Add support for carry bit set instructions

src/cpu/instructions.rs

@@ -8,6 +8,7 @@ pub mod arith16;
 pub mod arith8;
 pub mod load16;
 pub mod load8;
+pub mod misc;
 
 // these are indexed with the instruction numbers in this manual
 // http://marc.rawer.de/Gameboy/Docs/GBCPUman.pdf
@@ -18,6 +19,7 @@ pub enum Instruction {
     EightBitArithmetic(arith8::EightBitArithmeticInstruction),
     StackPointerAdjust(arith8::AdjustStackPointerInstruction),
     SixteenBitArithmetic(arith16::SixteenBitArithmeticInstruction),
+    Misc(misc::MiscInstruction),
 }
 
 /// `RunnableInstruction` is an instruction that can run on the processor, and has any metadata needed to do so

src/cpu/instructions/load16.rs

@@ -28,6 +28,6 @@ pub enum SixteenBitLoadInstruction {
     },
 
     LoadStackPointerToImmediateAddress {
-        dst_address: u16
-    }
+        dst_address: u16,
+    },
 }

src/cpu/instructions/misc.rs

@@ -0,0 +1,7 @@
+//! The `misc` module holds instructions that I couldn't think of a better category for
+
+#[derive(Debug, Clone, Copy)]
+pub enum MiscInstruction {
+    SetCarryFlag,
+    ComplementCarryFlag,
+}

src/cpu/parse.rs

@@ -9,6 +9,7 @@ mod arith16;
 mod arith8;
 mod load16;
 mod load8;
+mod misc;
 
 #[derive(Error, Debug, Clone)]
 pub enum Error {
@@ -44,6 +45,7 @@ pub fn next_instruction(data: &View) -> ParseResult {
         load16::stack::Parser::parse_opcode,
         arith8::Parser::parse_opcode,
         arith16::Parser::parse_opcode,
+        misc::Parser::parse_opcode,
     ];
 
     for parse_func in parse_funcs {

src/cpu/parse/load16/stack.rs

@@ -1,7 +1,7 @@
 use crate::cpu::instructions::load16::SixteenBitLoadInstruction;
 use crate::cpu::instructions::{Instruction, RunnableInstruction};
 use crate::cpu::parse::{self, Error, OpcodeParser, ParseOutput, ParseResult};
-use crate::memory::{View, GetViewTuple};
+use crate::memory::{GetViewTuple, View};
 use crate::register;
 
 #[allow(clippy::module_name_repetitions)]
@@ -17,9 +17,7 @@ impl OpcodeParser for Parser {
     fn parse_opcode(data: &View) -> ParseResult {
         let opcode = parse::get_opcode_from_data(data);
         match opcode {
-            0x08 => Ok(make_load_sp_to_address_data(
-                data,
-            )),
+            0x08 => Ok(make_load_sp_to_address_data(data)),
             0xF5 => Ok(make_stack_operation_data(
                 Operation::Push,
                 register::Combined::AF,
@@ -81,10 +79,10 @@ fn make_load_sp_to_address_data(data: &View) -> ParseOutput {
     (
         RunnableInstruction {
             instruction: Instruction::SixteenBitLoad(
-                SixteenBitLoadInstruction::LoadStackPointerToImmediateAddress { dst_address }
+                SixteenBitLoadInstruction::LoadStackPointerToImmediateAddress { dst_address },
             ),
             cycles: 20,
         },
-        3
+        3,
     )
 }

src/cpu/parse/misc.rs

@@ -0,0 +1,38 @@
+use super::{OpcodeParser, ParseOutput, ParseResult};
+use crate::{
+    cpu::instructions::{misc::MiscInstruction, Instruction, RunnableInstruction},
+    memory::View,
+};
+
+pub struct Parser;
+
+impl OpcodeParser for Parser {
+    fn parse_opcode(data: &View) -> ParseResult {
+        let opcode = super::get_opcode_from_data(data);
+        match opcode {
+            0x37 => Ok(build_set_carry_flag_data()),
+            0x3F => Ok(build_complement_carry_flag_data()),
+            _ => Err(super::Error::UnknownOpcode(opcode)),
+        }
+    }
+}
+
+fn build_set_carry_flag_data() -> ParseOutput {
+    (
+        RunnableInstruction {
+            instruction: Instruction::Misc(MiscInstruction::SetCarryFlag),
+            cycles: 4,
+        },
+        1,
+    )
+}
+
+fn build_complement_carry_flag_data() -> ParseOutput {
+    (
+        RunnableInstruction {
+            instruction: Instruction::Misc(MiscInstruction::ComplementCarryFlag),
+            cycles: 4,
+        },
+        1,
+    )
+}

src/cpu/run.rs

@@ -9,6 +9,7 @@ mod arith8;
 mod arithutil;
 mod load16;
 mod load8;
+mod misc;
 
 /// `Error` represents a run error. Typically these will be fatal and panicking on their emission
 /// is likely the best course of action
@@ -41,5 +42,6 @@ pub fn run_instruction(processor: &mut Processor, instruction: Instruction) -> R
         Instruction::EightBitArithmetic(arith_instruction) => arith_instruction.run_on(processor),
         Instruction::StackPointerAdjust(adjust_instruction) => adjust_instruction.run_on(processor),
         Instruction::SixteenBitArithmetic(arith_instruction) => arith_instruction.run_on(processor),
+        Instruction::Misc(instruction) => instruction.run_on(processor),
     }
 }

src/cpu/run/load16.rs

@@ -113,19 +113,17 @@ impl Run for SixteenBitLoadInstruction {
                 );
 
                 Ok(())
-            },
+            }
             SixteenBitLoadInstruction::LoadStackPointerToImmediateAddress { dst_address } => {
                 let current_sp = processor
                     .registers
                     .get_single_16bit_register(register::SingleSixteenBit::StackPointer);
 
                 let [top_half, bottom_half] = current_sp.to_be_bytes();
-                let memory_res = processor.memory.set_both(
-                    (
+                let memory_res = processor.memory.set_both((
                     (usize::from(dst_address), bottom_half),
                     (usize::from(dst_address + 1), top_half),
-                    )
-                );
+                ));
 
                 match memory_res {
                     Ok(_) => Ok(()),

src/cpu/run/load8.rs

@@ -130,7 +130,7 @@ impl Run for EightBitLoadInstruction {
             } => {
                 let src_address = memory::IO_REGISTER_START_ADDRESS + usize::from(offset);
                 processor.load_from_address_to_register(dst, src_address)
-            },
+            }
         }
     }
 }

src/cpu/run/misc.rs

@@ -0,0 +1,32 @@
+use crate::cpu::{instructions::misc::MiscInstruction, register, run::Error, Processor};
+
+use super::Run;
+
+impl Run for MiscInstruction {
+    fn run_on(&self, processor: &mut Processor) -> Result<(), Error> {
+        match *self {
+            MiscInstruction::SetCarryFlag => {
+                set_flags_in_carry_bit_instruction(processor, 1);
+
+                Ok(())
+            }
+            MiscInstruction::ComplementCarryFlag => {
+                let current_carry_flag = processor.registers.get_flag_bit(register::Flag::Carry);
+                let flipped = (current_carry_flag == 0).into();
+
+                set_flags_in_carry_bit_instruction(processor, flipped);
+
+                Ok(())
+            }
+        }
+    }
+}
+
+fn set_flags_in_carry_bit_instruction(processor: &mut Processor, carry_flag: u8) {
+    processor
+        .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);
+}

tests/cpu/main.rs

@@ -3,4 +3,5 @@ mod arith8;
 mod jsmoo;
 mod load16;
 mod load8;
+mod misc;
 mod testutil;

tests/cpu/misc.rs

@@ -0,0 +1,68 @@
+use ferris_boi::{
+    cpu::{instructions::RunnableInstruction, Processor},
+    register,
+};
+use test_case::test_case;
+use crate::testutil;
+
+#[test_case(1)]
+#[test_case(0)]
+fn test_set_carry_flag_always_sets_to_1(starting_value: u8) {
+    let mut processor = Processor::default();
+    processor
+        .registers
+        .set_flag_bit(register::Flag::Carry, starting_value);
+
+    let data = [0x37, 0x03];
+    let (ins, extra_data) =
+        RunnableInstruction::from_data(&data).expect("could not parse instruction");
+
+    assert_eq!(extra_data, &[0x03]);
+    processor.run_instruction(&ins);
+
+    let new_carry_bit = processor.registers.get_flag_bit(register::Flag::Carry);
+    assert_eq!(1, new_carry_bit);
+}
+
+#[test_case(1, 0)]
+#[test_case(0, 1)]
+fn test_complement_carry_bit(starting_value: u8, expected_value: u8) {
+    let mut processor = Processor::default();
+    processor
+        .registers
+        .set_flag_bit(register::Flag::Carry, starting_value);
+
+    let data = [0x3F, 0x03];
+    let (ins, extra_data) =
+        RunnableInstruction::from_data(&data).expect("could not parse instruction");
+
+    assert_eq!(extra_data, &[0x03]);
+    processor.run_instruction(&ins);
+
+    let new_carry_bit = processor.registers.get_flag_bit(register::Flag::Carry);
+    assert_eq!(expected_value, new_carry_bit);
+}
+
+#[test_case(0x37)]
+#[test_case(0x3F)]
+fn test_all_carry_bit_instructions_adjust_flags(opcode: u8) {
+    let mut processor = Processor::default();
+    testutil::set_opposite_of_expected_flags(&mut processor, (0, 0, 0, 1));
+
+    let data = [opcode, 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 zero
+        (register::Flag::HalfCarry, 0),
+        (register::Flag::Carry, 1),
+        (register::Flag::Subtract, 0),
+        // Value is preserved
+        (register::Flag::Zero, 1),
+    );
+}