> op->key_scaling;;
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parents: 2558
diff changeset
201 rate = rate*2 + ks;
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parents: 2558
diff changeset
202 }
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parents: 2558
diff changeset
203 if (rate >= 62) {
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parents: 2558
diff changeset
204 op->env_phase = PHASE_DECAY;
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diff changeset
205 op->envelope = 0;
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parents: 2558
diff changeset
206 } else {
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parents: 2558
diff changeset
207 op->env_phase = PHASE_ATTACK;
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parents: 2558
diff changeset
208 }
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parents: 2558
diff changeset
209 }
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parents: 2558
diff changeset
210
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parents: 2558
diff changeset
211 void keyon(ym_operator *op, ym_channel *channel)
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parents: 2558
diff changeset
212 {
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parents: 2558
diff changeset
213 start_envelope(op, channel);
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
214 op->phase_counter = 0;
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
215 op->inverted = op->ssg & SSG_INVERT;
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parents: 2558
diff changeset
216 }
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parents: 2558
diff changeset
217
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
218 void keyoff(ym_operator *op)
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
219 {
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parents: 2558
diff changeset
220 op->env_phase = PHASE_RELEASE;
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
221 if (op->inverted) {
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
222 //Nemesis says the inversion state doesn't change here, but I don't see how that is observable either way
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parents: 2558
diff changeset
223 op->inverted = 0;
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Michael Pavone <pavone@retrodev.com>
parents: 2558
diff changeset
224 op->envelope = (SSG_CENTER - op->envelope) & MAX_ENVELOPE;
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parents: 2558
diff changeset
225 }
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parents: 2558
diff changeset
226 }