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Diffstat (limited to 'js.2/nes.js')
| -rw-r--r-- | js.2/nes.js | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/js.2/nes.js b/js.2/nes.js new file mode 100644 index 0000000..6b55d92 --- /dev/null +++ b/js.2/nes.js @@ -0,0 +1,208 @@ + +function NES() { + this.opts = { + preferredFrameRate: 60, + fpsInterval: 500, // Time between updating FPS in ms + showDisplay: true, + + emulateSound: false, + sampleRate: 44100, // Sound sample rate in hz + + CPU_FREQ_NTSC: 1789772.5,//1789772.72727272d; + CPU_FREQ_PAL: 1773447.4, + } + this.frameTime = 1000/this.opts.preferredFrameRate; + + this.cpu = new NES.CPU(this); + this.ppu = new NES.PPU(this); + this.papu = new NES.PAPU(this); + this.mmap = null; // set in loadRom() + this.keyboard = new NES.Keyboard(); + + $("#status").text("Initialised. Ready to load a ROM."); +} + + +NES.prototype = { + isRunning: false, + fpsFrameCount: 0, + limitFrames: true, + + // Resets the system. + reset: function() { + if(this.mmap != null) { + this.mmap.reset(); + } + + this.cpu.reset(); + this.ppu.reset(); + this.papu.reset(); + }, + + start: function() { + var self = this; + + if(this.rom != null && this.rom.valid) { + if (!this.isRunning) { + //$("#status").text("Running "+this.romFile) + this.isRunning = true; + + this.frameInterval = setInterval(function() { + self.frame(); + }, this.frameTime/2); + this.resetFps(); + this.printFps(); + this.fpsInterval = setInterval(function() { + self.printFps(); + }, this.opts.fpsInterval); + } + } + else { + alert("There is no ROM loaded, or it is invalid."); + } + }, + + frame: function() { + this.ppu.startFrame(); + var cycles = 0; + var emulateSound = nes.opts.emulateSound; + var cpu = this.cpu; + var ppu = this.ppu; + var papu = this.papu; + FRAMELOOP: for (;;) { + if (cpu.cyclesToHalt == 0) { + // Execute a CPU instruction + cycles = cpu.emulate(); + if (emulateSound) { + papu.clockFrameCounter(cycles); + } + cycles *= 3; + } + else { + if (cpu.cyclesToHalt > 8) { + cycles = 24; + if (emulateSound) { + papu.clockFrameCounter(8); + } + cpu.cyclesToHalt -= 8; + } + else { + cycles = cpu.cyclesToHalt * 3; + if (emulateSound) { + papu.clockFrameCounter(cpu.cyclesToHalt); + } + cpu.cyclesToHalt = 0; + } + } + + for(;cycles>0;cycles--){ + + if(ppu.curX == ppu.spr0HitX + && ppu.f_spVisibility==1 + && ppu.scanline-21 == ppu.spr0HitY){ + // Set sprite 0 hit flag: + ppu.setStatusFlag(ppu.STATUS_SPRITE0HIT,true); + } + + if(ppu.requestEndFrame){ + ppu.nmiCounter--; + if(ppu.nmiCounter == 0){ + ppu.requestEndFrame = false; + ppu.startVBlank(); + break FRAMELOOP; + } + } + + ppu.curX++; + if(ppu.curX==341){ + ppu.curX = 0; + ppu.endScanline(); + } + + } + } + if (this.limitFrames) { + if (this.lastFrameTime) { + while ((new Date()).getTime() - this.lastFrameTime < this.frameTime) { + // twiddle thumbs + } + } + } + this.fpsFrameCount++; + this.lastFrameTime = (new Date()).getTime(); + }, + + printFps: function() { + var now = (new Date()).getTime(); + var s = 'Running'; + if (this.lastFpsTime) { + s += ': '+(this.fpsFrameCount/((now-this.lastFpsTime)/1000)).toFixed(2)+' FPS'; + } + $("#status").text(s); + this.fpsFrameCount = 0; + this.lastFpsTime = now; + }, + + stop: function() { + //$("#status").text("Stopped."); + clearInterval(this.frameInterval); + clearInterval(this.fpsInterval); + this.isRunning = false; + }, + + reloadRom: function() { + if(this.romFile != null){ + this.loadRom(this.romFile); + } + }, + + // Loads a ROM file into the CPU and PPU. + // The ROM file is validated first. + loadRom: function(file){ + // Can't load ROM while still running. + if(this.isRunning) + this.stop(); + + $("#status").text("Loading "+file); + + // Load ROM file: + this.rom = new NES.ROM(this); + this.rom.load(file); + if(this.rom.valid){ + + // The CPU will load + // the ROM into the CPU + // and PPU memory. + + this.reset(); + + this.mmap = this.rom.createMapper(); + if (!this.mmap) return; + this.mmap.loadROM(); + this.ppu.setMirroring(this.rom.getMirroringType()); + this.romFile = file; + + $("#status").text(file+" successfully loaded. Ready to be started."); + } + else { + $("#status").text(file+" is an invalid ROM!"); + } + return this.rom.valid; + }, + + resetFps: function() { + this.lastFpsTime = null; + this.fpsFrameCount = 0; + }, + + setFramerate: function(rate){ + this.nes.opts.preferredFrameRate = rate; + this.nes.frameTime = 1000/rate; + papu.setSampleRate(this.opts.sampleRate, false); + }, + + setLimitFrames: function(limit) { + this.limitFrames = limit; + this.lastFrameTime = null; + } +} |