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fix: properly fire DMA IRQs 

This resolves Sound DMA Timing issues present in DOOM
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-06-18 21:13:12 -03:00
parent adfb23fab4
commit 4cd722e447
1 changed files with 43 additions and 25 deletions
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68
src/bus/dma.zig
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@ -205,22 +205,20 @@ fn DmaController(comptime id: u2) type {
self._word_count -= 1;
if (self._word_count == 0) {
if (!self.cnt.repeat.read()) {
// If we're not repeating, Fire the IRQs and disable the DMA
if (self.cnt.irq.read()) {
switch (id) {
0 => cpu.bus.io.irq.dma0.set(),
1 => cpu.bus.io.irq.dma0.set(),
2 => cpu.bus.io.irq.dma0.set(),
3 => cpu.bus.io.irq.dma0.set(),
}
cpu.handleInterrupt();
if (self.cnt.irq.read()) {
switch (id) {
0 => cpu.bus.io.irq.dma0.set(),
1 => cpu.bus.io.irq.dma1.set(),
2 => cpu.bus.io.irq.dma2.set(),
3 => cpu.bus.io.irq.dma3.set(),
}
self.cnt.enabled.unset();
cpu.handleInterrupt();
}
// If we're not repeating, Fire the IRQs and disable the DMA
if (!self.cnt.repeat.read()) self.cnt.enabled.unset();
// We want to disable our internal enabled flag regardless of repeat
// because we only want to step A DMA that repeats during it's specific
// timing window
@ -229,15 +227,20 @@ fn DmaController(comptime id: u2) type {
}
pub fn pollBlankingDma(self: *Self, comptime kind: DmaKind) void {
if (self.in_progress) return;
if (self.in_progress) return; // If there's an ongoing DMA Transfer, exit early
// No ongoing DMA Transfer, We want to check if we should repeat an existing one
// Determined by the repeat bit and whether the DMA is in the right start_timing
switch (kind) {
.HBlank => self.in_progress = self.cnt.enabled.read() and self.cnt.start_timing.read() == 0b10,
.VBlank => self.in_progress = self.cnt.enabled.read() and self.cnt.start_timing.read() == 0b01,
.HBlank => self.in_progress = self.cnt.enabled.read() and self.cnt.start_timing.read() == 0b10,
.Immediate, .Special => {},
}
if (self.cnt.repeat.read() and self.in_progress) {
// If we determined that the repeat bit is set (and now the Hblank / Vblank DMA is now in progress)
// Reload internal word count latch
// Reload internal DAD latch if we are in IncrementRelaod
if (self.in_progress) {
self._word_count = if (self.word_count == 0) std.math.maxInt(@TypeOf(self._word_count)) else self.word_count;
if (Self.adjustment(self.cnt.dad_adj.read()) == .IncrementReload) self._dad = self.dad;
}
@ -245,17 +248,32 @@ fn DmaController(comptime id: u2) type {
pub fn requestSoundDma(self: *Self, fifo_addr: u32) void {
comptime std.debug.assert(id == 1 or id == 2);
const is_enabled = self.cnt.enabled.read();
const is_special = self.cnt.start_timing.read() == 0b11;
const is_repeating = self.cnt.repeat.read();
const is_fifo = self.dad == fifo_addr;
if (is_enabled and is_special and is_repeating and is_fifo) {
self._word_count = 4;
self.cnt.transfer_type.set();
self.in_progress = true;
if (self.in_progress) {
log.err("DMA{} Sound Request but DMA{} is already running?", .{ id, id });
return;
}
if (self.cnt.start_timing.read() != 0b11) {
log.err("APU requested Sound DMA from DMA{}, but the DMA was not configured for Sound", .{id});
return;
}
// log.err("DMA{}: SAD = 0x{X:0>8}, DAD = 0x{X:0>8}, WC = 0x{X:}", .{ id, self.sad, self.dad, self.word_count });
// log.err("\tSAD Adjustment: {}", .{Self.adjustment(self.cnt.sad_adj.read())});
// log.err("\tDAD Adjustment: {}", .{Self.adjustment(self.cnt.dad_adj.read())});
// log.err("\tRepeat: {}", .{@boolToInt(self.cnt.repeat.read())});
// log.err("\tTransfer Type: {}-bit", .{if (self.cnt.transfer_type.read()) @as(u32, 32) else 16});
// log.err("\tStart Timing: {}", .{self.cnt.start_timing.read()});
// We Assume the Repeat Bit is Set
// We Assume that DAD is set to 0x0400_00A0 or 0x0400_00A4 (fifo_addr)
// We Assume DMACNT_L is set to 4
self.cnt.repeat.set();
self._dad = fifo_addr;
self._word_count = 4;
self.in_progress = true;
}
fn adjustment(idx: u2) Adjustment {