src/bus/io.zig

@@ -29,7 +29,7 @@ pub const Io = struct {
 
     pub fn write16(self: *@This(), addr: u32, halfword: u16) void {
         switch (addr) {
-            0x0400_0000 => self.dispcnt.val = halfword,
+            0x0400_000 => self.dispcnt.val = halfword,
             else => std.debug.panic("[I/O:16] tried to write 0x{X:} to 0x{X:}", .{ halfword, addr }),
         }
     }

src/cpu/half_signed_data_transfer.zig

@@ -51,7 +51,10 @@ pub fn comptimeHalfSignedDataTransfer(comptime P: bool, comptime U: bool, compti
             } else {
                 if (opcode >> 5 & 0x01 == 0x01) {
                     // STRH
-                    bus.write16(address, @truncate(u16, cpu.r[rd]));
+                    const src = @truncate(u16, cpu.r[rd]);
+
+                    bus.write16(address + 2, src);
+                    bus.write16(address, src);
                 } else {
                     std.debug.panic("[CPU] TODO: Figure out if this is also SWP", .{});
                 }

src/cpu/single_data_transfer.zig

@@ -31,11 +31,19 @@ pub fn comptimeSingleDataTransfer(comptime I: bool, comptime P: bool, comptime U
             } else {
                 if (B) {
                     // STRB
-                    bus.write8(address, @truncate(u8, cpu.r[rd]));
+                    const src = @truncate(u8, cpu.r[rd]);
+
+                    bus.write8(address + 3, src);
+                    bus.write8(address + 2, src);
+                    bus.write8(address + 1, src);
+                    bus.write8(address, src);
                 } else {
                     // STR
-                    const force_aligned = address & 0xFFFF_FFFC;
-                    bus.write32(force_aligned, cpu.r[rd]);
+
+                    // FIXME: Is this right?
+                    const src = cpu.r[rd];
+                    const aligned_addr = address - (address % 4);
+                    bus.write32(aligned_addr, src);
                 }
             }