Add sampling capability to square wave channels

jsnes/src/index.js

@@ -1,4 +1,5 @@
 module.exports = {
   Controller: require("./controller"),
   NES: require("./nes"),
+  Sample: require("./sample"),
 };

jsnes/src/papu.js

@@ -316,23 +316,31 @@ PAPU.prototype = {
     }
 
     // Clock Square channel 1 Prog timer:
+    var square1sample = this.nes.opts[square1.sampleName];
     square1.progTimerCount -= nCycles;
     if (square1.progTimerCount <= 0) {
       square1.progTimerCount += (square1.progTimerMax + 1) << 1;
+      if (square1sample) { square1sample.advance(4); }
 
       square1.squareCounter++;
       square1.squareCounter &= 0x7;
       square1.updateSampleValue();
+    } else if (square1sample) {
+      square1.updateSampleValue();
     }
 
     // Clock Square channel 2 Prog timer:
+    var square2sample = this.nes.opts[square2.sampleName];
     square2.progTimerCount -= nCycles;
     if (square2.progTimerCount <= 0) {
       square2.progTimerCount += (square2.progTimerMax + 1) << 1;
+      if (square2sample) { square2sample.advance(4); }
 
       square2.squareCounter++;
       square2.squareCounter &= 0x7;
       square2.updateSampleValue();
+    } else if (square2sample) {
+      square2.updateSampleValue();
     }
 
     // Clock noise channel Prog timer:
@@ -499,6 +507,9 @@ PAPU.prototype = {
     this.noise.accValue = smpNoise >> 4;
     this.noise.accCount = 1;
 
+    var extra = 0;
+    if (this.nes.opts.sampleSquare1) { this.smpSquare1 = 0; extra += this.square1.sampleValue; }
+    if (this.nes.opts.sampleSquare2) { this.smpSquare2 = 0; extra += this.square2.sampleValue; }
     // Stereo sound.
 
     // Left channel:
@@ -560,7 +571,7 @@ PAPU.prototype = {
     }
 
     if (this.nes.opts.onAudioSample) {
-      this.nes.opts.onAudioSample(sampleValueL / 32768, sampleValueR / 32768);
+      this.nes.opts.onAudioSample((sampleValueL / 32768) + extra, (sampleValueR / 32768) + extra);
     }
 
     // Reset sampled values:
@@ -1156,6 +1167,7 @@ ChannelNoise.prototype = {
 
 var ChannelSquare = function (papu, square1) {
   this.papu = papu;
+  this.sampleName = `sampleSquare${square1 ? 1 : 2}`;
 
   // prettier-ignore
   this.dutyLookup = [
@@ -1292,6 +1304,7 @@ ChannelSquare.prototype = {
   },
 
   updateSampleValue: function () {
+    var sample = this.papu.nes.opts[this.sampleName];
     if (this.isEnabled && this.lengthCounter > 0 && this.progTimerMax > 7) {
       if (
         this.sweepMode === 0 &&
@@ -1299,13 +1312,25 @@ ChannelSquare.prototype = {
       ) {
         //if (this.sweepCarry) {
         this.sampleValue = 0;
+        if (sample) { sample.reset(); }
+      } else {
+        if (sample) {
+          if (this.envVolume === 0 || this.masterVolume === 0) {
+            this.sampleValue = 0;
+            sample.reset();
+          } else {
+            this.sampleValue = sample.sample(this.progTimerCount, (this.progTimerMax + 1) << 1, this.masterVolume);
+            // console.log("sampled value:", this.sampleValue);
+          }
         } else {
           this.sampleValue =
             this.masterVolume *
             this.dutyLookup[(this.dutyMode << 3) + this.squareCounter];
         }
+      }
     } else {
       this.sampleValue = 0;
+      if (sample) { sample.reset(); }
     }
   },
 

jsnes/src/sample.js

@@ -0,0 +1,52 @@
+
+var Sample = function (audiobuffer, toneHz, gain) {
+  var samples = new Float32Array(audiobuffer.getChannelData(0));
+  for (var chan = 1; chan < audiobuffer.numberOfChannels; chan ++) {
+    var channel_samples = audiobuffer.getChannelData(chan);
+    for (var i = 0; i < samples.length; i ++) {
+      samples[i] += channel_samples[i] + 1;
+    }
+  }
+  gain = (gain ? gain : 1) / (audiobuffer.numberOfChannels * 2);
+  for (i = 0; i < samples.length; i ++) {
+    samples[i] = samples[i] * gain;
+  }
+
+  this.samples = samples;
+  this.index = 0;
+  this.increment = audiobuffer.sampleRate / toneHz;
+  this.prevMaxTimer = null;
+  this.clocksPerPeriod = 1;
+}
+
+Sample.prototype = {
+  clone: function() {
+    var copy = Object.create(this);
+    copy.index = 0;
+    return copy;
+  },
+  advance: function(clocksPerPeriod) { 
+    this.clocksPerPeriod = clocksPerPeriod;
+    this.index += this.increment / clocksPerPeriod; 
+  },
+  reset: function() { this.index = 0; },
+  sample: function(timer, maxTimer, volume) {
+    if (maxTimer !== this.prevMaxTimer) {
+      if (this.prevMaxTimer) {
+        var semitoneInterval = 1.059463;
+        const semitoneUp = this.prevMaxTimer * semitoneInterval;
+        const semitoneDown = this.prevMaxTimer / semitoneInterval;
+        if (maxTimer <= semitoneDown || maxTimer >= semitoneUp) {
+          this.index = 0;
+        }
+      }
+      this.prevMaxTimer = maxTimer;
+    }
+    var index = (this.index + (((this.increment / this.clocksPerPeriod) * (maxTimer - timer)) / maxTimer)) >> 0;
+    if (index < 0) index = 0;
+    if (index >= this.samples.length) index = this.samples.length - 1;
+    return (this.samples[index] * volume);
+  }
+}
+
+module.exports = Sample;

