use super::cpu::{Cpu, Flags, Register, RegisterPair}; use std::convert::TryFrom; #[derive(Debug, Copy, Clone)] pub enum Instruction { NOP, LD(LDTarget, LDTarget), STOP, JR(JumpCondition, i8), ADD(MATHTarget, MATHTarget), INC(Registers), DEC(Registers), RLCA, RRCA, RLA, RRA, DAA, CPL, SCF, CCF, HALT, ADC(MATHTarget, MATHTarget), SUB(MATHTarget), // SUB A, MATHTarget always SBC(MATHTarget, MATHTarget), AND(MATHTarget), // AND A, MATHTarget always XOR(MATHTarget), // XOR A, MATHTarget always OR(MATHTarget), // OR A, MATHTarget always CP(MATHTarget), // CP A, MATHTarget always RET(JumpCondition), LDHL(i8), // LD HL, SP + d POP(RegisterPair), RETI, JP(JumpCondition, JPTarget), DI, EI, CALL(JumpCondition, u16), PUSH(RegisterPair), RST(u8), } #[derive(Debug, Copy, Clone)] pub struct Cycles(u8); impl Instruction { pub fn execute(cpu: &mut Cpu, instruction: Self) -> Cycles { match instruction { Instruction::NOP => Cycles(4), Instruction::LD(lhs, rhs) => match (lhs, rhs) { (LDTarget::ByteAtAddress(nn), LDTarget::RegisterPair(RegisterPair::SP)) => { // LD (nn), SP | Put Stack Pointer at address nn cpu.write_word(nn, cpu.register_pair(RegisterPair::SP)); Cycles(20) } (LDTarget::RegisterPair(pair), LDTarget::ImmediateWord(nn)) => { // LD rp[p], nn | Put value nn into register pair match pair { RegisterPair::BC | RegisterPair::DE | RegisterPair::HL | RegisterPair::SP => { cpu.set_register_pair(RegisterPair::try_from(pair).unwrap(), nn) } _ => unreachable!(), } Cycles(12) } (LDTarget::IndirectRegister(pair), LDTarget::Register(InstrRegister::A)) => { let a = cpu.register(Register::A); match pair { InstrRegisterPair::BC | InstrRegisterPair::DE => { // LD (BC), A | Put A into memory address BC // LD (DE), A | Put A into memory address DE let addr = cpu.register_pair(RegisterPair::try_from(pair).unwrap()); cpu.write_byte(addr, a); } InstrRegisterPair::IncrementHL => { // LD (HL+), A | Put A into memory address HL, then increment HL let addr = cpu.register_pair(RegisterPair::HL); cpu.write_byte(addr, a); cpu.set_register_pair(RegisterPair::HL, addr + 1); } InstrRegisterPair::DecrementHL => { // LD (HL-), A | Put A into memory address HL, then decrement HL let addr = cpu.register_pair(RegisterPair::HL); cpu.write_byte(addr, a); cpu.set_register_pair(RegisterPair::HL, addr - 1); } _ => unreachable!(), } Cycles(8) } (LDTarget::Register(InstrRegister::A), LDTarget::IndirectRegister(pair)) => { match pair { InstrRegisterPair::BC | InstrRegisterPair::DE => { // LD A, (BC) | Put value at address BC into A // LD A, (DE) | Put value at address DE into A let addr = cpu.register_pair(RegisterPair::try_from(pair).unwrap()); cpu.set_register(Register::A, cpu.read_byte(addr)); } InstrRegisterPair::IncrementHL => { // LD A, (HL+) | Put value at address HL into A, then increment HL let addr = cpu.register_pair(RegisterPair::HL); cpu.set_register(Register::A, cpu.read_byte(addr)); cpu.set_register_pair(RegisterPair::HL, addr + 1); } InstrRegisterPair::DecrementHL => { // LD A, (HL-) | Put value at address HL into A, then increment HL let addr = cpu.register_pair(RegisterPair::HL); cpu.set_register(Register::A, cpu.read_byte(addr)); cpu.set_register_pair(RegisterPair::HL, addr - 1); } _ => unreachable!