src/bus.rs

@@ -262,7 +262,6 @@ impl BusIo for Bus {
                     0x49 => self.ppu.monochrome.obj_palette_1.into(),
                     0x4A => self.ppu.pos.window_y,
                     0x4B => self.ppu.pos.window_x,
-                    0x4F => 0xFF, // CGB VRAM Bank Select
                     _ => {
                         warn!("Attempted read from {:#06X} on IO", addr);
                         0xFF
@@ -373,14 +372,12 @@ impl BusIo for Bus {
                     0x4A => self.ppu.pos.window_y = byte,
                     0x4B => self.ppu.pos.window_x = byte,
                     0x4D => {} // CGB Specific Register
-                    0x4F => {} // CGB VRAM Bank Select
                     0x50 => {
                         // Disable Boot ROM
                         if byte != 0 {
                             self.boot = None;
                         }
                     }
-                    0x70 => {} // CGB WRAM Bank Select
                     _ => warn!("Attempted write of {:#04X} to {:#06X} on IO", byte, addr),
                 };
             }

src/instruction.rs

@@ -334,6 +334,7 @@ impl Instruction {
             Instruction::ADD(target, src) => match (target, src) {
                 (AddTarget::HL, AddSource::Group1(pair)) => {
                     // ADD HL, r16 | Add 16-bit register to HL
+                    // FIXME: Memory Timings are not properly emulated for this instruction
                     use Group1RegisterPair::*;
                     let mut flags: Flags = *cpu.flags();
 
@@ -341,11 +342,10 @@ impl Instruction {
                         BC | DE | HL | SP => {
                             let left = cpu.register_pair(RegisterPair::HL);
                             let right = cpu.register_pair(pair.as_register_pair());
-                            let result = Self::add_u16(left, right, &mut flags);
-
-                            cpu.set_register(CpuRegister::L, result as u8);
-                            cpu.bus.clock();
-                            cpu.set_register(CpuRegister::H, (result >> 8) as u8);
+                            cpu.set_register_pair(
+                                RegisterPair::HL,
+                                Self::add_u16(left, right, &mut flags),
+                            );
                         }
                     }
                     cpu.set_flags(flags);
@@ -376,15 +376,12 @@ impl Instruction {
                 }
                 (AddTarget::SP, AddSource::ImmediateSignedByte) => {
                     // ADD SP, i8 | Add i8 to stack pointer
+                    // FIXME: Memory Timings are not properly emulated for this instruction
                     let mut flags: Flags = *cpu.flags();
 
                     let left = cpu.register_pair(RegisterPair::SP);
                     let sum = Self::add_u16_i8(left, Self::imm_byte(cpu) as i8, &mut flags);
-                    cpu.bus.clock(); // internal
-
                     cpu.set_register_pair(RegisterPair::SP, sum);
-                    cpu.bus.clock();
-
                     cpu.set_flags(flags);
                     16
                 }
@@ -426,6 +423,7 @@ impl Instruction {
                     AllRegisters::Group1(pair) => {
                         // INC r16 | Increment 16-bit register
                         // Note: No flags are set with this version of the INC instruction
+                        // FIXME: Memory Timings are not properly emulated for this instruction
                         use Group1RegisterPair::*;
 
                         match pair {
@@ -433,7 +431,6 @@ impl Instruction {
                                 let pair = pair.as_register_pair();
                                 let left = cpu.register_pair(pair);
                                 cpu.set_register_pair(pair, left.wrapping_add(1));
-                                cpu.bus.clock(); // internal
                             }
                         }
                         8
@@ -465,6 +462,7 @@ impl Instruction {
                     }
                     AllRegisters::Group1(pair) => {
                         // DEC r16 | Decrement Register Pair
+                        // FIXME: Memory Timings are not properly emulated for this instruction
                         use Group1RegisterPair::*;
 
                         match pair {
@@ -472,7 +470,6 @@ impl Instruction {
                                 let pair = pair.as_register_pair();
                                 let left = cpu.register_pair(pair);
                                 cpu.set_register_pair(pair, left.wrapping_sub(1));
-                                cpu.bus.clock(); // internal
                             }
                         };
                         8