parent
97a689ab55
commit
0184ec3e5e
181
src/apu.zig
181
src/apu.zig
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@ -24,7 +24,8 @@ pub const Apu = struct {
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chB: DmaSound(.B),
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bias: io.SoundBias,
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ch_vol_cnt: io.ChannelVolumeControl,
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/// NR51
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psg_cnt: io.ChannelVolumeControl,
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dma_cnt: io.DmaSoundControl,
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cnt: io.SoundControl,
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@ -33,6 +34,7 @@ pub const Apu = struct {
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sched: *Scheduler,
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fs: FrameSequencer,
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capacitor: f32,
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pub fn init(sched: *Scheduler) Self {
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const apu: Self = .{
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@ -43,7 +45,7 @@ pub const Apu = struct {
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.chA = DmaSound(.A).init(),
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.chB = DmaSound(.B).init(),
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.ch_vol_cnt = .{ .raw = 0 },
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.psg_cnt = .{ .raw = 0 },
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.dma_cnt = .{ .raw = 0 },
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.cnt = .{ .raw = 0 },
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.bias = .{ .raw = 0x0200 },
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@ -52,16 +54,22 @@ pub const Apu = struct {
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.stream = SDL.SDL_NewAudioStream(SDL.AUDIO_F32, 2, 1 << 15, SDL.AUDIO_F32, 2, host_sample_rate) orelse unreachable,
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.sched = sched,
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.capacitor = 0,
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.fs = FrameSequencer.init(),
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};
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sched.push(.SampleAudio, sched.now() + apu.sampleTicks());
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sched.push(.{ .ApuChannel = 0 }, sched.now() + SquareWave.ticks);
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sched.push(.FrameSequencer, sched.now() + ((1 << 24) / 1 << 15));
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sched.push(.FrameSequencer, sched.now() + ((1 << 24) / 512));
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return apu;
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}
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fn reset(self: *Self) void {
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self.ch1.reset();
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// TODO: Reset the rest of the channels
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}
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pub fn setDmaCnt(self: *Self, value: u16) void {
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const new: io.DmaSoundControl = .{ .raw = value };
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@ -80,11 +88,12 @@ pub const Apu = struct {
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if (value) {
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self.fs.step = 0; // Reset Frame Sequencer
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// TODO: Reset Duty position for Square channels
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// TODO: Reset Duty Position for Ch2 Square
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self.ch1.square.pos = 0;
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// TODO: Reset Channel 3 offset ptr
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} else {
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// TODO: Reset APU
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self.reset();
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}
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}
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@ -102,12 +111,12 @@ pub const Apu = struct {
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/// NR50
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pub fn setSoundCntLLow(self: *Self, byte: u8) void {
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self.ch_vol_cnt.raw = (self.ch_vol_cnt.raw & 0xFF00) | byte;
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self.psg_cnt.raw = (self.psg_cnt.raw & 0xFF00) | byte;
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}
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/// NR51
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pub fn setSoundCntLHigh(self: *Self, byte: u8) void {
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self.ch_vol_cnt.raw = @as(u16, byte) << 8 | (self.ch_vol_cnt.raw & 0xFF);
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self.psg_cnt.raw = @as(u16, byte) << 8 | (self.psg_cnt.raw & 0xFF);
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}
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pub fn setBiasHigh(self: *Self, byte: u8) void {
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@ -117,9 +126,31 @@ pub const Apu = struct {
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pub fn sampleAudio(self: *Self, late: u64) void {
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// Sample Channel 1
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const ch1_sample = self.ch1.amplitude();
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const ch1_left = if (self.ch_vol_cnt.ch1_left.read()) ch1_sample else 0;
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const ch1_right = if (self.ch_vol_cnt.ch1_right.read()) ch1_sample else 0;
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const ch1_sample = self.highPassFilter(self.ch1.amplitude(), self.ch1.enabled);
