Nearing a solution

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_BATTERY_LEVEL = 0x1e;
-export const ADDR_FRAMEBUFFER = 0x1e;
+export const ADDR_FRAMEBUFFER = 0x20;
 export const ADDR_AUDIO_BUFFER = 0xa020;
 
 export const CONTROLS_START = 1;

src/badge.zig

@@ -216,7 +216,7 @@ pub fn main() !void {
     });
 
     timer.init();
-    audio.init(&cart.call_audio);
+    audio.init();
 
     // Light sensor adc
     microzig.board.A6_LIGHT.set_mux(.B);
@@ -254,6 +254,14 @@ pub fn main() !void {
 
         cart.tick();
 
+        if (!audio.audio_ready) {
+            // microzig.cpu.disable_interrupts();
+            // defer microzig.cpu.enable_interrupts();
+
+            cart.call_audio();
+            audio.audio_ready = true;
+        }
+
         var pixels: [5]board.NeopixelColor = undefined;
         for (&pixels, cart.api.neopixels) |*local, pixel|
             local.* = .{

src/badge/cart.zig

@@ -20,23 +20,23 @@ const libcart = struct {
     extern fn audio() void;
 
     export fn __return_thunk__() linksection(".text.cart") noreturn {
-        asm volatile (" svc #12");
+        asm volatile (" svc #11");
         unreachable;
     }
 };
 
 pub fn svcall_handler() callconv(.Naked) void {
     asm volatile (
         \\ mvns r0, lr, lsl #31 - 2
-        \\ bcc 12f
+        \\ bcc 11f
         \\ ite mi
         \\ movmi r1, sp
         \\ mrspl r1, psp
         \\ ldr r2, [r1, #6 * 4]
         \\ subs r2, #2
         \\ ldrb r3, [r2, #1 * 1]
         \\ cmp r3, #0xDF
-        \\ bne 12f
+        \\ bne 11f
         \\ ldrb r3, [r2, #0 * 1]
         \\ cmp r3, #11
         \\ bhi 12f
@@ -168,7 +168,7 @@ fn call(func: *const fn () callconv(.C) void) void {
     frame[7] = 1 << 24;
     asm volatile (
         \\ msr psp, %[process_stack]
-        \\ svc #12
+        \\ svc #11
         :
         : [process_stack] "r" (frame.ptr),
         : "r0", "r1", "r2", "r3", "memory"
@@ -191,7 +191,7 @@ fn call(func: *const fn () callconv(.C) void) void {
 }
 
 pub fn call_audio() void {
-    call(libcart.audio);
+    call(&libcart.audio);
 }
 
 fn User(comptime T: type) type {

src/badge/feature_test.zig

@@ -158,12 +158,12 @@ export fn update() void {
 var wave_t: f32 = 0;
 
 export fn audio() void {
-    // for (&cart.audio_buffer[0], &cart.audio_buffer[1]) |*l, *r| {
-    //     const val: i16 = @intFromFloat(@sin(wave_t) * std.math.maxInt(i16));
+    for (&cart.audio_buffer[0], &cart.audio_buffer[1]) |*l, *r| {
+        const val: i16 = @intFromFloat(@sin(wave_t) * std.math.maxInt(i16));
 
-    //     l.* = val;
-    //     r.* = val;
+        l.* = val;
+        r.* = val;
 
-    //     wave_t += 0.1;
-    // }
+        wave_t += 0.1;
+    }
 }

src/board/audio.zig

@@ -1,9 +1,8 @@
+pub var audio_ready = false;
 pub const sample_buffer: *volatile [2][512]i16 = @ptrFromInt(0x20000000 + 0xa020);
-var call_audio: ?*const fn () void = null;
 
-pub fn init(call_audio_fn: *const fn () void) void {
+pub fn init() void {
     @setCold(true);
-    call_audio = call_audio_fn;
 
     board.A0_SPKR.set_dir(.out);
     board.A1_VCC.set_dir(.in);
@@ -185,16 +184,17 @@ pub fn init(call_audio_fn: *const fn () void) void {
 }
 
 pub fn mix() callconv(.C) void {
-    // var speaker_enable: port.Level = .low;
-    const speaker_enable: port.Level = .low;
+    var speaker_enable: port.Level = .low;
 
-    // if (call_audio) |ca| ca();
+    if (audio_ready) {
+        for (&sample_buffer[
+            (dma.get_audio_part() + sample_buffer.len - 1) % sample_buffer.len
+        ]) |sample| {
+            if (sample != 0) speaker_enable = .high;
+        }
 
-    // for (&sample_buffer[
-    //     (dma.get_audio_part() + sample_buffer.len - 1) % sample_buffer.len
-    // ]) |sample| {
-    //     if (sample != 0) speaker_enable = .high;
-    // }
+        audio_ready = false;
+    }
 
     board.SPKR_EN.write(speaker_enable);
     dma.ack_audio();

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]i16) bool {}`
+//! - `export fn audio() void {}`
 
 const std = @import("std");
 const builtin = @import("builtin");
@@ -86,7 +86,7 @@ pub const neopixels: *[5]NeopixelColor = @ptrFromInt(base + 0x08);
 pub const red_led: *bool = @ptrFromInt(base + 0x1c);
 pub const battery_level: *u12 = @ptrFromInt(base + 0x1e);
 pub const framebuffer: *volatile [screen_width][screen_height]Pixel = @ptrFromInt(base + 0x20);
-// pub const audio_buffer: *volatile [2][512]i16 = @ptrFromInt(base + 0xa020);
+pub const audio_buffer: *volatile [2][512]i16 = @ptrFromInt(base + 0xa020);
 
 pub const BlitOptions = struct {
     pub const Flags = packed struct(u32) {