annotate fmgen/psg.c @ 7:ceda140f42fb

Remove the embedded getopt implementation.
author Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
date Mon, 08 Sep 2014 17:23:31 +0200
parents 8ad174416431
children
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1 // FIXME: move ugly-ass legalese somewhere where it won't be seen
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2 // by anyone other than lawyers. (/dev/null would be ideal but sadly
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3 // we live in an imperfect world).
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4 /* Copyright (c) 2012/2013, Peter Barfuss
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5 All rights reserved.
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6
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7 Redistribution and use in source and binary forms, with or without
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8 modification, are permitted provided that the following conditions are met:
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9
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10 1. Redistributions of source code must retain the above copyright notice, this
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11 list of conditions and the following disclaimer.
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12 2. Redistributions in binary form must reproduce the above copyright notice,
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13 this list of conditions and the following disclaimer in the documentation
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14 and/or other materials provided with the distribution.
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15
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16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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17 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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18 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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19 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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20 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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21 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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22 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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23 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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24 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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25 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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26
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27 // Quick, somewhat hacky PSG implementation. Seems to work fine in most cases.
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28 // Known bugs: volume *may* still be off for a lot of samples. Importantly,
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29 // waveform volume is too quiet but setting it at the correct volume makes
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30 // the noise volume too loud and vice-versa. I *think* what I have currently
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31 // is mostly correct (I'm basing this mostly on how good Strawberry Crisis
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32 // sounds with the given settings), but it's possible that more fine-tuning
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33 // is needed. Apart from that, this is probably the sketchiest part of all
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34 // of my emulator code, but then again there's a bit-exact VHDL core of
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35 // the YM2149F/AY-3-8910, so while I do want to make this as good
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36 // as the code in opna.c, it's the lowest-priority of all of the code here.
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37 // --bofh
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38 #include <stdint.h>
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39 #include <stdlib.h>
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40 #include <string.h>
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41 #include <math.h>
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42 #include <unistd.h>
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43 #include "op.h"
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44 #include "psg.h"
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45 #define Max(a,b) ((a>b)?a:b)
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46 #define Min(a,b) ((a<b)?a:b)
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47
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48 // ---------------------------------------------------------------------------
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49 // テーブル
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50 //
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51 int EmitTable[0x20] = { -1, };
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52 uint enveloptable[16][64] = { 0, };
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53
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54 // ---------------------------------------------------------------------------
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55 // PSG reset to power-on defaults
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56 //
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57 void PSGReset(PSG *psg)
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58 {
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59 int i;
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60 for (i=0; i<14; i++)
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61 PSGSetReg(psg, i, 0);
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62 PSGSetReg(psg, 7, 0xff);
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63 PSGSetReg(psg, 14, 0xff);
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64 PSGSetReg(psg, 15, 0xff);
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65 }
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66
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67 // ---------------------------------------------------------------------------
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68 // This code is strongly inspired by some random PSG emulator code I found,
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69 // and is probably not the optimal way to define periods. It *is* at least
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70 // among the fastest, given that it uses the hilarious hack of using the
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71 // integer overflow on a 32-bit unsigned integer to compute ""moduli"".