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const ch1_left = if (self.psg_cnt.ch1_left.read()) ch1_sample else 0;
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const ch1_right = if (self.psg_cnt.ch1_right.read()) ch1_sample else 0;
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const mixed_left = ch1_left;
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const mixed_right = ch1_right;
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// Apply NR50 Volume Modifications
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const nr50_left = (@intToFloat(f32, self.psg_cnt.left_vol.read()) + 1.0) * mixed_left;
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const nr50_right = (@intToFloat(f32, self.psg_cnt.right_vol.read()) + 1.0) * mixed_right;
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// Apply SOUNDCNT_H Volume Modifications
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const psg_left = switch (self.dma_cnt.ch_vol.read()) {
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0b00 => nr50_left * 0.25,
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0b01 => nr50_left * 0.5,
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0b10 => nr50_left * 0.75,
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0b11 => nr50_left, // Prohibited
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};
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const psg_right = switch (self.dma_cnt.ch_vol.read()) {
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0b00 => nr50_right * 0.25,
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0b01 => nr50_right * 0.5,
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0b10 => nr50_right * 0.75,
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0b11 => nr50_right, // Prohibited
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};
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// Sample Dma Channels
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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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@ -131,10 +162,10 @@ pub const Apu = struct {
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// const chB_right = if (self.dma_cnt.chB_right.read()) chB else 0;
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// Mix all Channels
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// const left = (chA_left + chB_left + ch1_left) / 3;
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// const right = (chA_right + chB_right + ch1_right) / 3
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const left = ch1_left;
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const right = ch1_right;
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// const left = (chA_left + chB_left + psg_left) / 3;
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// const right = (chA_right + chB_right + psg_right) / 3
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const left = psg_left;
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const right = psg_right;
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if (self.sampling_cycle != self.bias.sampling_cycle.read()) {
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log.warn("Sampling Cycle changed from {} to {}", .{ self.sampling_cycle, self.bias.sampling_cycle.read() });
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@ -176,7 +207,7 @@ pub const Apu = struct {
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1, 3, 5 => {},
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}
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self.sched.push(.FrameSequencer, self.sched.now() + ((1 << 24) / 1 << 15) - late);
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self.sched.push(.FrameSequencer, self.sched.now() + ((1 << 24) / 512) - late);
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}
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fn tickLengths(self: *Self) void {
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@ -205,6 +236,18 @@ pub const Apu = struct {
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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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fn highPassFilter(self: *Self, sample: f32, ch_enabled: bool) f32 {
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const charge_factor = 0.999958;
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var output: f32 = 0;
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if (ch_enabled) {
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output = sample - self.capacitor;
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self.capacitor = sample - output * std.math.pow(f32, charge_factor, @intToFloat(f32, (1 << 22) / self.sampleRate()));
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}
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return output;
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}
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};
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const ToneSweep = struct {
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@ -221,15 +264,12 @@ const ToneSweep = struct {
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/// Length Functionality
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len_dev: Length,
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/// Sweep Functionality
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sweep_dev: Sweep,
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/// Envelope Functionality
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env_dev: Envelope,
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/// Frequency Timer Functionality
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square: SquareWave,
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enabled: bool,
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sample: u8,
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@ -257,11 +297,11 @@ const ToneSweep = struct {
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this.timer = if (period == 0) 8 else period;
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if (this.enabled and period != 0) {
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const new_freq: u11 = this.calcFrequency(ch1);
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const new_freq = this.calcFrequency(ch1);
