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Revert "fix: resolve off-by-one errors when scheduling freq timer expirations" 

This reverts commit c9b0030b4b.
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-05-21 13:46:46 -03:00
parent c9b0030b4b
commit 5164aa961d
1 changed files with 6 additions and 9 deletions
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15
src/apu.zig
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@ -969,7 +969,7 @@ const WaveDevice = struct {
const timer = (2048 - @as(u64, value)) * 4; const timer = (2048 - @as(u64, value)) * 4;
self.timer = @truncate(u11, timer); self.timer = @truncate(u11, timer);
self.sched.push(.{ .ApuChannel = 2 }, (timer + 1) * tickInterval); self.sched.push(.{ .ApuChannel = 2 }, timer * tickInterval);
} }
fn handleTimerOverflow(self: *Self, cnt_freq: io.Frequency, cnt_sel: io.WaveSelect, late: u64) void { 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.offset = (self.offset + 1) % 0x20; // 0x10 bytes, which contain 2 samples each
} }
self.sched.push(.{ .ApuChannel = 2 }, (timer + 1) * tickInterval -| late); self.sched.push(.{ .ApuChannel = 2 }, timer * tickInterval -| late);
} }
fn sample(self: *const Self, cnt: io.WaveSelect) u4 { fn sample(self: *const Self, cnt: io.WaveSelect) u4 {
@ -1094,7 +1094,7 @@ const SquareWave = struct {
self.timer = @truncate(u12, timer); self.timer = @truncate(u12, timer);
self.pos +%= 1; self.pos +%= 1;
self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, (timer + 1) * tickInterval -| late); self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, timer * tickInterval -| late);
} }
fn reloadTimer(self: *Self, comptime kind: ChannelKind, value: u11) void { 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 const timer = (tmp & ~@as(u64, 0x3)) | self.timer & 0x3; // Keep the last two bits from the old timer
self.timer = @truncate(u12, timer); self.timer = @truncate(u12, timer);
self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, (timer + 1) * tickInterval); self.sched.push(.{ .ApuChannel = if (kind == .Ch1) 0 else 1 }, timer * tickInterval);
} }
fn sample(self: *const Self, cnt: io.Duty) u1 { fn sample(self: *const Self, cnt: io.Duty) u1 {
@ -1165,23 +1165,20 @@ const Lfsr = struct {
const div = Self.divisor(poly.div_ratio.read()); const div = Self.divisor(poly.div_ratio.read());
const timer = @as(u64, div << poly.shift.read()); const timer = @as(u64, div << poly.shift.read());
self.sched.push(.{ .ApuChannel = 3 }, (timer + 1) * tickInterval); self.sched.push(.{ .ApuChannel = 3 }, timer * tickInterval);
} }
fn handleTimerOverflow(self: *Self, poly: io.PolyCounter, late: u64) void { fn handleTimerOverflow(self: *Self, poly: io.PolyCounter, late: u64) void {
const div = Self.divisor(poly.div_ratio.read()); const div = Self.divisor(poly.div_ratio.read());
const timer = @as(u64, div << poly.shift.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); const tmp = (self.shift & 1) ^ ((self.shift & 2) >> 1);
self.shift = (self.shift >> 1) | (tmp << 14); self.shift = (self.shift >> 1) | (tmp << 14);
if (poly.width.read()) if (poly.width.read())
self.shift = (self.shift & ~@as(u15, 0x40)) | tmp << 6; self.shift = (self.shift & ~@as(u15, 0x40)) | tmp << 6;
self.sched.push(.{ .ApuChannel = 3 }, (timer + 1) * tickInterval -| late); self.sched.push(.{ .ApuChannel = 3 }, timer * tickInterval -| late);
} }
fn divisor(code: u3) u16 { fn divisor(code: u3) u16 {