diff --git a/src/core/bus/dma.zig b/src/core/bus/dma.zig index 0d25bd0..a0404df 100644 --- a/src/core/bus/dma.zig +++ b/src/core/bus/dma.zig @@ -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) {