(), } Cycles(8) } (LDTarget::Register(reg), LDTarget::ImmediateByte(n)) => { // LD r[y], n | Store n in Register match reg { InstrRegister::IndirectHL => { let addr = cpu.register_pair(RegisterPair::HL); cpu.write_byte(addr, n); Cycles(12) } InstrRegister::A | InstrRegister::B | InstrRegister::C | InstrRegister::D | InstrRegister::E | InstrRegister::H | InstrRegister::L => { cpu.set_register(Register::try_from(reg).unwrap(), n); Cycles(8) } InstrRegister::IndirectC => unreachable!(), } } (LDTarget::Register(lhs), LDTarget::Register(rhs)) => unimplemented!(), _ => unimplemented!(), }, Instruction::STOP => Cycles(4), Instruction::JR(cond, offset) => { // JR cc[y - 4], d | If condition is true, then add d to current address and jump // JR d | Add d to current address and jump let prev = cpu.register_pair(RegisterPair::PC); let flags: Flags = cpu.register(Register::Flag).into(); let new_address = (prev as i16 + offset as i16) as u16; match cond { JumpCondition::Always => { cpu.set_register_pair(RegisterPair::PC, new_address); Cycles(12) } JumpCondition::NotZero => { if !flags.z { cpu.set_register_pair(RegisterPair::PC, new_address); return Cycles(12); } Cycles(8) } JumpCondition::Zero => { if flags.z { cpu.set_register_pair(RegisterPair::PC, new_address); return Cycles(12); } Cycles(8) } JumpCondition::NotCarry => { if !flags.c { cpu.set_register_pair(RegisterPair::PC, new_address); return Cycles(12); } Cycles(8) } JumpCondition::Carry => { if flags.c { cpu.set_register_pair(RegisterPair::PC, new_address); return Cycles(12); } Cycles(8) } } } Instruction::ADD(lhs, rhs) => match (lhs, rhs) { (MATHTarget::RegisterPair(RegisterPair::HL), MATHTarget::RegisterPair(pair)) => { // ADD HL, rp[p] | add register pair to HL. let mut flags: Flags = cpu.register(Register::Flag).into(); match pair { RegisterPair::BC | RegisterPair::DE | RegisterPair::HL | RegisterPair::SP => { let hl_value = cpu.register_pair(RegisterPair::HL); let value = cpu.register_pair(RegisterPair::try_from(pair).unwrap()); let sum = Self::add_u16s(hl_value, value, &mut flags); cpu.set_register_pair(RegisterPair::HL, sum); } _ => unreachable!(), } cpu.set_register(Register::Flag, flags.into()); Cycles(8) } _ => unimplemented!(), }, Instruction::INC(Registers::Word(pair)) => { // INC rp[p] | Increment Register Pair match pair { RegisterPair::BC | RegisterPair::DE | RegisterPair::HL | RegisterPair::SP => { let value = cpu.register_pair(pair); cpu.set_register_pair(pair, value + 1); } _ => unreachable!(), } Cycles(8) } Instruction::INC(Registers::Byte(reg)) => { // INC r[y] | Increment Register let mut flags: Flags = cpu.register(Register::Flag).into(); let cycles: Cycles; match reg { InstrRegister::B | InstrRegister::C | InstrRegister::D | InstrRegister::E | InstrRegister::H | InstrRegister::L | InstrRegister::A => { let reg = Register::try_from(reg).unwrap(); let value = cpu.register(reg); cpu.set_register(reg, Self::inc_register(value, &mut flags)); cycles = Cycles(4) } InstrRegister::IndirectHL => { let addr = cpu.register_pair(RegisterPair::HL); cpu.write_byte(addr, Self::inc_register(cpu.read_byte(addr), &mut flags)); cycles = Cycles(12) } InstrRegister::IndirectC => unreachable!