266 lines
6.5 KiB
JavaScript
266 lines
6.5 KiB
JavaScript
"use strict";
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var ATARIVEC_PRESETS = [
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]
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var AtariVectorPlatform = function(mainElement) {
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var self = this;
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var cpuFrequency = 1500000.0;
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var cpuCyclesPerNMI = 6000;
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var cpuCyclesPerFrame = Math.round(cpuFrequency/60);
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var cpu, cpuram, dvgram, rom, vecrom, bus, dvg;
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var video, audio, timer;
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var clock;
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var switches = new RAM(16).mem;
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var nmicount = cpuCyclesPerNMI;
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this.__proto__ = new Base6502Platform();
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this.getPresets = function() {
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return ATARIVEC_PRESETS;
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}
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this.start = function() {
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cpu = new jt.M6502();
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cpuram = new RAM(0x400);
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dvgram = new RAM(0x2000);
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//switches[5] = 0xff;
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//switches[7] = 0xff;
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// bus
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bus = {
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read: function(address) {
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address &= 0x7fff;
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if (address >= 0x6800 && address <= 0x7fff) {
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return rom[address - 0x6800];
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} else if (address <= 0x3ff) {
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return cpuram.mem[address];
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} else if (address >= 0x5000 && address <= 0x5fff) {
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return vecrom[address - 0x5000];
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} else if (address >= 0x4000 && address <= 0x5fff) {
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return dvgram.mem[address - 0x4000];
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} else if (address >= 0x2000 && address <= 0x3fff) {
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if (address == 0x2001)
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return ((clock/500) & 1) ? 0xff : 0x00;
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else if (address >= 0x2000 && address <= 0x2007)
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return switches[address - 0x2000];
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else if (address >= 0x2400 && address <= 0x2407)
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return switches[address - 0x2400 + 8];
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}
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return 0xff;
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},
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write: function(address, val) {
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address &= 0x7fff;
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if (address < 0x3ff) {
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cpuram.mem[address] = val;
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} else if (address >= 0x4000 && address <= 0x5fff) {
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dvgram.mem[address - 0x4000] = val;
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} else if (address >= 0x3000 && address <= 0x3fff) {
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//console.log(address.toString(16), val);
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if (address == 0x3000) dvg.runUntilHalt();
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// TODO: draw asynchronous or allow poll of HALT ($2002)
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}
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}
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};
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cpu.connectBus(bus);
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// create video/audio
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video = new VectorVideo(mainElement,1024,1024);
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dvg = new DVGStateMachine(bus, video);
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audio = new SampleAudio(cpuFrequency);
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video.start();
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timer = new AnimationTimer(60, function() {
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video.clear();
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// 262.5 scanlines per frame
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var iaddr = 0x4000;
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var iofs = 0;
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var debugCond = self.getDebugCallback();
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clock = 0;
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for (var i=0; i<cpuCyclesPerFrame; i++) {
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if (debugCond && debugCond()) { debugCond = null; }
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clock++;
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if (--nmicount == 0) {
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//console.log("NMI", cpu.saveState());
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var n = cpu.setNMIAndWait();
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clock += n;
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nmicount = cpuCyclesPerNMI - n;
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//console.log(n, clock, nmicount);
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}
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cpu.clockPulse();
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//cpu.executeInstruction();
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}
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});
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video.setKeyboardEvents(function(key,code,flags) {
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var KEY2ADDR = {
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16: 3, // shift
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32: 4, // space
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53: 8+0, // 5
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54: 8+1, // 6
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55: 8+2, // 7
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49: 8+3, // 1
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50: 8+4, // 2
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38: 8+5,
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39: 8+6,
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37: 8+7,
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};
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var addr = KEY2ADDR[key];
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//console.log(key,flags,addr);
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if (addr >= 0) {
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switches[addr] = (flags&1) ? 0xff : 0x00;
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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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if(data.length != 0x2000) {
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throw "ROM length must be == 0x2000";
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}
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rom = data.slice(0,0x1800);
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vecrom = data.slice(0x1800,0x2000);
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this.reset();
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}
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this.getRasterPosition = function() {
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return {x:0, y:0};
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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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}
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this.resume = function() {
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timer.start();
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}
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this.reset = function() {
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this.clearDebug();
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cpu.reset();
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}
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this.readAddress = function(addr) {
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return bus.read(addr);
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}
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this.loadState = function(state) {
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cpu.loadState(state.c);
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cpuram.mem.set(state.cb);
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dvgram.mem.set(state.db);
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nmicount = state.nmic;
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}
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this.saveState = function() {
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return {
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c:cpu.saveState(),
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cb:cpuram.mem.slice(0),
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db:dvgram.mem.slice(0),
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nmic:nmicount
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}
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}
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this.getRAMForState = function(state) {
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return state.cb;
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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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}
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var DVGStateMachine = function(bus, video) {
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var self = this;
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var pc = 0;
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var x = 0;
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var y = 0;
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var gsc = 0;
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var bofs = 0x4000;
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var pcstack = [];
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var running = false;
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function readWord(a) {
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a &= 0xfff;
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return bus.read(a*2+bofs) + (bus.read(a*2+bofs+1) << 8);
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}
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function decodeSigned(w, o2) {
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var s = w & (1<<o2);
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w = w & ((1<<o2)-1);
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if (s)
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return -w;
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else
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return w;
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}
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this.go = function() {
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pc = 0;
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gsc = 7;
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running = true;
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}
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this.runUntilHalt = function() {
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this.go();
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for (var i=0; i<10000; i++) { // TODO
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if (!running) break;
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this.nextInstruction();
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}
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//console.log('DVG',i);
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}
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var GSCALES = [7, 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, 8];
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this.nextInstruction = function() {
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if (!running) return;
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var w = readWord(pc);
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var op = w >> 12;
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//console.log(hex(pc), hex(w));
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pc++;
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switch (op) {
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// VEC
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case 0:
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case 1:
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case 2:
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case 3:
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case 4:
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case 5:
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case 6:
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case 7:
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case 8:
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case 9: { // VCTR
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var sc = gsc + 9 - op;
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var w2 = readWord(pc++);
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var z = w2 >> 12;
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var x2 = x + ((decodeSigned(w2, 10) << 7) >> sc);
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var y2 = y + ((decodeSigned(w, 10) << 7) >> sc);
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video.drawLine(x, y, x2, y2, z);
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//console.log(pc.toString(16), w.toString(16), w2.toString(16), gsc, sc, x, y, x2, y2);
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x = x2;
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y = y2;
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break;
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}
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case 10: { // LABS
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var w2 = readWord(pc++);
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gsc = GSCALES[w2 >> 12];
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x = w2 & 0x3ff;
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y = w & 0x3ff;
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break;
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}
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case 11: // HALT
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running = false;
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break;
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case 13: // RTSL
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pc = pcstack.pop();
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break;
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case 12: // JSRL
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pcstack.push(pc);
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case 14: // JMPL
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pc = w & 0xfff;
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break;
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case 15: { // SVEC
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var sc = ((w>>11)&1) + ((w>>2)&2);
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sc = gsc - sc - 1;
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var x2 = x + ((decodeSigned(w, 2) << 7) >> sc);
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var y2 = y + ((decodeSigned(w>>8, 2) << 7) >> sc);
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var z = (w >> 4) & 0xf;
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video.drawLine(x, y, x2, y2, z);
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x = x2;
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y = y2;
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break;
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}
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}
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}
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}
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