Fix: OAMADDx address is a word address, not a byte address

twvd · Dec 9, 2023 · 131685b · 131685b
1 parent 656a7ce
commit 131685b
Show file tree

Hide file tree

Showing 2 changed files with 12 additions and 11 deletions.
diff --git a/src/snes/ppu/bus.rs b/src/snes/ppu/bus.rs
@@ -141,18 +141,18 @@ where
                 0x2101 => Some(self.obsel = val),
                 // OAMADDL - OAM Address and Priority Rotation (W)
                 0x2102 => {
-                    let v = self.oamadd.get() & 0xFF00;
-                    Some(self.oamadd.set(v | val as u16))
+                    let v = (self.oamadd.get() >> 1) & 0xFF00;
+                    Some(self.oamadd.set((v | val as u16) << 1))
                 }
                 // OAMADDH - OAM Address and Priority Rotation (W)
                 0x2103 => {
-                    let v = self.oamadd.get() & 0x00FF;
+                    let v = (self.oamadd.get() >> 1) & 0x00FF;
                     let val = val & 0x83; // bit 10-14 unused
                     if val & 0x80 != 0 {
                         // Obj priority
                         // TODO
                     }
-                    Some(self.oamadd.set(v | (val as u16) << 8))
+                    Some(self.oamadd.set((v | (val as u16) << 8) << 1))
                 }
                 // OAMDATA - OAM Data Write (W)
                 0x2104 => {

diff --git a/src/snes/ppu/tests.rs b/src/snes/ppu/tests.rs
@@ -201,8 +201,8 @@ fn oam_write_seq() {
     assert_eq!(p.oam[0..5], [0xAA, 0xBB, 0xCC, 0xDD, 0]);
 
     // Test end of OAM towards the 32 byte extension table
-    p.write(0x2102, (510 & 0xFF) as u8);
-    p.write(0x2103, (510 >> 8) as u8);
+    p.write(0x2102, ((510 >> 1) & 0xFF) as u8);
+    p.write(0x2103, ((510 >> 1) >> 8) as u8);
     assert_eq!(p.oam[510..513], [0, 0, 0]);
     p.write(0x2104, 0xAA);
     assert_eq!(p.oam[510..513], [0, 0, 0]);
@@ -216,8 +216,8 @@ fn oam_write_seq() {
 fn oam_write_exttable() {
     let mut p = ppu();
     assert_eq!(p.oam[512], 0);
-    p.write(0x2102, (512 & 0xFF) as u8);
-    p.write(0x2103, (512 >> 8) as u8);
+    p.write(0x2102, ((512 >> 1) & 0xFF) as u8);
+    p.write(0x2103, ((512 >> 1) >> 8) as u8);
     p.write(0x2104, 0xAA);
     assert_eq!(p.oam[512], 0xAA);
 }
@@ -226,8 +226,8 @@ fn oam_write_exttable() {
 fn oam_write_exttable_mirror() {
     let mut p = ppu();
     assert_eq!(p.oam[512], 0);
-    p.write(0x2102, (0x220 & 0xFF) as u8);
-    p.write(0x2103, (0x220 >> 8) as u8);
+    p.write(0x2102, (0x120 & 0xFF) as u8);
+    p.write(0x2103, (0x120 >> 8) as u8);
     p.write(0x2104, 0xAA);
     assert_eq!(p.oam[512], 0xAA);
 }
@@ -250,8 +250,9 @@ fn oam_read() {
     p.oam[3] = 1;
     p.oam[4] = 2;
     p.oam[5] = 3;
-    p.write(0x2102, 3);
+    p.write(0x2102, 3 >> 1);
     p.write(0x2103, 0);
+    assert_eq!(p.read(0x2138), Some(0));
     assert_eq!(p.read(0x2138), Some(1));
     assert_eq!(p.read(0x2138), Some(2));
     assert_eq!(p.read(0x2138), Some(3));