Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 | 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 264x 264x 264x 264x | // Code ported from Beebem (C to .js) by Jason Robson
const AUDIO_BUFFER_SIZE = 256;
const RAM_SIZE = 2048;
const WAVE_TABLE_SIZE = 128;
const WAVE_TABLES = 14;
const NUM_CHANNELS = 16;
const CHANNEL_REG_OFFSET = WAVE_TABLES * WAVE_TABLE_SIZE;
const CHANNEL_ROW_SIZE = 128;
// Control register bits
const CTRL_STEREO_POS = 0xf;
const CTRL_INVERT_WAVE = 1 << 4;
const CTRL_MODULATE_ADJ = 1 << 5;
// Data bits
const DATA_SIGN = 1 << 7;
const DATA_VALUE = 0x7f;
const FREQ_DISABLE = 1 << 0;
const NOT_FREQ_DISABLE = 0xfe;
// Channel register sets
const REG_SET_NORMAL = 0;
const REG_SET_ALT = 1;
export class Music5000 {
constructor(onBuffer) {
this._onBufferMusic5000 = onBuffer;
this.waveRam = new Uint8Array(RAM_SIZE);
this.phaseRam = new Uint32Array(NUM_CHANNELS);
this.cycleCount = 0;
this.curCh = 0;
this.activeRegSet = REG_SET_NORMAL;
this.sampleLeft = 0;
this.sampleRight = 0;
this.chordBase = [0, 8.25, 24.75, 57.75, 123.75, 255.75, 519.75, 1047.75];
this.stepInc = [0.5, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0];
this.stereoLeft = [0, 0, 0, 0, 0, 0, 0, 0, 100, 100, 100, 83, 67, 50, 33, 17];
this.stereoRight = [100, 100, 100, 100, 100, 100, 100, 100, 0, 0, 0, 17, 33, 50, 67, 83];
this.D2ATable = new Uint16Array(128);
this.sampleBuffer = new Float64Array(AUDIO_BUFFER_SIZE);
this.position = 0;
// Helper functions to access the register set and wavetable
this.cReg_freqLow = function (channel, regSet) {
return this.waveRam[CHANNEL_REG_OFFSET + regSet * CHANNEL_ROW_SIZE + 0 * NUM_CHANNELS + channel];
};
this.cReg_freqMedium = function (channel, regSet) {
return this.waveRam[CHANNEL_REG_OFFSET + regSet * CHANNEL_ROW_SIZE + 1 * NUM_CHANNELS + channel];
};
this.cReg_freqHigh = function (channel, regSet) {
return this.waveRam[CHANNEL_REG_OFFSET + regSet * CHANNEL_ROW_SIZE + 2 * NUM_CHANNELS + channel];
};
this.cReg_waveformReg = function (channel, regSet) {
return this.waveRam[CHANNEL_REG_OFFSET + regSet * CHANNEL_ROW_SIZE + 5 * NUM_CHANNELS + channel];
};
this.cReg_amplitudeReg = function (channel, regSet) {
return this.waveRam[CHANNEL_REG_OFFSET + regSet * CHANNEL_ROW_SIZE + 6 * NUM_CHANNELS + channel];
};
this.cReg_controlReg = function (channel, regSet) {
return this.waveRam[CHANNEL_REG_OFFSET + regSet * CHANNEL_ROW_SIZE + 7 * NUM_CHANNELS + channel];
};
this.waveTableVal = function (table, b) {
return this.waveRam[table * WAVE_TABLE_SIZE + b];
};
}
reset(hard) {
if (hard) {
console.log("Music 5000: initialisation");
// Build the D2A table
let i = 0;
for (let chord = 0; chord < 8; chord++) {
let val = this.chordBase[chord];
for (let step = 0; step < 16; step++) {
this.D2ATable[i] = Math.floor(val * 4); // Multiply up to get an integer
val += this.stepInc[chord];
i++;
}
}
}
// Clear RAM
for (let w = 0; w < RAM_SIZE; w++) {
this.waveRam[w] = 0;
}
for (let p = 0; p < NUM_CHANNELS; p++) {
this.phaseRam[p] = 0;
}
}
read(page, addr) {
// Bit0 unused
const offset = ((page & 0x0e) << 7) + addr;
return this.waveRam[offset];
}
write(page, addr, value) {
// Bit0 unused
const offset = ((page & 0x0e) << 7) + (addr & 0xff);
this.waveRam[offset] = value;
}
polltime(cycles) {
let c4d, freq, offset, wavetable, amplitude, control, data, sign, pos;
// Convert 2MHz 6502 cycles to 6MHz Music5000 cycles
this.cycleCount += cycles * 3;
// Need 8 cycles to update a channel
while (this.cycleCount >= 8) {
// Update phase for active register set
if (this.cReg_freqLow(this.curCh, this.activeRegSet) & FREQ_DISABLE) {
this.phaseRam[this.curCh] = 0;
c4d = 0;
} else {
freq =
(this.cReg_freqHigh(this.curCh, this.activeRegSet) << 16) +
(this.cReg_freqMedium(this.curCh, this.activeRegSet) << 8) +
(this.cReg_freqLow(this.curCh, this.activeRegSet) & NOT_FREQ_DISABLE);
this.phaseRam[this.curCh] += freq;
c4d = this.phaseRam[this.curCh] & (1 << 24);
this.phaseRam[this.curCh] &= 0xffffff;
}
// Pull wave sample out for the active register set
offset = (this.phaseRam[this.curCh] >> 17) & 0x7f;
wavetable = this.cReg_waveformReg(this.curCh, this.activeRegSet) >> 4;
data = this.waveTableVal(wavetable, offset);
amplitude = this.cReg_amplitudeReg(this.curCh, this.activeRegSet);
control = this.cReg_controlReg(this.curCh, this.activeRegSet);
sign = data & DATA_SIGN;
data &= DATA_VALUE;
// Modulate the next channel?
if (control & CTRL_MODULATE_ADJ && (sign || c4d)) this.activeRegSet = REG_SET_ALT;
else this.activeRegSet = REG_SET_NORMAL;
if (amplitude > 0x80) amplitude = 0x80;
data = (data * amplitude) / 0x80;
let sample = this.D2ATable[parseInt(data)];
if (control & CTRL_INVERT_WAVE) sign ^= DATA_SIGN;
if (sign) sample = -sample;
// Stereo
pos = control & CTRL_STEREO_POS;
this.sampleLeft += (sample * this.stereoLeft[pos]) / 100;
this.sampleRight += (sample * this.stereoRight[pos]) / 100;
this.curCh++;
if (this.curCh === NUM_CHANNELS) {
this.curCh = 0;
this.activeRegSet = REG_SET_NORMAL;
// Range check
if (this.sampleLeft < -32768) this.sampleLeft = -32768;
else if (this.sampleLeft > 32767) this.sampleLeft = 32767;
if (this.sampleRight < -32768) this.sampleRight = -32768;
else if (this.sampleRight > 32767) this.sampleRight = 32767;
this.sampleBuffer[this.position++] = this.sampleLeft;
this.sampleBuffer[this.position++] = this.sampleRight;
if (this.position === AUDIO_BUFFER_SIZE) {
this._onBufferMusic5000(this.sampleBuffer);
this.position = 0;
}
this.sampleLeft = 0;
this.sampleRight = 0;
}
this.cycleCount -= 8;
}
}
}
export class FakeMusic5000 {
constructor() {
this.reset = function () {};
this.polltime = function () {};
this.read = function () {
return 0;
};
this.write = function () {};
}
}
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