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feat(dma): Implement DMA Latch #5

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paoda merged 1 commits from dma-latch into main 2022-10-22 23:53:21 +00:00
Conversation 0 Commits 1 Files Changed 1 +20 -5
1 changed files with 20 additions and 5 deletions
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25
src/core/bus/dma.zig
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@ -11,6 +11,8 @@ const log = std.log.scoped(.DmaTransfer);
const setHi = util.setHi;
const setLo = util.setLo;
const rotr = @import("../../util.zig").rotr;
pub fn create() DmaTuple {
return .{ DmaController(0).init(), DmaController(1).init(), DmaController(2).init(), DmaController(3).init() };
}
@ -99,6 +101,7 @@ fn DmaController(comptime id: u2) type {
const sad_mask: u32 = if (id == 0) 0x07FF_FFFF else 0x0FFF_FFFF;
const dad_mask: u32 = if (id != 3) 0x07FF_FFFF else 0x0FFF_FFFF;
const WordCount = if (id == 3) u16 else u14;
/// Write-only. The first address in a DMA transfer. (DMASAD)
/// Note: use writeSrc instead of manipulating src_addr directly
@ -107,17 +110,19 @@ fn DmaController(comptime id: u2) type {
/// Note: Use writeDst instead of manipulatig dst_addr directly
dad: u32,
/// Write-only. The Word Count for the DMA Transfer (DMACNT_L)
word_count: if (id == 3) u16 else u14,
word_count: WordCount,
/// Read / Write. DMACNT_H
/// Note: Use writeControl instead of manipulating cnt directly.
cnt: DmaControl,
/// Internal. The last successfully read value
data_latch: u32,
/// Internal. Currrent Source Address
sad_latch: u32,
/// Internal. Current Destination Address
dad_latch: u32,
/// Internal. Word Count
_word_count: if (id == 3) u16 else u14,
_word_count: WordCount,
/// Some DMA Transfers are enabled during Hblank / VBlank and / or
/// have delays. Thefore bit 15 of DMACNT isn't actually something
@ -134,6 +139,8 @@ fn DmaController(comptime id: u2) type {
// Internals
.sad_latch = 0,
.dad_latch = 0,
.data_latch = 0,
._word_count = 0,
.in_progress = false,
};
@ -158,7 +165,7 @@ fn DmaController(comptime id: u2) type {
// Reload Internals on Rising Edge.
self.sad_latch = self.sad;
self.dad_latch = self.dad;
self._word_count = if (self.word_count == 0) std.math.maxInt(@TypeOf(self._word_count)) else self.word_count;
self._word_count = if (self.word_count == 0) std.math.maxInt(WordCount) else self.word_count;
// Only a Start Timing of 00 has a DMA Transfer immediately begin
self.in_progress = new.start_timing.read() == 0b00;
@ -181,11 +188,19 @@ fn DmaController(comptime id: u2) type {
const offset: u32 = if (transfer_type) @sizeOf(u32) else @sizeOf(u16);
const mask = if (transfer_type) ~@as(u32, 3) else ~@as(u32, 1);
const sad_addr = self.sad_latch & mask;
const dad_addr = self.dad_latch & mask;
if (transfer_type) {
cpu.bus.write(u32, self.dad_latch & mask, cpu.bus.read(u32, self.sad_latch & mask));
if (sad_addr >= 0x0200_0000) self.data_latch = cpu.bus.read(u32, sad_addr);
cpu.bus.write(u32, dad_addr, self.data_latch);
} else {
cpu.bus.write(u16, self.dad_latch & mask, cpu.bus.read(u16, self.sad_latch & mask));
if (sad_addr >= 0x0200_0000) {
const value: u32 = cpu.bus.read(u16, sad_addr);
self.data_latch = value << 16 | value;
}
cpu.bus.write(u16, dad_addr, @truncate(u16, rotr(u32, self.data_latch, 8 * (dad_addr & 3))));
}
switch (sad_adj) {