(), } cpu.set_register(Register::Flag, flags.into()); cycles } Instruction::DEC(Registers::Word(pair)) => { match pair { RegisterPair::BC | RegisterPair::DE | RegisterPair::HL | RegisterPair::SP => { let value = cpu.register_pair(pair); cpu.set_register_pair(pair, value - 1); } _ => unreachable!(), } Cycles(8) } Instruction::DEC(Registers::Byte(reg)) => { // DEC r[y] | Decrement Register let mut flags: Flags = cpu.register(Register::Flag).into(); let cycles: Cycles; match reg { InstrRegister::B | InstrRegister::C | InstrRegister::D | InstrRegister::E | InstrRegister::H | InstrRegister::L | InstrRegister::A => { let reg = Register::try_from(reg).unwrap(); let value = cpu.register(reg); cpu.set_register(reg, Self::dec_register(value, &mut flags)); cycles = Cycles(4); } InstrRegister::IndirectHL => { let addr = cpu.register_pair(RegisterPair::HL); cpu.write_byte(addr, Self::dec_register(cpu.read_byte(addr), &mut flags)); cycles = Cycles(12); } InstrRegister::IndirectC => unreachable!(), } cpu.set_register(Register::Flag, flags.into()); cycles } Instruction::RLCA => { let mut flags: Flags = cpu.register(Register::Flag).into(); let a = cpu.register(Register::A); let cache = a >> 7; // get the 7th bit (this will be the carry bit + the one that is wrapped around) let rot_a = (a << 1) | (cache << 0); // (rotate a left), then set the first bit (which will be a 0 by default) flags.z = false; flags.n = false; flags.h = false; flags.c = cache == 0x01; cpu.set_register(Register::Flag, flags.into()); cpu.set_register(Register::A, rot_a); Cycles(4) } Instruction::RRCA => { let mut flags: Flags = cpu.register(Register::Flag).into(); let a = cpu.register(Register::A); let cache = a & 0x01; // RLCA but the other way around let rot_a = (a >> 1) | (cache << 7); flags.z = false; flags.n = false; flags.h = false; flags.c = cache == 0x01; cpu.set_register(Register::Flag, flags.into()); cpu.set_register(Register::A, rot_a); Cycles(4) } Instruction::RLA => { let mut flags: Flags = cpu.register(Register::Flag).into(); let a = cpu.register(Register::A); let cache = a >> 7; let rot_a = (a << 1) | ((flags.c as u8) << 0); flags.z = false; flags.n = false; flags.h = false; flags.c = cache == 0x01; cpu.set_register(Register::Flag, flags.into()); cpu.set_register(Register::A, rot_a); Cycles(4) } Instruction::RRA => { let mut flags: Flags = cpu.register(Register::Flag).into(); let a = cpu.register(Register::A); let cache = a & 0x01; let rot_a = (a >> 1) | ((flags.c as u8) << 7); flags.z = false; flags.n = false; flags.h = false; flags.c = cache == 0x01; cpu.set_register(Register::Flag, flags.into()); cpu.set_register(Register::A, rot_a); Cycles(4) } Instruction::DAA => unimplemented!