package.json

@@ -6,10 +6,11 @@
   "scripts": {
     "dev": "vite",
     "build": "vite build",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "rebuild": "cd jsnes && yarn && cd .. && yarn upgrade jsnes && vite --force"
   },
   "dependencies": {
-    "jsnes": "file:../jsnes"
+    "jsnes": "file:./jsnes"
   },
   "devDependencies": {
     "@sveltejs/vite-plugin-svelte": "^4.0.0",

src/App.svelte

@@ -1,7 +1,9 @@
 <script>
+  import { loadSample } from './lib/sampload.js'
   import NES from './lib/NES.svelte'
 
   let rom = $state(null);
+  let opts = $state({});
 
   function nes_load_url(url) {
     // todo: port to fetch
@@ -21,12 +23,23 @@
     };
     req.send();
   }
-
+  async function meow() {
+    const sample = await loadSample("samples/meow1.wav", 1400, 5);
+    opts = { sampleSquare1: sample, sampleSquare2: sample.clone() };
+  }
+  async function yeargh() {
+    const sample = await loadSample("samples/YEARGH.WAV", 1400, 1);
+    opts = { sampleSquare1: sample, sampleSquare2: sample.clone() };
+  }
 </script>
 
 <main>
-  <NES {rom}/>
-  <button onclick={() => nes_load_url("smb.nes")}>Start!</button>
+  <NES {rom} {opts}/>
+  <button onclick={() => nes_load_url("smb.nes")}>Mario</button>
+  <button onclick={() => nes_load_url("Tetris.nes")}>Tetris</button>
+  <button onclick={() => { opts = {} }}>Normal</button>
+  <button onclick={meow}>Meow</button>
+  <button onclick={yeargh}>Yeargh</button>
   <p>DPad: Arrow keys<br/>B button: Z, A button: X, Select: Tab / C, Start: Return / V</p>
 </main>
 

src/lib/NES.svelte

@@ -3,7 +3,7 @@
     import { onMount } from 'svelte';
 
     let nes = $state();
-    let { rom } = $props();
+    let { rom, opts } = $props();
 
     const SCREEN_WIDTH = 256;
     const SCREEN_HEIGHT = 240;
@@ -81,10 +81,10 @@
         }
 
         let emu = new jsnes.NES({
-            onFrame: function(framebuffer_24){
+            onFrame: function(framebuffer_24) {
                 for(var i = 0; i < FRAMEBUFFER_SIZE; i++) framebuffer_u32[i] = 0xFF000000 | framebuffer_24[i];
             },
-            onAudioSample: function(l, r){
+            onAudioSample: function(l, r) {
                 audio_samples_L[audio_write_cursor] = l;
                 audio_samples_R[audio_write_cursor] = r;
                 audio_write_cursor = (audio_write_cursor + 1) & SAMPLE_MASK;
@@ -105,6 +105,7 @@
             canvas_ctx.putImageData(image, 0, 0);
         }
         nes = {
+            baseOpts: emu.opts,
             emu,
             activate() {
                 this.stopAnimating();
@@ -140,6 +141,11 @@
             }
         }
     })
+    $effect(() => {
+        if (nes) {
+            nes.emu.opts = { ...opts, ...nes.baseOpts };
+        }
+    })
 </script>
 
 <main>

src/lib/sampload.js

@@ -0,0 +1,8 @@
+import { Sample } from 'jsnes';
+
+export async function loadSample(url, toneHz, gain) {
+    const audioCtx = new AudioContext();
+    const response = await fetch(url);
+    const buffer = await audioCtx.decodeAudioData(await response.arrayBuffer());
+    return new Sample(buffer, toneHz, gain);
+}

yarn.lock

@@ -357,7 +357,7 @@ is-reference@^3.0.3:
   dependencies:
     "@types/estree" "^1.0.6"
 
-"jsnes@file:../jsnes":
+"jsnes@file:./jsnes":
   version "1.2.1"
 
 kleur@^4.1.5: