Add complement A register instruction

src/cpu/instructions/misc.rs

@@ -4,4 +4,5 @@
 pub enum MiscInstruction {
     SetCarryFlag,
     ComplementCarryFlag,
+    ComplementARegister,
 }

src/cpu/parse/misc.rs

@@ -12,6 +12,7 @@ impl OpcodeParser for Parser {
         match opcode {
             0x37 => Ok(build_set_carry_flag_data()),
             0x3F => Ok(build_complement_carry_flag_data()),
+            0x2F => Ok(build_complement_a_register_data()),
             _ => Err(super::Error::UnknownOpcode(opcode)),
         }
     }
@@ -36,3 +37,13 @@ fn build_complement_carry_flag_data() -> ParseOutput {
         1,
     )
 }
+
+fn build_complement_a_register_data() -> ParseOutput {
+    (
+        RunnableInstruction {
+            instruction: Instruction::Misc(MiscInstruction::ComplementARegister),
+            cycles: 4,
+        },
+        1,
+    )
+}

src/cpu/run/misc.rs

@@ -16,6 +16,23 @@ impl Run for MiscInstruction {
 
                 set_flags_in_carry_bit_instruction(processor, flipped);
 
+                Ok(())
+            }
+            MiscInstruction::ComplementARegister => {
+                let current_value = processor
+                    .registers
+                    .get_single_8bit_register(register::SingleEightBit::A);
+                processor
+                    .registers
+                    .set_single_8bit_register(register::SingleEightBit::A, !current_value);
+
+                processor
+                    .registers
+                    .set_flag_bit(register::Flag::HalfCarry, 1);
+                processor
+                    .registers
+                    .set_flag_bit(register::Flag::Subtract, 1);
+
                 Ok(())
             }
         }
@@ -27,6 +44,10 @@ fn set_flags_in_carry_bit_instruction(processor: &mut Processor, carry_flag: u8)
         .registers
         .set_flag_bit(register::Flag::Carry, carry_flag);
 
-    processor.registers.set_flag_bit(register::Flag::HalfCarry, 0);
-    processor.registers.set_flag_bit(register::Flag::Subtract, 0);
+    processor
+        .registers
+        .set_flag_bit(register::Flag::HalfCarry, 0);
+    processor
+        .registers
+        .set_flag_bit(register::Flag::Subtract, 0);
 }

tests/cpu/misc.rs

@@ -1,9 +1,9 @@
+use crate::testutil;
 use ferris_boi::{
     cpu::{instructions::RunnableInstruction, Processor},
     register,
 };
 use test_case::test_case;
-use crate::testutil;
 
 #[test_case(1)]
 #[test_case(0)]
@@ -66,3 +66,42 @@ fn test_all_carry_bit_instructions_adjust_flags(opcode: u8) {
         (register::Flag::Zero, 1),
     );
 }
+
+#[test]
+fn test_complement_a_register_value() {
+    let mut processor = Processor::default();
+    processor.registers.a = 0xF0;
+
+    let data = [0x2F, 0x03];
+    let (ins, extra_data) =
+        RunnableInstruction::from_data(&data).expect("could not parse instruction");
+
+    assert_eq!(extra_data, &[0x03]);
+    processor.run_instruction(&ins);
+
+    assert_eq!(0x0F, processor.registers.a);
+}
+
+#[test]
+fn test_complement_a_register_flags() {
+    let mut processor = Processor::default();
+    processor.registers.a = 0xF0;
+    testutil::set_opposite_of_expected_flags(&mut processor, (0, 1, 1, 0));
+
+    let data = [0x2F, 0x03];
+    let (ins, extra_data) =
+        RunnableInstruction::from_data(&data).expect("could not parse instruction");
+
+    assert_eq!(extra_data, &[0x03]);
+    processor.run_instruction(&ins);
+
+    testutil::assert_flags_eq!(
+        processor,
+        // Always 1
+        (register::Flag::HalfCarry, 1),
+        (register::Flag::Subtract, 1),
+        // Value is preserved
+        (register::Flag::Carry, 1),
+        (register::Flag::Zero, 1),
+    );
+}