Works but slow and crunch

PCM test file not included for copyright reasons

build.zig

@@ -144,7 +144,7 @@ pub const Cart = struct {
 
     pub fn install_with_watcher(c: *const Cart, d: *Build.Dependency, b: *Build, opt: CartWatcherOptions) *Build.Step.Run {
         if (opt.build_firmware) {
-            c.mz.install_firmware(b, c.fw, .{ .format = .{ .uf2 = .SAMD51 } });
+            // c.mz.install_firmware(b, c.fw, .{ .format = .{ .uf2 = .SAMD51 } });
         }
         const install_artifact_step = b.addInstallArtifact(c.wasm, .{});
         b.getInstallStep().dependOn(&install_artifact_step.step);
@@ -196,7 +196,7 @@ pub fn add_cart(
     wasm.initial_memory = 64 * 65536;
     wasm.max_memory = 64 * 65536;
     wasm.stack_size = 14752;
-    wasm.global_base = 2 * 512 * 2 + 0xa01e;
+    wasm.global_base = 100_000;
 
     wasm.rdynamic = true;
     wasm.root_module.addImport("cart-api", d.module("cart-api"));

simulator/src/apu.ts

@@ -24,6 +24,7 @@ export class APU {
     }
 
     send(left: number[], right: number[]) {
+        console.log(left, right);
         this.processorPort!.postMessage({left, right});
     }
 

simulator/src/constants.ts

@@ -12,7 +12,7 @@ export const ADDR_LIGHT_LEVEL = 0x06;
 export const ADDR_NEOPIXELS = 0x08;
 export const ADDR_RED_LED = 0x1c;
 export const ADDR_FRAMEBUFFER = 0x1e;
-export const ADDR_AUDIO_BUFFER = 0xa01e;
+export const ADDR_AUDIO_BUFFER = 0xb01e;
 
 export const CONTROLS_START = 1;
 export const CONTROLS_SELECT = 2;

simulator/src/runtime.ts

@@ -223,7 +223,7 @@ export class Runtime {
             this.bluescreenOnError(start_function);
         }
 
-        new Uint16Array(this.memory.buffer).slice(constants.ADDR_AUDIO_BUFFER, constants.ADDR_AUDIO_BUFFER + 2 * 512).fill(0);
+        // new Int16Array(this.memory.buffer).slice(constants.ADDR_AUDIO_BUFFER, constants.ADDR_AUDIO_BUFFER + 2 * 512).fill(0);
     }
 
     update () {
@@ -242,10 +242,10 @@ export class Runtime {
         //     this.bluescreenOnError(audio_function);
         // }
 
-        if (audio_function(constants.ADDR_AUDIO_BUFFER, constants.ADDR_AUDIO_BUFFER + 512 * 2)) {
+        if (audio_function(constants.ADDR_AUDIO_BUFFER)) {
             this.apu.send(
-                [...new Uint16Array(this.memory.buffer).slice(constants.ADDR_AUDIO_BUFFER, constants.ADDR_AUDIO_BUFFER + 512)],
-                [...new Uint16Array(this.memory.buffer).slice(constants.ADDR_AUDIO_BUFFER + 512, constants.ADDR_AUDIO_BUFFER + 512 * 2)],
+                [...new Int16Array(this.memory.buffer.slice(constants.ADDR_AUDIO_BUFFER)).slice(0, 512)],
+                [...new Int16Array(this.memory.buffer.slice(constants.ADDR_AUDIO_BUFFER + 512 * 2)).slice(0, 512)],
             );
         }
     }

src/badge/feature_test.zig

@@ -155,14 +155,15 @@ export fn update() void {
     });
 }
 
-var off: f32 = 0;
-export fn audio(buffer: *volatile [2][512]u16) bool {
-    for (&buffer[0], &buffer[1]) |*l, *r| {
-        l.* = @intFromFloat(@sin(off) * std.math.maxInt(u16));
-        r.* = @intFromFloat(@sin(off) * std.math.maxInt(u16));
+const raw_data = std.mem.bytesAsSlice(i16, @embedFile("pepsi.raw"));
 
-        off += 0.1;
-    }
+var audio_offset: usize = 0;
+
+export fn audio(buffer: *volatile [2][512]i16) bool {
+    @memcpy(&buffer[0], raw_data[audio_offset..][0..512]);
+    @memcpy(&buffer[1], raw_data[audio_offset..][0..512]);
+
+    audio_offset += 512;
 
-    return false;
+    return true;
 }

src/cart/api.zig

@@ -3,7 +3,7 @@
 //! To get started, define the following functions:
 //! - `export fn start() void {}`
 //! - `export fn update() void {}`
-//! - `export fn audio(buffer: *volatile [2][512]u16) bool {}`
+//! - `export fn audio(buffer: *volatile [2][512]i16) bool {}`
 
 const std = @import("std");
 const builtin = @import("builtin");