(), Instruction::CPL => { let mut flags: Flags = cpu.register(Register::Flag).into(); let a = cpu.register(Register::A); flags.n = true; flags.h = true; cpu.set_register(Register::Flag, flags.into()); cpu.set_register(Register::A, !a); // Bitwise not is ! instead of ~ Cycles(4) } Instruction::SCF => { let mut flags: Flags = cpu.register(Register::Flag).into(); flags.n = false; flags.h = false; flags.c = true; cpu.set_register(Register::Flag, flags.into()); Cycles(4) } Instruction::CCF => { let mut flags: Flags = cpu.register(Register::Flag).into(); flags.n = false; flags.h = false; flags.c = !flags.c; cpu.set_register(Register::Flag, flags.into()); Cycles(4) } _ => unimplemented!(), } } fn dec_register(reg: u8, flags: &mut Flags) -> u8 { let res = reg - 1; flags.z = res == 0; flags.n = true; flags.h = !Self::u8_half_carry(res, 1); // FIXME: Is this right? res } fn inc_register(reg: u8, flags: &mut Flags) -> u8 { let res = reg + 1; flags.z = res == 0; flags.n = false; flags.h = Self::u8_half_carry(reg, 1); res } fn add_u16s(left: u16, right: u16, flags: &mut Flags) -> u16 { let (sum, did_overflow) = left.overflowing_add(right); flags.n = false; flags.h = Self::u16_half_carry(left, right); flags.c = did_overflow; sum } fn u16_half_carry(left: u16, right: u16) -> bool { Self::u8_half_carry((left >> 8) as u8, (right >> 8) as u8) } fn u8_half_carry(left: u8, right: u8) -> bool { ((left & 0xF) + (right & 0xF)) & 0x10 == 0x10 } } impl Instruction { pub fn from_byte(cpu: &Cpu, byte: u8) -> Self { if byte == 0xCB { Self::from_prefixed_byte(cpu, byte) } else { Self::from_unprefixed_byte(cpu, byte) } } fn from_prefixed_byte(cpu: &Cpu, opcode: u8) -> Self { // https://gb-archive.github.io/salvage/decoding_gbz80_opcodes/Decoding%20Gamboy%20Z80%20Opcodes.html let x = (opcode >> 6) & 0b00000011; let y = (opcode >> 3) & 0b00000111; let z = opcode & 0b00000111; let p = y >> 1; let q = y & 0b00000001; let n = cpu.read_byte(cpu.register_pair(RegisterPair::PC) + 1); let nn = cpu.read_word(cpu.register_pair(RegisterPair::PC) + 1); match (x, z, q, y, p) { (0, 0, _, 0, _) => Instruction::NOP, // NOP (0, 0, _, 1, _) => Instruction::LD( // LD (nn), SP LDTarget::ByteAtAddress(nn), LDTarget::RegisterPair(RegisterPair::SP), ), (0, 0, _, 2, _) => Instruction::STOP, // STOP (0, 0, _, 3, _) => Instruction::JR(JumpCondition::Always, n as i8), // JR d (0, 0, _, 4..=7, _) => Instruction::JR(Table::cc(y - 4), n as i8), // JR cc[y - 4], d (0, 1, 0, _, _) => Instruction::LD( // LD rp[p], nn LDTarget::RegisterPair(Table::rp(p)), LDTarget::ImmediateWord(nn), ), (0, 1, 1, _, _) => Instruction::ADD( // ADD HL, rp[p] MATHTarget::HL, MATHTarget::RegisterPair(Table::rp(p)), ), (0, 2, 0, _, 0) => Instruction::LD( // LD (BC), A LDTarget::IndirectRegister(InstrRegisterPair::BC), LDTarget::Register(InstrRegister::A), ), (0, 2, 0, _, 1) => Instruction::LD( // LD (DE), A LDTarget::IndirectRegister(InstrRegisterPair::DE), LDTarget::Register(InstrRegister::A), ), (0, 2, 1, _, 0) => Instruction::LD( // LD