zx-generation/dist/audio-worklet.js

A high-fidelity ZX Spectrum emulator in JavaScript — fully generated by a large language model (LLM) to explore the boundaries of AI in systems programming.

class e{static T_STATES_PER_FRAME=69888;static FRAMES_PER_SECOND=50;static CPU_FREQ=e.T_STATES_PER_FRAME*e.FRAMES_PER_SECOND;static MAX_EDGES_PER_FRAME=2048;constructor(){this.audioContext=null,this.workletNode=null,this.compressor=null,this.gainNode=null,this.edgePool=Array.from({length:4},(()=>new Float64Array(2*e.MAX_EDGES_PER_FRAME))),this.currentLevel=0,this.frameEdges=[],this.totalTStates=0,this.frameCount=0,this.edgeCountTot=0,this.volume=.5,this.enabled=!1,this.resumeButton=null,this.debugMode=!1}async init(){if(this.audioContext)return this.enabled;try{this.audioContext=new(window.AudioContext||window.webkitAudioContext)({latencyHint:"interactive",sampleRate:48e3}),this.audioContext.addEventListener("statechange",(()=>this.#e()));const e=this.audioContext.sampleRate,t=this.#t(e),s=URL.createObjectURL(new Blob([t],{type:"application/javascript"}));return await this.audioContext.audioWorklet.addModule(s),URL.revokeObjectURL(s),this.workletNode=new AudioWorkletNode(this.audioContext,"zx-beeper"),this.workletNode.port.onmessage=e=>{e.data?.returnBuffer instanceof ArrayBuffer&&this.edgePool.push(new Float64Array(e.data.returnBuffer))},this.compressor=this.audioContext.createDynamicsCompressor(),this.compressor.threshold.value=-12,this.compressor.knee.value=2,this.compressor.ratio.value=2,this.compressor.attack.value=.001,this.compressor.release.value=.1,this.gainNode=this.audioContext.createGain(),this.gainNode.gain.value=0,this.workletNode.connect(this.compressor),this.compressor.connect(this.gainNode),this.gainNode.connect(this.audioContext.destination),this.gainNode.gain.setValueAtTime(0,this.audioContext.currentTime),this.gainNode.gain.linearRampToValueAtTime(this.volume,this.audioContext.currentTime+.1),"suspended"===this.audioContext.state&&this.#s(),this.enabled=!0,!0}catch(e){return console.error("AudioWorklet init failed:",e),this.enabled=!1,!1}}setBeeperState(e,t){if(!this.enabled)return;const s=.9*(16&e?1:0)+.33*(8&e?0:1);s!==this.currentLevel&&(this.frameEdges.push({tState:t,level:s}),this.currentLevel=s,++this.edgeCountTot)}startFrame(){this.frameEdges=[{tState:0,level:this.currentLevel}]}endFrame(t){if(!this.enabled||!this.workletNode)return;this.totalTStates+=t,++this.frameCount;const s=this.edgePool.pop()||new Float64Array(2*e.MAX_EDGES_PER_FRAME),n=Math.min(this.frameEdges.length,e.MAX_EDGES_PER_FRAME);for(let e=0;e<n;++e){const t=this.frameEdges[e];s[2*e]=t.tState,s[2*e+1]=t.level}this.workletNode.port.postMessage({frame:!0,edges:s,edgeCount:n,frameTStates:t,syncTState:this.totalTStates},[s.buffer])}reset(){this.enabled&&(this.gainNode?.gain.linearRampToValueAtTime(0,this.audioContext.currentTime+.02),this.currentLevel=0,this.frameEdges=[],this.totalTStates=0,this.frameCount=0,this.edgeCountTot=0,this.workletNode?.port.postMessage({reset:!0}),setTimeout((()=>{this.gainNode?.gain.linearRampToValueAtTime(this.volume,this.audioContext.currentTime+.05)}),30))}setVolume(e){this.volume=Math.max(0,Math.min(1,e)),this.gainNode&&this.gainNode.gain.exponentialRampToValueAtTime(Math.max(1e-4,this.volume),this.audioContext.currentTime+.1)}setMuted(e){this.setVolume(e?0:this.volume)}setDebugMode(e){this.debugMode=!!e}isReady(){return this.enabled&&"running"===this.audioContext?.state}getStats(){return{enabled:this.enabled,contextState:this.audioContext?this.audioContext.state:"closed",sampleRate:this.audioContext?this.audioContext.sampleRate:0,totalTStates:this.totalTStates,frameCount:this.frameCount,totalEdges:this.edgeCountTot,bufferSize:e.MAX_EDGES_PER_FRAME,volume:this.volume}}async stop(){this.enabled&&(this.enabled=!1,this.gainNode?.gain.linearRampToValueAtTime(0,this.audioContext.currentTime+.05),await new Promise((e=>setTimeout(e,60))),this.workletNode?.disconnect(),this.compressor?.disconnect(),this.gainNode?.disconnect(),await(this.audioContext?.close()),this.workletNode=this.compressor=this.gainNode=this.audioContext=null,this.resumeButton?.remove(),this.resumeButton=null)}#t(e){return`\n            class ZXBeeperProcessor extends AudioWorkletProcessor {\n                static T_STATES_PER_FRAME = 69888;\n                static FRAMES_PER_SECOND  = 50;\n                static CPU_FREQ = ZXBeeperProcessor.T_STATES_PER_FRAME *\n                                   ZXBeeperProcessor.FRAMES_PER_SECOND;\n\n                constructor () {\n                    super();\n                    this.sr = ${e};                              // fixed\n                    this.tStatesPerSample =\n                        ZXBeeperProcessor.CPU_FREQ / this.sr;\n                    this.samplesPerFrame =\n                        Math.round(this.sr / ZXBeeperProcessor.FRAMES_PER_SECOND);\n\n                    /* Edge data -------------------------------------- */\n                    this.edgeBuf      = null;\n                    this.edgeCount    = 0;\n\n                    /* Synth state ----------------------------------- */\n                    this.currentLevel    = 0;\n                    this.generatorTState = 0;      // absolute\n\n                    /* Filters: 3.5 kHz low-pass + DC blocker -------- */\n                    const fc = 3500;\n                    this.lpAlpha =\n                        1 - Math.exp(-2 * Math.PI * fc / this.sr);\n                    this.lpState   = 0;\n                    this.dcCoeff   = 0.9995;\n                    this.dcPrevIn  = 0;\n                    this.dcPrevOut = 0;\n\n                    /* Frame buffer ---------------------------------- */\n                    this.frameBuf   =\n                        new Float32Array(this.samplesPerFrame + 128);\n                    this.fbPos      = 0;\n                    this.frameReady = false;\n\n                    this.port.onmessage = e => this.#onMessage(e.data);\n                }\n\n                /* ------------------ messages ---------------------- */\n                #onMessage (d) {\n                    if (d.frame) {\n                        this.edgeBuf      = new Float64Array(d.edges);\n                        this.edgeCount    = d.edgeCount | 0;\n                        this.frameTStates = d.frameTStates | 0;\n                        this.syncTState   = d.syncTState | 0;\n\n                        this.#renderFrame();\n                        this.frameReady = true;\n\n                    } else if (d.reset) {\n                        this.currentLevel = 0;\n                        this.lpState      = 0;\n                        this.dcPrevIn     = 0;\n                        this.dcPrevOut    = 0;\n                        this.fbPos        = 0;\n                        this.frameReady   = false;\n                        this.generatorTState = 0;\n                    }\n                }\n\n                /* -------------- render single 20 ms frame ---------- */\n                #renderFrame () {\n                    const N = this.samplesPerFrame;\n                    let eix = 0;\n\n                    for (let s = 0; s < N; ++s) {\n                        const relTS = s * this.tStatesPerSample;\n                        while (eix < this.edgeCount &&\n                               this.edgeBuf[eix * 2] <= relTS) {\n                            this.currentLevel = this.edgeBuf[eix * 2 + 1];\n                            ++eix;\n                        }\n\n                        /* low-pass */\n                        this.lpState += this.lpAlpha *\n                                        (this.currentLevel - this.lpState);\n\n                        /* bipolar + DC-block */\n                        const bb  = (this.lpState - 0.5) * 2;\n                        const out = bb - this.dcPrevIn +\n                                    this.dcCoeff * this.dcPrevOut;\n                        this.dcPrevIn  = bb;\n                        this.dcPrevOut = out;\n\n                        this.frameBuf[s] = out * 0.6;\n                    }\n\n                    /* advance generator clock & PLL correction */\n                    this.generatorTState += N * this.tStatesPerSample;\n                    const drift = this.syncTState - this.generatorTState;\n                    this.generatorTState += drift * 0.05;        // 5 % pull\n\n                    this.fbPos = 0;\n\n                    /* return buffer for reuse */\n                    this.port.postMessage({ returnBuffer: this.edgeBuf.buffer },\n                                          [this.edgeBuf.buffer]);\n                    this.edgeBuf = null;\n                    this.edgeCount = 0;\n                }\n\n                /* ---------------- audio callback ------------------ */\n                process (_in, out) {\n                    const ch = out[0][0];\n                    if (!ch) return true;\n\n                    for (let i = 0, n = ch.length; i < n; ++i) {\n                        if (this.frameReady && this.fbPos < this.samplesPerFrame) {\n                            ch[i] = this.frameBuf[this.fbPos++];\n                        } else {\n                            /* hold last sample to avoid clicks */\n                            ch[i] = this.fbPos ? this.frameBuf[this.fbPos - 1] : 0;\n                        }\n                        if (this.fbPos >= this.samplesPerFrame) {\n                            this.frameReady = false;\n                            this.fbPos = 0;\n                        }\n                    }\n                    return true;\n                }\n            }\n            registerProcessor("zx-beeper", ZXBeeperProcessor);\n        `}#s(){}#e(){}}export{e as SpectrumAudioWorklet};