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if (new_freq <= 0x7FF and ch1.sweep.shift.read() != 0) {
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ch1.freq.frequency.write(new_freq);
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this.shadow = new_freq;
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ch1.freq.frequency.write(@truncate(u11, new_freq));
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this.shadow = @truncate(u11, new_freq);
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_ = this.calcFrequency(ch1);
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}
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@ -269,10 +309,12 @@ const ToneSweep = struct {
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}
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}
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fn calcFrequency(this: *This, ch1: *Self) u11 {
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const shadow_shifted = this.shadow >> ch1.sweep.shift.read();
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fn calcFrequency(this: *This, ch1: *Self) u12 {
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const shadow = @as(u12, this.shadow);
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const shadow_shifted = shadow >> ch1.sweep.shift.read();
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const decrease = ch1.sweep.direction.read();
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const freq = if (decrease) this.shadow - shadow_shifted else this.shadow + shadow_shifted;
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const freq = if (decrease) shadow - shadow_shifted else shadow + shadow_shifted;
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if (freq > 0x7FF) ch1.enabled = false;
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@ -296,6 +338,16 @@ const ToneSweep = struct {
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};
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}
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fn reset(self: *Self) void {
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self.sweep.raw = 0;
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self.duty.raw = 0;
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self.envelope.raw = 0;
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self.freq.raw = 0;
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self.sample = 0;
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self.enabled = false;
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}
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fn tickSweep(self: *Self) void {
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self.sweep_dev.tick(self);
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}
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@ -313,17 +365,23 @@ const ToneSweep = struct {
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self.sample = 0;
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if (!self.isDacEnabled()) return;
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self.sample = if (self.enabled) self.square.getSample(self.duty) * self.env_dev.vol else 0;
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self.sample = if (self.enabled) self.square.sample(self.duty) * self.env_dev.vol else 0;
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}
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fn amplitude(self: *const Self) f32 {
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return (@intToFloat(f32, self.sample) / 7.5) - 1.0;
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}
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/// NR11, NR12
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pub fn setSoundCntH(self: *Self, value: u16) void {
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self.setDuty(@truncate(u8, value));
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self.setEnvelope(@truncate(u8, value >> 8));
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}
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/// NR11
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pub fn setDuty(self: *Self, value: u8) void {
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self.duty.raw = value;
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self.len_dev.timer = 64 - self.duty.length.read();
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self.len_dev.timer = @as(u7, self.duty.length.read() ^ 0x3F);
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}
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/// NR12
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@ -332,25 +390,35 @@ const ToneSweep = struct {
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if (!self.isDacEnabled()) self.enabled = false;
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}
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/// NR13, NR14
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pub fn setFreq(self: *Self, fs: *const FrameSequencer, value: u16) void {
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self.setFreqLow(@truncate(u8, value));
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self.setFreqHigh(fs, @truncate(u8, value >> 8));
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}
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/// NR13
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pub fn setFreqLow(self: *Self, byte: u8) void {
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self.freq.raw = (self.freq.raw & 0xFF00) | byte;
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}
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/// NR14
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pub fn setFreqHigh(self: *Self, byte: u8) void {
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pub fn setFreqHigh(self: *Self, fs: *const FrameSequencer, byte: u8) void {
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var new: io.Frequency = .{ .raw = (@as(u16, byte) << 8) | (self.freq.raw & 0xFF) };
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if (new.trigger.read()) {
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self.enabled = true; // FIXME: is this necessary?