A, (BC) LDTarget::Register(InstrRegister::A), LDTarget::IndirectRegister(InstrRegisterPair::BC), ), (0, 2, 1, _, 1) => Instruction::LD( // LD A, (DE) LDTarget::Register(InstrRegister::A), LDTarget::IndirectRegister(InstrRegisterPair::DE), ), (0, 2, 0, _, 2) => Instruction::LD( // LD (HL+), A LDTarget::IndirectRegister(InstrRegisterPair::IncrementHL), LDTarget::Register(InstrRegister::A), ), (0, 2, 0, _, 3) => Instruction::LD( // LD (HL-), A LDTarget::IndirectRegister(InstrRegisterPair::DecrementHL), LDTarget::Register(InstrRegister::A), ), (0, 2, 1, _, 2) => Instruction::LD( // LD A, (HL+) LDTarget::Register(InstrRegister::A), LDTarget::IndirectRegister(InstrRegisterPair::IncrementHL), ), (0, 2, 1, _, 3) => Instruction::LD( // LD A, (HL-) LDTarget::Register(InstrRegister::A), LDTarget::IndirectRegister(InstrRegisterPair::DecrementHL), ), (0, 3, 0, _, _) => Instruction::INC( // INC rp[p] Registers::Word(Table::rp(p)), ), (0, 3, 1, _, _) => Instruction::DEC( // DEC rp[p] Registers::Word(Table::rp(p)), ), (0, 4, _, _, _) => Instruction::INC( // INC r[y] Registers::Byte(Table::r(y)), ), (0, 5, _, _, _) => Instruction::DEC( // DEC r[y] Registers::Byte(Table::r(y)), ), (0, 6, _, _, _) => Instruction::LD( // LD r[y], n LDTarget::Register(Table::r(y)), LDTarget::ImmediateByte(n), ), (0, 7, _, 0, _) => Instruction::RLCA, (0, 7, _, 1, _) => Instruction::RRCA, (0, 7, _, 2, _) => Instruction::RLA, (0, 7, _, 3, _) => Instruction::RRA, (0, 7, _, 4, _) => Instruction::DAA, (0, 7, _, 5, _) => Instruction::CPL, (0, 7, _, 6, _) => Instruction::SCF, (0, 7, _, 7, _) => Instruction::CCF, (1, 6, _, 6, _) => Instruction::HALT, (1, _, _, _, _) => Instruction::LD( // LD r[y], r[z] LDTarget::Register(Table::r(y)), LDTarget::Register(Table::r(z)), ), (2, _, _, _, _) => Table::x2_alu(y, z), // alu[y] r[z] (3, 0, _, 0..=3, _) => Instruction::RET(Table::cc(y)), // RET cc[y] (3, 0, _, 4, _) => Instruction::LD( // LD (0xFF00 + n), A LDTarget::ByteAtAddress(0xFF00 + (n as u16)), // TODO: Do we want to do any calculations here? LDTarget::Register(InstrRegister::A), ), (3, 0, _, 5, _) => Instruction::ADD( // ADD SP, d MATHTarget::RegisterPair(RegisterPair::SP), MATHTarget::ImmediateByte(n), ), (3, 0, _, 6, _) => Instruction::LD( // LD A, (0xFF00 + n) LDTarget::Register(InstrRegister::A), LDTarget::ByteAtAddress(0xFF00 + (n as u16)), // TODO: DO we want to do any calculations here? ), (3, 0, _, 7, _) => Instruction::LDHL(n as i8), // LD HL, SP + d (3, 1, 0, _, _) => Instruction::POP(Table::rp2(p)), // POP rp2[p] (3, 1, 1, _, 0) => Instruction::RET(JumpCondition::Always), // RET (3, 1, 1, _, 1) => Instruction::RETI, (3, 1, 1, _, 2) => Instruction::JP( // JP HL JumpCondition::Always, JPTarget::RegisterPair(RegisterPair::HL), ), (3, 1, 1, _, 3) => Instruction::LD( // LD SP, HL LDTarget::RegisterPair(RegisterPair::SP), LDTarget::RegisterPair(RegisterPair::HL), ), (3, 2, _, 0..