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chore: clean up DMA code

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-05-05 22:36:11 -03:00
parent 9d590b099a
commit 660c8a2d62
2 changed files with 25 additions and 21 deletions
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4
src/apu.zig
View File

@ -263,12 +263,12 @@ pub const Apu = struct {
if (@boolToInt(self.dma_cnt.chA_timer.read()) == tim_id) {
self.chA.updateSample();
if (self.chA.len() <= 15) cpu.bus.dma[1].enableSoundDma(0x0400_00A0);
if (self.chA.len() <= 15) cpu.bus.dma[1].requestSoundDma(0x0400_00A0);
}
if (@boolToInt(self.dma_cnt.chB_timer.read()) == tim_id) {
self.chB.updateSample();
if (self.chB.len() <= 15) cpu.bus.dma[2].enableSoundDma(0x0400_00A4);
if (self.chB.len() <= 15) cpu.bus.dma[2].requestSoundDma(0x0400_00A4);
}
}

34
src/bus/dma.zig
View File

@ -102,11 +102,11 @@ fn DmaController(comptime id: u2) type {
pub fn step(self: *Self, cpu: *Arm7tdmi) bool {
if (!self.active) return false;
const sad_adj = std.meta.intToEnum(Adjustment, self.cnt.sad_adj.read()) catch unreachable;
const dad_adj = std.meta.intToEnum(Adjustment, self.cnt.dad_adj.read()) catch unreachable;
const is_fifo = (self.id == 1 or self.id == 2) and self.cnt.start_timing.read() == 0b11;
const sad_adj = Self.adjustment(self.cnt.sad_adj.read());
const dad_adj = if (is_fifo) .Fixed else Self.adjustment(self.cnt.dad_adj.read());
const transfer_type = self.cnt.transfer_type.read() or is_fifo;
const transfer_type = is_fifo or self.cnt.transfer_type.read();
const offset: u32 = if (transfer_type) @sizeOf(u32) else @sizeOf(u16);
if (transfer_type) {
@ -118,19 +118,16 @@ fn DmaController(comptime id: u2) type {
switch (sad_adj) {
.Increment => self._sad +%= offset,
.Decrement => self._sad -%= offset,
// TODO: Is just ignoring this ok?
.IncrementReload => log.err("{} is a prohibited adjustment on SAD", .{sad_adj}),
.Fixed => {},
// TODO: Figure out correct behaviour on Illegal Source Addr Control Type
.IncrementReload => std.debug.panic("panic(DmaTransfer): {} is an illegal src addr adjustment type", .{sad_adj}),
}
if (!is_fifo) {
switch (dad_adj) {
.Increment, .IncrementReload => self._dad +%= offset,
.Decrement => self._dad -%= offset,
.Fixed => {},
}
}
self._word_count -= 1;
@ -176,21 +173,28 @@ fn DmaController(comptime id: u2) type {
if (self.cnt.repeat.read() and self.active) {
self._word_count = if (self.word_count == 0) std.math.maxInt(@TypeOf(self._word_count)) else self.word_count;
const dad_adj = std.meta.intToEnum(Adjustment, self.cnt.dad_adj.read()) catch unreachable;
if (dad_adj == .IncrementReload) self._dad = self.dad;
if (Self.adjustment(self.cnt.dad_adj.read()) == .IncrementReload) self._dad = self.dad;
}
}
pub fn enableSoundDma(self: *Self, fifo_addr: u32) void {
pub fn requestSoundDma(self: *Self, fifo_addr: u32) void {
comptime std.debug.assert(id == 1 or id == 2);
if (self.cnt.enabled.read() and self.cnt.start_timing.read() == 0b11 and self.dad == fifo_addr) {
self.active = true;
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.repeat.set();
self.cnt.transfer_type.set();
self.active = true;
}
}
fn adjustment(idx: u2) Adjustment {
return std.meta.intToEnum(Adjustment, idx) catch unreachable;
}
};
}