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| -rw-r--r-- | README.md | 13 | ||||
| -rw-r--r-- | emu8910.ts | 917 |
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diff --git a/README.md b/README.md new file mode 100644 index 0000000..adee73c --- /dev/null +++ b/README.md @@ -0,0 +1,13 @@ +### emu8910 + +This repository contains a Typescript implementation of General Instrument's [AY-3-8910](https://en.wikipedia.org/wiki/General_Instrument_AY-3-8910) PSG (programmable sound generator). +It implements most of the PSG's original registers. A datasheet can be found [here](http://map.grauw.nl/resources/sound/generalinstrument_ay-3-8910.pdf). + +Sound output is achieved in the browser through an AudioContext() hook. <br> +This emulator also adds interrupt support (with variable frequency) for updating the PSG's registers. + +This repository currently lacks a working example of the emulator which I plan to add in the future. + +Files: + +* emu8910.ts - Core emulator implementation diff --git a/emu8910.ts b/emu8910.ts new file mode 100644 index 0000000..a057c2d --- /dev/null +++ b/emu8910.ts @@ -0,0 +1,917 @@ +// Copyright (C) +// Author: Dylan Muller + +const YM_CLOCK_ZX = 1750000; +const FIR = + +[-0.000058, + 0.000024, + 0.000088, + -0.000003, + -0.000116, + -0.000035, + 0.000137, + 0.000089, + -0.000143, + -0.000156, + 0.000126, + 0.000231, + -0.000079, + -0.000304, + -0.000002, + 0.000362, + 0.000117, + -0.000390, + -0.000261, + 0.000375, + 0.000423, + -0.000304, + -0.000585, + 0.000168, + 0.000726, + 0.000033, + -0.000821, + -0.000294, + 0.000845, + 0.000596, + -0.000775, + -0.000915, + 0.000593, + 0.001215, + -0.000292, + -0.001456, + -0.000121, + 0.001594, + 0.000626, + -0.001589, + -0.001186, + 0.001405, + 0.001751, + -0.001025, + -0.002258, + 0.000444, + 0.002638, + 0.000316, + -0.002820, + -0.001211, + 0.002743, + 0.002175, + -0.002360, + -0.003117, + 0.001647, + 0.003933, + -0.000611, + -0.004512, + -0.000705, + 0.004744, + 0.002222, + -0.004535, + -0.003825, + 0.003817, + 0.005369, + -0.002558, + -0.006686, + 0.000773, + 0.007598, + 0.001470, + -0.007929, + -0.004048, + 0.007523, + 0.006783, + -0.006258, + -0.009449, + 0.004059, + 0.011782, + -0.000908, + -0.013485, + -0.003144, + 0.014246, + 0.007982, + -0.013741, + -0.013425, + 0.011632, + 0.019237, + -0.007546, + -0.025141, + 0.000999, + 0.030835, + 0.008787, + -0.036013, + -0.023415, + 0.040387, + 0.047128, + -0.043707, + -0.095861, + 0.045780, + 0.314841, + 0.453515, + 0.314841, + 0.045780, + -0.095861, + -0.043707, + 0.047128, + 0.040387, + -0.023415, + -0.036013, + 0.008787, + 0.030835, + 0.000999, + -0.025141, + -0.007546, + 0.019237, + 0.011632, + -0.013425, + -0.013741, + 0.007982, + 0.014246, + -0.003144, + -0.013485, + -0.000908, + 0.011782, + 0.004059, + -0.009449, + -0.006258, + 0.006783, + 0.007523, + -0.004048, + -0.007929, + 0.001470, + 0.007598, + 0.000773, + -0.006686, + -0.002558, + 0.005369, + 0.003817, + -0.003825, + -0.004535, + 0.002222, + 0.004744, + -0.000705, + -0.004512, + -0.000611, + 0.003933, + 0.001647, + -0.003117, + -0.002360, + 0.002175, + 0.002743, + -0.001211, + -0.002820, + 0.000316, + 0.002638, + 