diff --git a/src/apu.zig b/src/apu.zig index 3b0c025..8896cac 100644 --- a/src/apu.zig +++ b/src/apu.zig @@ -969,7 +969,7 @@ const WaveDevice = struct { const timer = (2048 - @as(u64, value)) * 4; self.timer = @truncate(u11, timer); - self.sched.push(.{ .ApuChannel = 2 }, timer * tickInterval); + self.sched.push(.{ .ApuChannel = 2 }, (timer + 1) * tickInterval); } fn handleTimerOverflow(self: *Self, cnt_freq: io.Frequency, cnt_sel: io.WaveSelect, late: u64) void { @@ -983,7 +983,7 @@ const WaveDevice = struct { self.offset = (self.offset + 1) % 0x20; // 0x10 bytes, which contain 2 samples each } - self.sched.push(.{ .ApuChannel = 2 }, timer * tickInterval -| late); + self.sched.push(.{ .ApuChannel = 2 }, (timer + 1) * tickInterval -| late); } fn sample(self: *const Self, cnt: io.WaveSelect) u4 { @@ -1094,7 +1094,7 @@ const SquareWave = struct { self.timer = @truncate(u12, timer); self.pos +%= 1; - self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, timer * tickInterval -| late); + self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, (timer + 1) * tickInterval -| late); } fn reloadTimer(self: *Self, comptime kind: ChannelKind, value: u11) void { @@ -1104,7 +1104,7 @@ const SquareWave = struct { const timer = (tmp & ~@as(u64, 0x3)) | self.timer & 0x3; // Keep the last two bits from the old timer self.timer = @truncate(u12, timer); - self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, timer * tickInterval); + self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, (timer + 1) * tickInterval); } fn sample(self: *const Self, cnt: io.Duty) u1 { @@ -1165,20 +1165,23 @@ const Lfsr = struct { const div = Self.divisor(poly.div_ratio.read()); const timer = @as(u64, div << poly.shift.read()); - self.sched.push(.{ .ApuChannel = 3 }, timer * tickInterval); + self.sched.push(.{ .ApuChannel = 3 }, (timer + 1) * tickInterval); } fn handleTimerOverflow(self: *Self, poly: io.PolyCounter, late: u64) void { const div = Self.divisor(poly.div_ratio.read()); const timer = @as(u64, div << poly.shift.read()); + // Obscure: Clock Shift of 14 or 15 results in LSFR receiving no clocks + if (poly.shift.read() > 14) return; + const tmp = (self.shift & 1) ^ ((self.shift & 2) >> 1); self.shift = (self.shift >> 1) | (tmp << 14); if (poly.width.read()) self.shift = (self.shift & ~@as(u15, 0x40)) | tmp << 6; - self.sched.push(.{ .ApuChannel = 3 }, timer * tickInterval -| late); + self.sched.push(.{ .ApuChannel = 3 }, (timer + 1) * tickInterval -| late); } fn divisor(code: u3) u16 {