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feat: implement NR10 obscure behaviour

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-06-18 18:16:29 -03:00
parent 601b0b2aae
commit 47adc0c5ae
1 changed files with 25 additions and 3 deletions
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28
src/apu.zig
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@ -81,7 +81,7 @@ pub fn write(comptime T: type, apu: *Apu, addr: u32, value: T) void {
else => writeUndefined(log, "Tried to write 0x{X:0>8}{} to 0x{X:0>8}", .{ value, T, addr }),
},
u16 => switch (byte) {
0x60 => apu.ch1.sweep.raw = @truncate(u8, value), // SOUND1CNT_L
0x60 => apu.ch1.setSoundCntL(@truncate(u8, value)), // SOUND1CNT_L
0x62 => apu.ch1.setSoundCntH(value),
0x64 => apu.ch1.setSoundCntX(&apu.fs, value),
@ -104,7 +104,7 @@ pub fn write(comptime T: type, apu: *Apu, addr: u32, value: T) void {
else => writeUndefined(log, "Tried to write 0x{X:0>4}{} to 0x{X:0>8}", .{ value, T, addr }),
},
u8 => switch (byte) {
0x60 => apu.ch1.sweep.raw = value, // NR10
0x60 => apu.ch1.setSoundCntL(value),
0x62 => apu.ch1.setNr11(value),
0x63 => apu.ch1.setNr12(value),
0x64 => apu.ch1.setNr13(value),
@ -443,11 +443,14 @@ const ToneSweep = struct {
enabled: bool,
shadow: u11,
calc_performed: bool,
pub fn init() This {
return .{
.timer = 0,
.enabled = false,
.shadow = 0,
.calc_performed = false,
};
}
@ -457,6 +460,7 @@ const ToneSweep = struct {
if (this.timer == 0) {
const period = ch1.sweep.period.read();
this.timer = if (period == 0) 8 else period;
if (!this.calc_performed) this.calc_performed = true;
if (this.enabled and period != 0) {
const new_freq = this.calcFrequency(ch1);
@ -502,6 +506,8 @@ const ToneSweep = struct {
fn reset(self: *Self) void {
self.sweep.raw = 0;
self.sweep_dev.calc_performed = false;
self.duty.raw = 0;
self.envelope.raw = 0;
self.freq.raw = 0;
@ -536,7 +542,7 @@ const ToneSweep = struct {
/// NR10, NR11, NR12
fn setSoundCnt(self: *Self, value: u32) void {
self.sweep.raw = @truncate(u8, value);
self.setSoundCntL(@truncate(u8, value));
self.setSoundCntH(@truncate(u16, value >> 16));
}
@ -545,6 +551,21 @@ const ToneSweep = struct {
return self.sweep.raw & 0x7F;
}
/// NR10
fn setSoundCntL(self: *Self, value: u8) void {
const new = io.Sweep{ .raw = value };
if (self.sweep.direction.read() and !new.direction.read()) {
// Sweep Negate bit has been cleared
// If At least 1 Sweep Calculation has been made since
// the last trigger, the channel is immediately disabled
if (self.sweep_dev.calc_performed) self.enabled = false;
}
self.sweep.raw = value;
}
/// NR11, NR12
pub fn getSoundCntH(self: *const Self) u16 {
return @as(u16, self.envelope.raw) << 8 | (self.duty.raw & 0xC0);
@ -608,6 +629,7 @@ const ToneSweep = struct {
const sw_period = self.sweep.period.read();
const sw_shift = self.sweep.shift.read();
self.sweep_dev.calc_performed = false;
self.sweep_dev.shadow = self.freq.frequency.read();
self.sweep_dev.timer = if (sw_period == 0) 8 else sw_period;
self.sweep_dev.enabled = sw_period != 0 or sw_shift != 0;