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72 //
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73 void PSGSetClock(PSG *psg, uint32_t clock, uint32_t rate)
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74 {
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75 psg->tperiodbase = (uint32_t)((1 << toneshift ) / 4.0f * clock / rate);
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76 psg->eperiodbase = (uint32_t)((1 << envshift ) / 4.0f * clock / rate);
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77
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78 // 各データの更新
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79 int tmp;
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80 tmp = ((psg->reg[0] + psg->reg[1] * 256) & 0xfff);
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81 psg->speriod[0] = tmp ? psg->tperiodbase / tmp : psg->tperiodbase;
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82 tmp = ((psg->reg[2] + psg->reg[3] * 256) & 0xfff);
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83 psg->speriod[1] = tmp ? psg->tperiodbase / tmp : psg->tperiodbase;
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84 tmp = ((psg->reg[4] + psg->reg[5] * 256) & 0xfff);
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85 psg->speriod[2] = tmp ? psg->tperiodbase / tmp : psg->tperiodbase;
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86 tmp = psg->reg[6] & 0x1f;
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87 psg->nperiod = tmp;
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88 tmp = ((psg->reg[11] + psg->reg[12] * 256) & 0xffff);
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89 psg->eperiod = tmp ? psg->eperiodbase / tmp : psg->eperiodbase * 2;
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90 }
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91
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92 // ---------------------------------------------------------------------------
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93 // エンベロープ波形テーブル
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94 //
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95 static uint8_t table3[4] = { 0, 1, -1, 0 };
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96 void MakeEnvelopTable(void)
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97 {
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98 // 0 lo 1 up 2 down 3 hi
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99 static uint8_t table1[16*2] =
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100 {
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101 2,0, 2,0, 2,0, 2,0, 1,0, 1,0, 1,0, 1,0,
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102 2,2, 2,0, 2,1, 2,3, 1,1, 1,3, 1,2, 1,0,
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103 };
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104 int i, j;
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105
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106 if (!enveloptable[0][0])
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107 {
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108 uint* ptr = enveloptable[0];
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109
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110 for (i=0; i<16*2; i++)
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111 {
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112 uint8_t v = ((table1[i] & 0x2) ? 31 : 0);
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113
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114 for (j=0; j<32; j++)
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115 {
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116 *ptr++ = EmitTable[v];
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117 v += table3[table1[i]];
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118 }
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119 }
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120 }
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121 }
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122
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123 // ---------------------------------------------------------------------------
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124 // Sets the channel output mask for the PSG device.
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125 // c is a bitvector where the 3 LSBs are set to 0 to disable a given
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126 // PSG channel and 1 to enable it.
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127 // TODO: Possibly allow enabling tone/noise output for each channel independently?
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128 //
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129 void PSGSetChannelMask(PSG *psg, int c)
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130 {
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131 int i;
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132 psg->mask = c;
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133 for (i=0; i<3; i++)
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134 psg->olevel[i] = psg->mask & (1 << i) ? EmitTable[(psg->reg[8+i] & 15) * 2 + 1] : 0;
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135 }
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136
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137 // ---------------------------------------------------------------------------
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138 // Sets the PSG volume. It's a fairly standard dB -> internal linear scale
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139 // conversion, followed by generating a table with volume levels.
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140 // The "magic number" 1.189207115 is just sqrt(sqrt(2))
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141 // TODO: is this table really needed? We have fast floating-point now.
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142 //
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143 void SetVolumePSG(PSG *psg, int volume)
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144 {
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145 int i;
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146 float base = 0x4000 / 3.0f * expf((float)M_LN10*(volume / 40.0f));
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147 for (i=31; i>=2; i--)
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148 {
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149 EmitTable[i] = lrintf(base);
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150 base /= 1.189207115f;
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151 }
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152 EmitTable[1] = 0;
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153 EmitTable[0] = 0;
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154 MakeEnvelopTable();
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155
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156 PSGSetChannelMask(psg, psg->mask);
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157 }
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158
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159 // ---------------------------------------------------------------------------
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160 // PSG register set routine. Mostly just what you'd expect from reading the manual.
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161 // Fairly boring code overall. regnum can be 0 - 15, data can be 0x00 - 0xFF.
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162 // (This should not be surprising - the YM2149F *did* use an 8-bit bus, after all).
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163 // Interesting quirk: the task of register 7 (channel enable/disable) is basically
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164 // entirely duplicated by other registers, to the point where you can basically
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165 // just ignore any writes to register 7 entirely. I save it here in case some
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166 // braindead routine wants to read its value and do something based on that
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167 // (Another curiosity: register 7 on the PSG appears to be the only register
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168 // between *both* the OPNA and the PSG which is actually *read from* by
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169 // pmdwin.cpp and not just written to. Amusingly enough, the only reason
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170 // that it is ever read is so that it can then OR something with what it just read
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171 // and then write that back to register 7. Hilarity).
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172 // HACK ALERT: The output levels for channels 0 and 1 are increased by a factor of 4
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173 // to make them match the actual chip in loudness, but without causing the noise channel
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174 // to overtake everything in intensity. This is almost certainly wrong, and moreover
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175 // it assumes that channel 2 will be playing back Speak Board effects which usually means
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176 // drum kit only (for the most part, at least), and not being used as a separate tonal
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177 // channel in its own right. To the best of my knowledge, this does hold for all of ZUN's
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178 // songs, however, once you step outside that set of music, it's trivial to find
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179 // all sorts of counterexamples to that assumption. Therefore, this should be fixed ASAP.