0.000444, + -0.002258, + -0.001025, + 0.001751, + 0.001405, + -0.001186, + -0.001589, + 0.000626, + 0.001594, + -0.000121, + -0.001456, + -0.000292, + 0.001215, + 0.000593, + -0.000915, + -0.000775, + 0.000596, + 0.000845, + -0.000294, + -0.000821, + 0.000033, + 0.000726, + 0.000168, + -0.000585, + -0.000304, + 0.000423, + 0.000375, + -0.000261, + -0.000390, + 0.000117, + 0.000362, + -0.000002, + -0.000304, + -0.000079, + 0.000231, + 0.000126, + -0.000156, + -0.000143, + 0.000089, + 0.000137, + -0.000035, + -0.000116, + -0.000003, + 0.000088, + 0.000024, + -0.000058] ; + + + +interface Channel{ + + port : number, + counter : number, + period : number, + volume : number, + pan : number, + tone : number, + noise : number, + envelope : number + +} + +interface Envelope{ + + counter : number, + period : number, + shape : number, + stub : any, + matrix : any, + strobe : number, + offset : number, + transient : number, + store : number, + step : number + +} + +interface Oscillator{ + + frequency: number, + scale : number, + cycle : number, + step : number + +} + +interface Interrupt{ + frequency : number, + routine : any, + cycle : number, +} + +class Interpolator{ + buffer : number[] = []; + + constructor(){ + for(let i = 0; i < 4; i++){ + this.buffer[i] = 0x0; + } + } + + step(x : number){ + let b = this.buffer; + b[0] = b[1]; + b[1] = b[2]; + b[2] = b[3]; + + b[3] = x; + } + + cubic(mu : number){ + + let b = this.buffer; + let a0,a1,a2,a3,mu2 = 0; + mu2 = mu * mu2; + a0 = b[3] - b[2] - b[0] + b[1]; + a1 = b[0] - b[1] - a0; + a2 = b[2] - b[0]; + a3 = b[1]; + + return (a0*mu*mu2 + a1*mu2 + a2*mu + a3); + } + +} + +// DC filter +class BiasFilter { + + samples : number[] =[]; + index : number = 0x0; + length : number = 0x0; + sum: number = 0x0; + attenuate : number = 0x0; + + constructor(length : number, attenuate : number){ + + this.length = length; + this.sum = 0x0; + + for(let i = 0; i < this.length; i++){ + this.samples[i] = 0x0; + } + this.attenuate = attenuate; + } + + step(x : number){ + let index = this.index; + let delta = x - this.samples[index]; + let attenuate = this.attenuate; + let avg = 0x0; + + this.sum += delta; + this.samples[index] = x; + + if(++this.index > (this.length - 1)){ + this.index = 0x0; + } + + avg = this.sum / this.length; + + return (x - avg) * (1/attenuate); + } +} + +class FirFilter { + buffer : number[] = []; + index : number = 0x0; + offset : number = 0x0; + length : number = 0x0; + m : number = 0x0; + h : number[] = []; + + constructor(h : number[], m : number){ + + this.length = h.length * m; + this.index = 0; + this.m = m; + this.h = h; + + let buffer = this.buffer; + for(let i = 0; i < this.length * 2; i++){ + buffer[i] = 0x0; + } + } + + step(samples : number []){ + + let index = this.index; + let buffer = this.buffer; + let length = this.length; + let m = this.m; + let h = this.h; + let y = 0x0; + let i = 0x0; + + this.offset = length - (index * m); + let sub = buffer.slice(this.offset); + this.index = (index + 1) % (length / m - 1); + for( i = m -1; i >=0; i--){ + buffer[this.offset + i] = samples[i]; + } + for( i = 0; i < h.length; i++){ + y += h[i] * sub[i]; + } + for( i = 0; i < m; i++){ + buffer[this.offset + length - m + i] = buffer[this.offset + i]; + } + + + return y; + + } + +} + +class AudioDriver { + + host : PSG49; + device : AudioContext; + context: ScriptProcessorNode; + frequency : number = 0x0; + filter : (BiasFilter | any)[]; + bias : number; + + constructor(host : PSG49){ + + this.device = new AudioContext(); + let device = this.device; + + this.filter = [ + + new BiasFilter(1024, 1.25), + new BiasFilter(1024, 1.25), + + device.createBiquadFilter(), + device.createBiquadFilter() + ]; + + let filter = this.filter; + + filter[2].type = "lowshelf"; + filter[2].frequency.value = 1500; + filter[2].gain.value = 3.35; + + filter[3].type = "lowpass"; + filter[3].frequency.value = 10000; + filter[3].Q.value = 1; + + this.frequency = device.sampleRate; + this.context = device.createScriptProcessor(4096,0,2); + this.context.onaudioprocess = this.update; + this.context.connect(filter[2]); + + filter[2].connect(filter[3]); + filter[3].connect(device.destination); + + this.host = host; + this.bias = 1/100; + + } + + update = function(ev : AudioProcessingEvent){ + + let ch0 = ev.outputBuffer.getChannelData(0); + let ch1 = ev.outputBuffer.getChannelData(1); + + let host = this.host; + let filter = this.filter; + let bias = this.bias; + let output = [0, 0]; + let port = [0, 0]; + + for(let i = 0; i < ch0.length; i++){ + + output = host.step(); + + port[0] = filter[0].step(output[0]); + port[1] = filter[1].step(output[1]); + + ch0[i] = bias + port[0]; + ch1[i] = bias + port[1]; + } + + }.bind(this); +} + +enum PSG49_LUT{ + + A_FINE, A_COARSE, + B_FINE, B_COARSE, + C_FINE, C_COARSE, + NOISE_PERIOD, + MIXER, + A_VOL, + B_VOL, + C_VOL, + ENV_FINE, + ENV_COARSE, + ENV_SHAPE + +} +class PSG49 { + + clock : Oscillator; + driver : AudioDriver; + interrupt : Interrupt; + channels: Channel[]; + envelope : Envelope; + fir : FirFilter[]; + oversample : number; + interpolate : Interpolator[]; + dac : number[]; + + // main register file + register = { + + A_FINE: 0x0, A_COARSE: 0x0, + B_FINE: 0x0, B_COARSE: 0x0, + C_FINE: 0x0, C_COARSE: 0x0, + + NOISE_PERIOD: 0x0, + + MIXER: 0x0, + + A_VOL: 0x0, + B_VOL: 0x0, + C_VOL: 0x0, + + ENV_FINE: 0x0, ENV_COARSE: 0x0, + ENV_SHAPE: 0x0, + + PORT_A: 0x0, + PORT_B: 0x0 + } + + constructor(clockRate : number, intRate : number){ + + this.driver = new AudioDriver(this); + this.interpolate = [ + new Interpolator(), + new Interpolator() + ]; + + let m = 8; + this.fir = [ + new FirFilter(FIR, m), + new FirFilter(FIR, m) + ]; + this.oversample = m; + + this.clock = { + frequency : clockRate, + scale : 1/16 * 2, + cycle : 0, + step : 0 + }; + + this.interrupt = { + frequency : intRate, + cycle : 0, + routine : ()=>{} + } + + this.envelope = { + strobe : 0, + transient : 0, + step : 0, + shape : 0, + offset : 0, + stub : [] + + } as Envelope; + + this.channels = [ + { + counter : 0x0, + pan : 0.5, + } as Channel, + { + counter : 0x0, + pan : 0.5 + } as Channel, + { + counter : 0x0, + pan : 0.5 + } as Channel, + + {counter : 0x0} as Channel + ] + + // seed noise generator + this.channels[3].port = 0x1; + + this.dac = []; + + this.build_dac(1.3, 