160 lines
4.0 KiB
JavaScript
160 lines
4.0 KiB
JavaScript
"use strict";
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var WILLIAMS_SOUND_PRESETS = [
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{id:'swave.c', name:'Wavetable Synth'},
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];
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/****************************************************************************
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Midway/Williams Audio Boards
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----------------------------
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6809 MEMORY MAP
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Function Address R/W Data
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---------------------------------------------------------------
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Program RAM 0000-07FF R/W D0-D7
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Music (YM-2151) 2000-2001 R/W D0-D7
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6821 PIA 4000-4003 R/W D0-D7
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HC55516 clock low, digit latch 6000 W D0
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HC55516 clock high 6800 W xx
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Bank select 7800 W D0-D2
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Banked Program ROM 8000-FFFF R D0-D7
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****************************************************************************/
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var WilliamsSoundPlatform = function(mainElement) {
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var self = this;
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this.__proto__ = new BaseZ80Platform();
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var cpu, ram, rom, membus, iobus;
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var audio, master;
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var video, timer;
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var command = 0;
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var dac = 0;
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var dac_float = 0.0
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var current_buffer;
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var last_tstate;
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var pixels;
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var cpuFrequency = 18432000/6; // 3.072 MHz
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var cpuCyclesPerFrame = cpuFrequency/60;
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var cpuAudioFactor = 32;
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function fillBuffer() {
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var t = cpu.getTstates() / cpuAudioFactor;
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while (last_tstate < t) {
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current_buffer[last_tstate++] = dac_float;
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}
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}
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this.getPresets = function() {
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return WILLIAMS_SOUND_PRESETS;
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}
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this.start = function() {
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ram = new RAM(0x400);
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membus = {
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read: new AddressDecoder([
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[0x0000, 0x3fff, 0x3fff, function(a) { return rom ? rom[a] : null; }],
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[0x4000, 0x7fff, 0x3ff, function(a) { return ram.mem[a]; }]
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]),
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write: new AddressDecoder([
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[0x4000, 0x7fff, 0x3ff, function(a,v) { ram.mem[a] = v; }],
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]),
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isContended: function() { return false; },
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};
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iobus = {
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read: function(addr) {
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return command & 0xff;
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},
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write: function(addr, val) {
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dac = val & 0xff;
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dac_float = ((dac & 0x80) ? -256+dac : dac) / 128.0;
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fillBuffer();
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}
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};
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cpu = window.Z80({
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display: {},
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memory: membus,
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ioBus: iobus
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});
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audio = new SampleAudio(cpuFrequency / cpuAudioFactor);
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audio.callback = function(lbuf) {
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if (self.isRunning()) {
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cpu.setTstates(0);
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current_buffer = lbuf;
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last_tstate = 0;
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self.runCPU(cpu, lbuf.length * cpuAudioFactor);
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cpu.setTstates(lbuf.length * cpuAudioFactor); // TODO?
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fillBuffer();
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for (var i=0; i<256; i++) {
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var y = Math.round((current_buffer[i] * 127) + 128);
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pixels[i + y*256] = 0xff33ff33;
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}
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}
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};
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video = new RasterVideo(mainElement,256,256);
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video.create();
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video.setKeyboardEvents(function(key,code,flags) {
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var intr = (key-49);
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if (intr >= 0 && (flags & 1)) {
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command = intr & 0xff;
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cpu.reset();
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}
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});
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pixels = video.getFrameData();
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timer = new AnimationTimer(30, function() {
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if (self.isRunning()) {
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video.updateFrame();
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pixels.fill(0);
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}
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});
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}
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this.loadROM = function(title, data) {
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rom = padBytes(data, 0x4000);
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cpu.reset();
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}
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this.loadState = function(state) {
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cpu.loadState(state.c);
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ram.mem.set(state.b);
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}
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this.saveState = function() {
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return {
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c:self.getCPUState(),
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b:ram.mem.slice(0),
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};
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}
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this.getCPUState = function() {
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return cpu.saveState();
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}
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this.isRunning = function() {
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return timer.isRunning();
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}
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this.pause = function() {
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timer.stop();
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audio.stop();
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}
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this.resume = function() {
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timer.start();
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audio.start();
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}
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this.reset = function() {
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cpu.reset();
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if (!this.getDebugCallback()) cpu.setTstates(0); // TODO?
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}
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this.readAddress = function(addr) {
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return membus.read(addr); // TODO?
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}
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}
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PLATFORMS['sound_williams-z80'] = WilliamsSoundPlatform;
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