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180 //
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181 void PSGSetReg(PSG *psg, uint8_t regnum, uint8_t data)
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182 {
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183 if (regnum < 0x10)
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184 {
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185 psg->reg[regnum] = data;
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186 switch (regnum)
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187 {
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188 int tmp;
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189
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190 case 0: // ChA Fine Tune
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191 case 1: // ChA Coarse Tune
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192 tmp = ((psg->reg[0] + psg->reg[1] * 256) & 0xfff);
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193 psg->speriod[0] = tmp ? psg->tperiodbase / tmp : psg->tperiodbase;
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194 break;
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195
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196 case 2: // ChB Fine Tune
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197 case 3: // ChB Coarse Tune
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198 tmp = ((psg->reg[2] + psg->reg[3] * 256) & 0xfff);
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199 psg->speriod[1] = tmp ? psg->tperiodbase / tmp : psg->tperiodbase;
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200 break;
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201
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202 case 4: // ChC Fine Tune
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203 case 5: // ChC Coarse Tune
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204 tmp = ((psg->reg[4] + psg->reg[5] * 256) & 0xfff);
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205 psg->speriod[2] = tmp ? psg->tperiodbase / tmp : psg->tperiodbase;
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206 break;
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207
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208 case 6: // Noise generator control
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209 data &= 0x1f;
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210 psg->nperiod = data;
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211 break;
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212
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213 case 8:
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214 psg->olevel[0] = psg->mask & 1 ? EmitTable[(data & 15) * 2 + 1] : 0;
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215 break;
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216
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217 case 9:
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218 psg->olevel[1] = psg->mask & 2 ? EmitTable[(data & 15) * 2 + 1] : 0;
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219 break;
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220
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221 case 10:
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222 psg->olevel[2] = psg->mask & 4 ? EmitTable[(data & 15) * 2 + 1] : 0;
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223 break;
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224
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225 case 11: // Envelope period
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226 case 12:
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227 tmp = ((psg->reg[11] + psg->reg[12] * 256) & 0xffff);
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228 psg->eperiod = tmp ? psg->eperiodbase / tmp : psg->eperiodbase * 2;
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229 break;
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230
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231 case 13: // Envelope shape
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232 psg->ecount = 0;
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233 psg->envelop = enveloptable[data & 15];
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234 break;
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235 }
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236 }
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237 }
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238
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239 // ---------------------------------------------------------------------------
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240 // Init code. Set volume to 0, reset the chip, enable all channels, seed the RNG.
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241 // RNG seed lifted from MAME's YM2149F emulation routine, appears to be correct.
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242 //
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243 void PSGInit(PSG *psg)
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244 {
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245 SetVolumePSG(psg, 0);
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246 psg->rng = 14231;
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247 psg->ncount = 0;
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248 PSGReset(psg);
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249 psg->mask = 0x3f;
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250 }
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251
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252 // ---------------------------------------------------------------------------
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253 // The main output routine for the PSG emulation.
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254 // dest should be an array of size nsamples, and of type Sample
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255 // (one of int16_t, int32_t or float - any will work here without causing
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256 // clipping/precision problems).
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257 // Everything is implemented using some form of fixed-point arithmetic
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258 // that currently needs no more than 32-bits for its implementation,
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259 // but I'm pretty certain that you can get by with much less than that
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260 // and still have mostly correct-to-fully-correct emulation.
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261 //
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262 // TODO: In the future, test the veracity of the above statement. Moreover,
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263 // if it turns out to be correct, rewrite this routine to not use more than
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264 // the required precision. This is irrelevant for any PC newer than, well,
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265 // a 386DX/68040, but important for efficient hardware implementation.
