feat: schedule audio sampling on scheduler
DMA sound in games like Pokemon Emerald, Chobits, Love Hina, and Kirby: Nightmare in Dream Land sound great save for conerns about resampling
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92cabd248b
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172a59aefb
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@ -41,7 +41,7 @@ pub fn init(alloc: Allocator, sched: *Scheduler, paths: FilePaths) !Self {
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.pak = try GamePak.init(alloc, paths.rom, paths.save),
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.bios = try Bios.init(alloc, paths.bios),
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.ppu = try Ppu.init(alloc, sched),
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.apu = Apu.init(),
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.apu = Apu.init(sched),
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.iwram = try Iwram.init(alloc),
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.ewram = try Ewram.init(alloc),
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.dma = DmaControllers.init(),
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100
src/apu.zig
100
src/apu.zig
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@ -1,7 +1,9 @@
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const std = @import("std");
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const SDL = @import("sdl2");
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const io = @import("bus/io.zig");
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const Arm7tdmi = @import("cpu.zig").Arm7tdmi;
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const Scheduler = @import("scheduler.zig").Scheduler;
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const SoundFifo = std.fifo.LinearFifo(u8, .{ .Static = 0x20 });
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const AudioDeviceId = SDL.SDL_AudioDeviceID;
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@ -9,6 +11,9 @@ const AudioDeviceId = SDL.SDL_AudioDeviceID;
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const intToBytes = @import("util.zig").intToBytes;
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const log = std.log.scoped(.APU);
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const sample_rate = 32768;
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const sample_ticks = 280896 * 60 / sample_rate;
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pub const Apu = struct {
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const Self = @This();
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@ -25,9 +30,10 @@ pub const Apu = struct {
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cnt: io.SoundControl,
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dev: ?AudioDeviceId,
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sched: *Scheduler,
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pub fn init() Self {
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return .{
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pub fn init(sched: *Scheduler) Self {
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const apu: Self = .{
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.ch1 = ToneSweep.init(),
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.ch2 = Tone.init(),
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.ch3 = Wave.init(),
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@ -41,7 +47,11 @@ pub const Apu = struct {
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.bias = .{ .raw = 0x0200 },
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.dev = null,
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.sched = sched,
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};
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sched.push(.SampleAudio, sched.now() + sample_ticks);
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return apu;
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}
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pub fn attachAudioDevice(self: *Self, dev: AudioDeviceId) void {
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@ -53,8 +63,8 @@ pub const Apu = struct {
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// Reinitializing instead of resetting is fine because
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// the FIFOs I'm using are stack allocated and 0x20 bytes big
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if (new.sa_reset.read()) self.chA.fifo = SoundFifo.init();
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if (new.sb_reset.read()) self.chB.fifo = SoundFifo.init();
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if (new.chA_reset.read()) self.chA.fifo = SoundFifo.init();
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if (new.chB_reset.read()) self.chB.fifo = SoundFifo.init();
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self.dma_cnt = new;
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}
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@ -75,19 +85,35 @@ pub const Apu = struct {
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self.bias.raw = (@as(u16, byte) << 8) | (self.bias.raw & 0xFF);
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}
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pub fn handleTimerOverflow(self: *Self, kind: DmaSoundKind, cpu: *Arm7tdmi) void {
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pub fn sampleAudio(self: *Self, late: u64) void {
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const chA = if (self.dma_cnt.chA_vol.read()) self.chA.amplitude() else self.chA.amplitude() / 2;
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const chA_left = if (self.dma_cnt.chA_left.read()) chA else 0;
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const chA_right = if (self.dma_cnt.chA_right.read()) chA else 0;
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const chB = if (self.dma_cnt.chB_vol.read()) self.chB.amplitude() else self.chB.amplitude() / 2;
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const chB_left = if (self.dma_cnt.chB_left.read()) chB else 0;
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const chB_right = if (self.dma_cnt.chB_right.read()) chB else 0;
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const left = (chA_left + chB_left) / 2;
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const right = (chA_right + chB_right) / 2;
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if (self.dev) |dev| _ = SDL.SDL_QueueAudio(dev, &[2]f32{ left, right }, 2 * @sizeOf(f32));
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self.sched.push(.SampleAudio, self.sched.now() + sample_ticks - late);
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}
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pub fn handleTimerOverflow(self: *Self, cpu: *Arm7tdmi, tim_id: u3) void {
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if (!self.cnt.apu_enable.read()) return;
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const samples = switch (kind) {
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.A => blk: {
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break :blk self.chA.handleTimerOverflow(cpu, self.dma_cnt);
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},
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.B => blk: {
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break :blk self.chB.handleTimerOverflow(cpu, self.dma_cnt);
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},
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};
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if (@boolToInt(self.dma_cnt.chA_timer.read()) == tim_id) {
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self.chA.updateSample();
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if (self.chA.len() <= 15) cpu.bus.dma._1.enableSoundDma(0x0400_00A0);
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}
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if (self.dev) |dev| _ = SDL.SDL_QueueAudio(dev, &samples, 2);
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if (@boolToInt(self.dma_cnt.chB_timer.read()) == tim_id) {
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self.chB.updateSample();
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if (self.chB.len() <= 15) cpu.bus.dma._2.enableSoundDma(0x0400_00A4);
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}
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}
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};
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@ -207,55 +233,31 @@ pub fn DmaSound(comptime kind: DmaSoundKind) type {
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const Self = @This();
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fifo: SoundFifo,
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kind: DmaSoundKind,
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sample: i8,
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fn init() Self {
