Fix DMA mode 1 length

twvd · Oct 29, 2023 · 72fb230 · 72fb230
1 parent 5c9af5e
commit 72fb230
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Showing 2 changed files with 22 additions and 35 deletions.
diff --git a/src/snes/bus/mainbus.rs b/src/snes/bus/mainbus.rs
@@ -107,11 +107,11 @@ impl DMAChannel {
         }
     }
 
-    pub fn len(&self) -> usize {
+    pub fn len(&self) -> Address {
         if self.das == 0 {
             0x10000
         } else {
-            self.das as usize
+            Address::from(self.das + (self.das % 4))
         }
     }
 
@@ -152,46 +152,33 @@ where
                 dbg_hex!(&self.dma[ch]);
             }
 
-            match self.dma[ch].mode() {
-                0 => {
-                    for i in 0..(self.dma[ch].len() as Address) {
-                        let b_addr = self.dma[ch].b_addr();
-                        match self.dma[ch].direction() {
-                            DMADirection::CPUToIO => {
-                                let a_addr = match self.dma[ch].step() {
-                                    DMAStep::Increment => self.dma[ch].a_addr() + i,
-                                    DMAStep::Fixed => self.dma[ch].a_addr(),
-                                    _ => todo!(),
-                                };
-
-                                let v = self.read(a_addr);
-                                self.write(b_addr, v);
-                            }
-                            _ => todo!(),
+            for i in 0..self.dma[ch].len() {
+                let b_addr = self.dma[ch].b_addr();
+                let a_addr = match self.dma[ch].step() {
+                    DMAStep::Increment => self.dma[ch].a_addr() + i,
+                    DMAStep::Fixed => self.dma[ch].a_addr(),
+                    _ => todo!(),
+                };
+                match self.dma[ch].mode() {
+                    0 => match self.dma[ch].direction() {
+                        DMADirection::CPUToIO => {
+                            let v = self.read(a_addr);
+                            self.write(b_addr, v);
                         }
-                    }
-                }
-                1 => {
-                    for i in 0..(self.dma[ch].len() as Address) {
-                        let b_addr = self.dma[ch].b_addr();
+                        _ => todo!(),
+                    },
+                    1 => {
+                        let b_addr = b_addr + (i & 1);
                         match self.dma[ch].direction() {
                             DMADirection::CPUToIO => {
-                                let a_addr = match self.dma[ch].step() {
-                                    DMAStep::Increment => self.dma[ch].a_addr() + (i * 2),
-                                    DMAStep::Fixed => self.dma[ch].a_addr(),
-                                    _ => todo!(),
-                                };
-
                                 let v = self.read(a_addr);
                                 self.write(b_addr, v);
-                                let v2 = self.read(a_addr + 1);
-                                self.write(b_addr + 1, v2);
                             }
                             _ => todo!(),
                         }
                     }
+                    _ => todo!(),
                 }
-                _ => todo!(),
             }
         }
     }

diff --git a/src/snes/ppu/mod.rs b/src/snes/ppu/mod.rs
@@ -20,12 +20,12 @@ type VramWord = u16;
 const VRAM_WORDS: usize = 32 * 1024;
 const VRAM_WORDSIZE: usize = 2;
 // 32K-words addressable (64KB)
-const VRAM_ADDRMASK: usize = 0x7FFF;
+const VRAM_ADDRMASK: usize = VRAM_WORDS - 1;
 
 type CgramWord = u16;
 const CGRAM_WORDS: usize = 256;
 const CGRAM_WORDSIZE: usize = 2;
-const CGRAM_ADDRMASK: usize = 0xFF;
+const CGRAM_ADDRMASK: usize = CGRAM_WORDS - 1;
 
 // VMAIN bits
 const VMAIN_HIGH: u8 = 1 << 7;
@@ -202,7 +202,7 @@ where
             0 => {
                 if !self.is_layer_16x16(bg) {
                     let tm_x = x / 8;
-                    let tm_y = y.rem_euclid(32 * 8) / 8;
+                    let tm_y = y % (32 * 8) / 8;
                     self.get_tilemap_entry(bg, tm_x + (tm_y * 32))
                 } else {
                     todo!()