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266 //
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267 void PSGMix(PSG *psg, Sample* dest, uint32_t nsamples)
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268 {
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269 uint8_t chenable[3];
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270 uint8_t r7 = ~psg->reg[7];
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271 int i;
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272
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273 if ((r7 & 0x3f) | ((psg->reg[8] | psg->reg[9] | psg->reg[10]) & 0x1f)) {
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274 chenable[0] = (r7 & 0x01) && (psg->speriod[0] <= (1 << toneshift));
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275 chenable[1] = (r7 & 0x02) && (psg->speriod[1] <= (1 << toneshift));
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276 chenable[2] = (r7 & 0x04) && (psg->speriod[2] <= (1 << toneshift));
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277
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278 int noise, sample;
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279 uint env;
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280 uint* p1 = ((psg->mask & 1) && (psg->reg[ 8] & 0x10)) ? &env : &psg->olevel[0];
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281 uint* p2 = ((psg->mask & 2) && (psg->reg[ 9] & 0x10)) ? &env : &psg->olevel[1];
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282 uint* p3 = ((psg->mask & 4) && (psg->reg[10] & 0x10)) ? &env : &psg->olevel[2];
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283 #define SCOUNT(ch) (psg->scount[ch] >> toneshift)
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284
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285 if (p1 != &env && p2 != &env && p3 != &env) {
3
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286 // ノイズ有り
0
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287 for (i=0; i<nsamples; i++) {
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288 psg->ncount++;
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289 if(psg->ncount >= psg->nperiod) {
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290 if(psg->rng & 1)
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291 psg->rng ^= 0x24000;
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292 psg->rng >>= 1;
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293 psg->ncount = 0;
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294 }
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295 noise = (psg->rng & 1);
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296 sample = 0;
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297 {
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298 int x, y, z;
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299 x = ((SCOUNT(0) & chenable[0]) | ((r7 >> 3) & noise)) - 1; // 0 or -1
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300 sample += (psg->olevel[0] + x) ^ x;
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301 psg->scount[0] += psg->speriod[0];
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302 y = ((SCOUNT(1) & chenable[1]) | ((r7 >> 4) & noise)) - 1;
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303 sample += (psg->olevel[1] + y) ^ y;
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304 psg->scount[1] += psg->speriod[1];
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305 z = ((SCOUNT(2) & chenable[2]) | ((r7 >> 5) & noise)) - 1;
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306 sample += (psg->olevel[2] + z) ^ z;
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307 psg->scount[2] += psg->speriod[2];
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308 }
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309 dest[0] += sample;
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310 dest += 1;
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311 }
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312
3
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313 // エンベロープの計算をさぼった帳尻あわせ
0
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314 psg->ecount = (psg->ecount >> 8) + (psg->eperiod >> 8) * nsamples;
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315 if (psg->ecount >= (1 << (envshift+6-8))) {
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316 if ((psg->reg[0x0d] & 0x0b) != 0x0a)
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317 psg->ecount |= (1 << (envshift+5-8));
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318 psg->ecount &= (1 << (envshift+6-8)) - 1;
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319 }
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320 psg->ecount <<= 8;
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321 } else {
3
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322 // エンベロープあり
0
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323 for (i=0; i<nsamples; i++) {
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324 psg->ncount++;
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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325 if(psg->ncount >= psg->nperiod) {
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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326 if(psg->rng & 1)
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327 psg->rng ^= 0x24000;
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328 psg->rng >>= 1;
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329 psg->ncount = 0;
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330 }
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331 noise = (psg->rng & 1);
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332 sample = 0;
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333 {
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334 env = psg->envelop[psg->ecount >> envshift];
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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335 psg->ecount += psg->eperiod;
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336 if (psg->ecount >= (1 << (envshift+6))) {
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337 if ((psg->reg[0x0d] & 0x0b) != 0x0a)
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338 psg->ecount |= (1 << (envshift+5));
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339 psg->ecount &= (1 << (envshift+6)) - 1;
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340 }
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341 int x, y, z;
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342 x = ((SCOUNT(0) & chenable[0]) | ((r7 >> 3) & noise)) - 1; // 0 or -1
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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343 sample += (*p1 + x) ^ x;
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344 psg->scount[0] += psg->speriod[0];
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345 y = ((SCOUNT(1) & chenable[1]) | ((r7 >> 4) & noise)) - 1;
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346 sample += (*p2 + y) ^ y;
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347 psg->scount[1] += psg->speriod[1];
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348 z = ((SCOUNT(2) & chenable[2]) | ((r7 >> 5) & noise)) - 1;
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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349 sample += (*p3 + z) ^ z;
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350 psg->scount[2] += psg->speriod[2];
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351 }
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352 dest[0] += sample;
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353 dest += 1;
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
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354 }
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents:
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355 }
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents:
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356 }
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents:
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357 }
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Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
parents:
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358