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return .{ .fifo = SoundFifo.init(), .kind = kind };
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return .{
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.fifo = SoundFifo.init(),
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.kind = kind,
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.sample = 0,
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};
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}
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pub fn push(self: *Self, value: u32) void {
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self.fifo.write(&intToBytes(u32, value)) catch {};
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}
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pub fn pop(self: *Self) u8 {
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return self.fifo.readItem() orelse 0;
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}
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pub fn len(self: *const Self) usize {
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return self.fifo.readableLength();
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}
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pub fn handleTimerOverflow(self: *Self, cpu: *Arm7tdmi, cnt: io.DmaSoundControl) [2]u8 {
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const sample = self.pop();
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pub fn updateSample(self: *Self) void {
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if (self.fifo.readItem()) |sample| self.sample = @bitCast(i8, sample);
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}
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var left: u8 = 0;
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var right: u8 = 0;
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var fifo_addr: u32 = undefined;
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switch (kind) {
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.A => {
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const vol = @boolToInt(!cnt.sa_vol.read()); // if unset, vol is 50%
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if (cnt.sa_left_enable.read()) left = sample >> vol;
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if (cnt.sa_right_enable.read()) right = sample >> vol;
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fifo_addr = 0x0400_00A0;
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},
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.B => {
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const vol = @boolToInt(!cnt.sb_vol.read()); // if unset, vol is 50%
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if (cnt.sb_left_enable.read()) left = sample >> vol;
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if (cnt.sb_right_enable.read()) right = sample >> vol;
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fifo_addr = 0x0400_00A4;
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},
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}
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if (self.len() <= 15) {
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cpu.bus.dma._1.enableSoundDma(fifo_addr);
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cpu.bus.dma._2.enableSoundDma(fifo_addr);
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}
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return .{ left, right };
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pub fn amplitude(self: *const Self) f32 {
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return @intToFloat(f32, self.sample) / 127.5 - (1 / 255);
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}
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};
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}
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@ -595,20 +595,20 @@ pub const ChannelVolumeControl = extern union {
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/// Read / Write
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pub const DmaSoundControl = extern union {
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ch_vol: Bitfield(u16, 0, 2),
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sa_vol: Bit(u16, 2),
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sb_vol: Bit(u16, 3),
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chA_vol: Bit(u16, 2),
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chB_vol: Bit(u16, 3),
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sa_right_enable: Bit(u16, 8),
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sa_left_enable: Bit(u16, 9),
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sa_timer: Bit(u16, 10),
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chA_right: Bit(u16, 8),
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chA_left: Bit(u16, 9),
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chA_timer: Bit(u16, 10),
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/// Write only?
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sa_reset: Bit(u16, 11),
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chA_reset: Bit(u16, 11),
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sb_right_enable: Bit(u16, 12),
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sb_left_enable: Bit(u16, 13),
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sb_timer: Bit(u16, 14),
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chB_right: Bit(u16, 12),
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chB_left: Bit(u16, 13),
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chB_timer: Bit(u16, 14),
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/// Write only?
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sb_reset: Bit(u16, 15),
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chB_reset: Bit(u16, 15),
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raw: u16,
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};
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@ -109,13 +109,7 @@ fn Timer(comptime id: u2) type {
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// DMA Sound Things
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if (id == 0 or id == 1) {
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const apu = &cpu.bus.apu;
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const a_tim = @boolToInt(apu.dma_cnt.sa_timer.read());
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const b_tim = @boolToInt(apu.dma_cnt.sb_timer.read());
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if (a_tim == id) apu.handleTimerOverflow(.A, cpu);
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if (b_tim == id) apu.handleTimerOverflow(.B, cpu);
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cpu.bus.apu.handleTimerOverflow(cpu, id);
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}
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// Perform Cascade Behaviour
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@ -242,9 +242,9 @@ fn initAudio() SDL.SDL_AudioDeviceID {
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var have: SDL.SDL_AudioSpec = undefined;
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var want = std.mem.zeroes(SDL.SDL_AudioSpec);
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want.freq = 32768;
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want.format = SDL.AUDIO_S8;
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want.format = SDL.AUDIO_F32;
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want.channels = 2;
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want.samples = 0x200;
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want.samples = 0x100;
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want.callback = null;
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const dev = SDL.SDL_OpenAudioDevice(null, 0, &want, &have, 0);
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@ -51,6 +51,7 @@ pub const Scheduler = struct {
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3 => cpu.bus.tim._3.handleOverflow(cpu, late),
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}
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},
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.SampleAudio => cpu.bus.apu.sampleAudio(late),
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.HBlank => cpu.bus.ppu.handleHBlankEnd(cpu, late), // The end of a HBlank
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.VBlank => cpu.bus.ppu.handleHDrawEnd(cpu, late), // The end of a VBlank
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}
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@ -102,4 +103,5 @@ pub const EventKind = union(enum) {
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VBlank,
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Draw,
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TimerOverflow: u2,
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SampleAudio,
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};
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