40); + this.build_adsr(); + + } + + build_dac(decay : number, shift : number){ + let dac = this.dac; + let y = Math.sqrt(decay); + let z = shift/31; + + dac[0] = 0; + dac[1] = 0; + + for(let i = 2; i <= 31; i++){ + dac[i] = 1.0 / Math.pow(y, shift - (z*i) ); + } + } + + init_test(){ + let r = this.register; + + r.MIXER = 0b00111000; + r.A_VOL = 15; + //r.A_VOL |= 0x10; + r.A_FINE = 200; + //r.ENV_COARSE = 200; + } + + + build_adsr(){ + let envelope = this.envelope; + let stub = envelope.stub; + + stub.reset = (ev : Envelope)=>{ + let strobe = ev.strobe; + let transient = ev.transient; + + switch(ev.offset){ + + case 0x4: + transient = 0; + case 0x0: + ev.step = strobe ? transient : 31; + break; + case 0x5: + transient = 31; + case 0x1: + ev.step = strobe ? transient : 0; + break; + case 0x2: ev.step = 31; + break; + case 0x3: ev.step = 0; + break; + } + } + + stub.grow = (ev: Envelope)=>{ + + if(++ ev.step > 31 ){ + ev.strobe ^= 1; + ev.stub.reset(ev); + } + + }; + + stub.decay = (ev : Envelope)=>{ + if(-- ev.step < 0){ + ev.strobe ^= 1; + ev.stub.reset(ev); + } + + }; + + stub.hold = (ev : Envelope)=>{ } + + envelope.matrix = [ + + [stub.decay, stub.hold], + [stub.grow, stub.hold], + [stub.decay, stub.decay], + [stub.grow, stub.grow], + [stub.decay, stub.grow], + [stub.grow, stub.decay], + + ]; + } + + clamp(){ + let r = this.register; + + r.A_FINE &= 0xff; r.B_FINE &= 0xff; + r.C_FINE &= 0xff; r.ENV_FINE &= 0xff; + + r.A_COARSE &= 0xf; r.B_COARSE &=0xf; + r.C_COARSE &= 0xf; r.ENV_COARSE &= 0xff; + + r.A_VOL &= 0x1f; r.B_VOL &= 0x1f; + r.C_VOL &= 0x1f; + + r.NOISE_PERIOD &= 0x1f; r.MIXER &= 0x3f; + r.ENV_SHAPE &= 0xff; + + } + + map(){ + + let r = this.register; + let channel = this.channels; + let ev = this.envelope; + + let toneMask = [0x1,0x2,0x4]; + let noiseMask = [0x8,0x10,0x20]; + + this.clamp(); + // update tone channel period + channel[0].period = r.A_FINE | r.A_COARSE << 8; + channel[1].period = r.B_FINE | r.B_COARSE << 8; + channel[2].period = r.C_FINE | r.C_COARSE << 8; + + channel[0].volume = r.A_VOL & 0xf; + channel[1].volume = r.B_VOL & 0xf; + channel[2].volume = r.C_VOL & 0xf; + + for(let i = 0; i < 3; i++){ + let bit = r.MIXER & toneMask[i]; + channel[i].tone = bit ? 1 : 0; + } + + for(let i = 0; i < 3; i++){ + let bit = r.MIXER & noiseMask[i]; + channel[i].noise = bit ? 1 : 0; + } + + channel[0].envelope = (r.A_VOL & 0x10) ? 0 : 1; + channel[1].envelope = (r.B_VOL & 0x10) ? 0 : 1; + channel[2].envelope = (r.C_VOL & 0x10) ? 0 : 1; + + // update channel noise period + channel[3].period = r.NOISE_PERIOD << 1; + + ev.period = r.ENV_FINE | r.ENV_COARSE << 8; + ev.shape = r.ENV_SHAPE; + + + switch(ev.shape){ + + case 0x0: case 0x1: + case 0x2: case 0x3: + case 0x9: + ev.transient = 0; + ev.offset = 0; + r.ENV_SHAPE = 0xff; + break; + case 0xb: + ev.transient = 31; + ev.offset = 0; + r.ENV_SHAPE = 0xff; + break; + case 0x4: case 0x5: + case 0x6: case 0x7: + case 0xf: + ev.transient = 0; + ev.offset = 1; + r.ENV_SHAPE = 0xff; + case 0xd: + ev.transient = 31; + ev.offset = 1; + r.ENV_SHAPE = 0xff; + break; + case 0x8: + ev.offset = 2; + break; + case 0xc: + ev.offset = 3; + break; + case 0xa: + ev.offset = 4; + break; + case 0xe: + ev.offset = 5; + break; + + } + if(ev.shape != ev.store){ + ev.strobe = 0x0; + ev.counter = 0x0; + ev.stub.reset(ev); + + } + ev.store = r.ENV_SHAPE; + } + + step_tone(index : number){ + + let ch = this.channels[index % 3]; + let step = this.clock.step; + let port = ch.port; + + let period = (ch.period == 0x0) ? 0x1 : ch.period; + ch.counter += step; + + if(ch.counter >= period){ + // 50% duty cycle + port ^= 0x1; + ch.port = port; + ch.counter = 0x0; + } + + return ch.port; + + } + + step_envelope(){ + + let step = this.clock.step; + let ev = this.envelope; + + ev.counter += step; + + if(ev.counter >= ev.period){ + ev.matrix[ev.offset][ev.strobe](ev); + ev.counter = 0x0; + } + + return (ev.step); + } + + step_noise(){ + + let ch = this.channels[3]; + let step = this.clock.step; + let port = ch.port; + let period = (ch.period == 0) ? 1 : ch.period; + + ch.counter += step; + + if(ch.counter >= period){ + port ^= (((port & 1) ^ ((port >> 3) & 1)) << 17); + port >>= 1; + ch.port = port; + ch.counter = 0x0; + } + return ch.port & 1; + } + + step_mixer(){ + + let port = 0x0; + let output = [0.0, 0.0]; + let index = 0x0; + let ch = this.channels; + let noise = this.step_noise(); + let step = this.step_envelope(); + + for(let i = 0; i < 3; i++){ + + let volume = ch[i].volume; + let pan = ch[i].pan; + + port = this.step_tone(i) | ch[i].tone; + port &= noise | ch[i].noise; + + // todo: add dac volume table + //bit*=toneChannel[i].volume; + // mix each channel + + if(!ch[i].envelope){ + index = step; + }else{ + + index = volume * 2 + 1; + } + + port *= this.dac[index]; + + // clamp pan levels + // distortion over +1 ? + + if(pan > 0.9){ + pan = 0.9; + } + else if (pan < 0.1){ + pan = 0.1; + } + + output[0] += port * (1- pan) ; + output[1] += port * (pan) ; + + } + + return output; + } + + step(){ + + let output = []; + let clockStep = 0; + let intStep = 0; + let i = 0x0; + + let clock = this.clock; + let driver = this.driver; + let fir = this.fir; + let oversample = this.oversample; + let interpolate = this.interpolate; + let interrupt = this.interrupt; + + let x = clock.scale; + let fc = clock.frequency; + let fd = driver.frequency; + let fi = interrupt.frequency; + + clockStep = (fc * x) / fd; + clock.step = clockStep / oversample; + + intStep = fi/ fd; + + // add number of clock cycle + + interrupt.cycle += intStep; + // do we have clock cycles to process? + // if so process single clock cycle + + let sample_left = []; + let sample_right = []; + + for(i = 0; i < oversample; i++){ + sample_left[i] = 0x0; + sample_right[i] = 0x0; + } + + if(interrupt.cycle > 1){ + interrupt.cycle--; + interrupt.routine(); + interrupt.cycle = 0; + } + for(let i = 0; i < oversample; i++){ + clock.cycle += clockStep; + + if(clock.cycle > 1){ + clock.cycle--; + + this.map(); + output = this.step_mixer(); + + interpolate[0].step(output[0]); + interpolate[1].step(output[1]); + + } + sample_left[i] = interpolate[0].cubic(0.5); + sample_right[i] = interpolate[1].cubic(0.5); + + + } + output[0] = fir[0].step(sample_left); + output[1] = fir[1].step(sample_right); + + return output; + } + +} |