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if (self.len_dev.timer == 0) {
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self.len_dev.timer = 64;
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// FIXME: This conflicts with my GB emulator
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new.length_enable.write(false);
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// We unset this on the old frequency because of the obscure
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// behaviour outside of this if statement's scope
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self.freq.length_enable.write(false);
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}
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// TODO: Reload Frequency Timer (last two bits unmodified)
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// TODO: Reload Frequency Timer
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self.square.reloadTimer(self.freq.frequency.read());
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// Reload Envelope period and timer
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self.env_dev.timer = self.envelope.period.read();
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self.env_dev.vol = self.envelope.init_vol.read();
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@ -367,6 +435,7 @@ const ToneSweep = struct {
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self.enabled = self.isDacEnabled();
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}
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self.square.updateLength(fs, self, new);
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self.freq = new;
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}
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@ -559,12 +628,16 @@ const FrameSequencer = struct {
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pub fn tick(self: *Self) void {
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self.step +%= 1;
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}
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fn lengthIsNext(self: *const Self) bool {
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return (self.step +% 1) & 1 == 0; // Steps, 0, 2, 4, and 6 clock length
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}
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};
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const Length = struct {
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const Self = @This();
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timer: u16,
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timer: u7,
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pub fn init() Self {
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return .{ .timer = 0 };
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@ -613,9 +686,9 @@ const Envelope = struct {
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self.timer = cnt.period.read();
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if (cnt.direction.read()) {
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if (self.vol > 0x0) self.vol -= 1;
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} else {
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if (self.vol < 0xF) self.vol += 1;
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} else {
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if (self.vol > 0x0) self.vol -= 1;
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}
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}
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}
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@ -624,43 +697,57 @@ const Envelope = struct {
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const SquareWave = struct {
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const Self = @This();
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const ticks: u64 = (1 << 24) / (1 << 18);
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const ticks: u64 = (1 << 24) / (1 << 22);
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pos: u3,
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sched: *Scheduler,
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timer: u12,
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pub fn init(sched: *Scheduler) Self {
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return .{
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.timer = 0,
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.pos = 0,
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.sched = sched,
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};
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}
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fn handleTimerOverflow(self: *Self, cnt: io.Frequency, late: u64) void {
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const when = (2048 - @as(u64, cnt.frequency.read())) * 4;
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/// Obscure NRx4 Behaviour
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fn updateLength(_: *Self, fs: *const FrameSequencer, ch1: *ToneSweep, new_cnt: io.Frequency) void {
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if (!fs.lengthIsNext() and !ch1.freq.length_enable.read() and new_cnt.length_enable.read() and ch1.len_dev.timer != 0) {
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ch1.len_dev.timer -= 1;
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if (ch1.len_dev.timer == 0 and !new_cnt.trigger.read()) ch1.enabled = false;
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}
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}
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fn handleTimerOverflow(self: *Self, cnt: io.Frequency, late: u64) void {
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const timer = (2048 - @as(u64, cnt.frequency.read())) * 4;
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self.timer = @truncate(u12, timer);
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self.pos = (self.pos +% 1) & 7;
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self.sched.push(.{ .ApuChannel = 0 }, when * ticks - late);
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self.sched.push(.{ .ApuChannel = 0 }, self.sched.now() + timer * ticks - late);
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}
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fn reloadTimer(self: *Self, value: u11) void {
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self.sched.removeScheduledEvent(.{ .ApuChannel = 0 });
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// TODO: Implement Obscure Behaviour
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const when = (2048 - @as(u64, value)) * 4;
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const tmp: u64 = (2048 - @as(u64, value)) * 4; // What Freq Timer should be assuming no weird behaviour
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const timer = (tmp & ~@as(u64, 0x3)) | self.timer & 0x3; // Keep the last two bits from the old timer
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self.timer = @truncate(u12, timer);
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self.sched.push(.{ .ApuChannel = 0 }, when * ticks);
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self.sched.push(.{ .ApuChannel = 0 }, self.sched.now() + timer * ticks);
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}
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fn getSample(self: *const Self, cnt: io.Duty) u1 {
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const pattern = cnt.pattern.read(); // 2^18
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fn sample(self: *const Self, cnt: io.Duty) u1 {
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const pattern = cnt.pattern.read();
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const i = self.pos ^ 7; // index of 0 should get highest bit
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const result = switch (pattern) {
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0b00 => @as(u8, 0b00000001) >> i, // 1/8th
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0b01 => @as(u8, 0b10000001) >> i, // 1/4th
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0b10 => @as(u8, 0b10000111) >> i, // 1/2nd
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0b11 => @as(u8, 0b01111110) >> i, // 3/4th
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0b00 => @as(u8, 0b00000001) >> i, // 12.5%
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0b01 => @as(u8, 0b00000011) >> i, // 25%
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0b10 => @as(u8, 0b00001111) >> i, // 50%
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0b11 => @as(u8, 0b11111100) >> i, // 75%
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};
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return @truncate(u1, result);
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@ -118,7 +118,7 @@ pub fn read(bus: *const Bus, comptime T: type, address: u32) T {
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0x0400_0073 => bus.apu.ch3.vol.raw,
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0x0400_0079 => bus.apu.ch4.envelope.raw,
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0x0400_007C => bus.apu.ch4.poly.raw,
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0x0400_0081 => @truncate(T, bus.apu.ch_vol_cnt.raw >> 8),
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0x0400_0081 => @truncate(T, bus.apu.psg_cnt.raw >> 8),
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0x0400_0089 => @truncate(T, bus.apu.bias.raw >> 8),
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// Serial Communication 1
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@ -151,7 +151,7 @@ pub fn write(bus: *Bus, comptime T: type, address: u32, value: T) void {
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// Sound
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0x0400_0080 => {
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bus.apu.ch_vol_cnt.raw = @truncate(u16, value);
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bus.apu.psg_cnt.raw = @truncate(u16, value);
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bus.apu.dma_cnt.raw = @truncate(u16, value >> 16);
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},
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0x0400_00A0 => bus.apu.chA.push(value),
|
||||
|
|
@ -232,7 +232,10 @@ pub fn write(bus: *Bus, comptime T: type, address: u32, value: T) void {
|
|||
0x0400_004E, 0x0400_0056 => {}, // Not used
|
||||
|
||||
// Sound
|
||||
0x0400_0080 => bus.apu.ch_vol_cnt.raw = value,
|
||||
0x0400_0060 => bus.apu.ch1.sweep.raw = @truncate(u8, value),
|
||||
0x0400_0062 => bus.apu.ch1.setSoundCntH(value),
|
||||
0x0400_0064 => bus.apu.ch1.setFreq(&bus.apu.fs, value),
|
||||
0x0400_0080 => bus.apu.psg_cnt.raw = value,
|
||||
0x0400_0082 => bus.apu.setDmaCnt(value),
|
||||
0x0400_0084 => bus.apu.setSoundCntX(value >> 7 & 1 == 1),
|
||||
0x0400_0088 => bus.apu.bias.raw = value,
|
||||
|
|
@ -314,7 +317,7 @@ pub fn write(bus: *Bus, comptime T: type, address: u32, value: T) void {
|
|||
0x0400_0062 => bus.apu.ch1.duty.raw = value,
|
||||
0x0400_0063 => bus.apu.ch1.envelope.raw = value,
|
||||
0x0400_0064 => bus.apu.ch1.setFreqLow(value),
|
||||
0x0400_0065 => bus.apu.ch1.setFreqHigh(value),
|
||||
0x0400_0065 => bus.apu.ch1.setFreqHigh(&bus.apu.fs, value),
|
||||
0x0400_0068 => bus.apu.ch2.duty.raw = value,
|
||||
0x0400_0069 => bus.apu.ch2.envelope.raw = value,
|
||||
0x0400_006C => bus.apu.ch2.setFreqLow(value),
|
||||
|
|
@ -578,8 +581,8 @@ pub const NoiseControl = extern union {
|
|||
|
||||
/// Read / Write
|
||||
pub const ChannelVolumeControl = extern union {
|
||||
left_vol: Bitfield(u16, 0, 3),
|
||||
right_vol: Bitfield(u16, 4, 3),
|
||||
right_vol: Bitfield(u16, 0, 3),
|
||||
left_vol: Bitfield(u16, 4, 3),
|
||||
|
||||
ch1_right: Bit(u16, 8),
|
||||
ch2_right: Bit(u16, 9),
|
||||
|
|
|
|||
Loading…
Reference in New Issue