=3, _) => Instruction::JP( // JP cc[y], nn Table::cc(y), JPTarget::ImmediateWord(nn), ), (3, 2, _, 4, _) => Instruction::LD( // LD (0xFF00 + C) ,A LDTarget::Register(InstrRegister::IndirectC), LDTarget::Register(InstrRegister::A), ), (3, 2, _, 5, _) => Instruction::LD( // LD (nn), A LDTarget::ByteAtAddress(nn), LDTarget::Register(InstrRegister::A), ), (3, 2, _, 6, _) => Instruction::LD( // LD A, (0xFF00 + C) LDTarget::Register(InstrRegister::A), LDTarget::Register(InstrRegister::IndirectC), ), (3, 2, _, 7, _) => Instruction::LD( // LD A, (nn) LDTarget::Register(InstrRegister::A), LDTarget::ByteAtAddress(nn), ), (3, 3, _, 0, _) => Instruction::JP( // JP nn JumpCondition::Always, JPTarget::ImmediateWord(nn), ), (3, 3, _, 1, _) => unreachable!("This is the 0xCB Prefix"), // (3, 3, _, 2, _) => unreachable!(), (removed in documentation) // (3, 3, _, 3, _) => unimplemented!(), (removed in documentation) // (3, 3, _, 4, _) => unimplemented!(), (removed in documentation) // (3, 3, _, 5, _) => unimplemented!(), (removed in documentation) (3, 3, _, 6, _) => Instruction::DI, (3, 3, _, 7, _) => Instruction::EI, (3, 4, _, 0..=3, _) => Instruction::CALL(Table::cc(y), nn), // CALL cc[y], nn // (3, 4, _, 4..=7, _) => unimplemented!(), (removed in documentation) (3, 5, 0, _, _) => Instruction::PUSH(Table::rp2(p)), // PUSH rp2[p] (3, 5, 1, _, 0) => Instruction::CALL(JumpCondition::Always, nn), // CALL nn // (3, 5, 1, _, 1..=3) => unimplemented!(), (removed in documentation) (3, 6, _, _, _) => Table::x3_alu(y, n), (3, 7, _, _, _) => Instruction::RST(y * 8), // RST y * 8 _ => unimplemented!( "Unknown Opcode: {:#?}\n x: {}, z: {}, q: {}, y: {}, p: {}", opcode, x, z, q, y, p ), } } fn from_unprefixed_byte(cpu: &Cpu, byte: u8) -> Self { unimplemented!() } } #[derive(Debug, Copy, Clone)] pub enum JPTarget { RegisterPair(RegisterPair), ImmediateWord(u16), } #[derive(Debug, Copy, Clone)] pub enum Registers { Byte(InstrRegister), Word(RegisterPair), } #[derive(Debug, Copy, Clone)] pub enum MATHTarget { HL, SP, Register(InstrRegister), RegisterPair(RegisterPair), ImmediateByte(u8), } #[derive(Debug, Copy, Clone)] pub enum LDTarget { Register(InstrRegister), IndirectRegister(InstrRegisterPair), ByteAtAddress(u16), ImmediateWord(u16), ImmediateByte(u8), RegisterPair(RegisterPair), } #[derive(Debug, Copy, Clone)] enum InstrRegisterPair { AF, BC, DE, HL, SP, PC, IncrementHL, DecrementHL, } impl From for InstrRegisterPair { fn from(pair: RegisterPair) -> Self { match pair { RegisterPair::AF => Self::AF, RegisterPair::BC => Self::BC, RegisterPair::DE => Self::DE, RegisterPair::HL => Self::HL, RegisterPair::SP => Self::SP, RegisterPair::PC => Self::PC, } } } impl TryFrom for RegisterPair { type Error = String; // FIXME: Proper error type goes here. fn try_from(pair: InstrRegisterPair) -> Result { match pair { InstrRegisterPair::AF => Ok(Self::AF), InstrRegisterPair::BC => Ok(Self::BC), InstrRegisterPair::DE => Ok(Self::DE), InstrRegisterPair::HL => Ok(Self::HL), InstrRegisterPair::SP => Ok(Self::SP), InstrRegisterPair::PC => Ok(Self::PC), InstrRegisterPair::IncrementHL => { Err("Can not convert InstrRegisterPair::IncrementHL to RegisterPair".to_string()) } InstrRegisterPair::DecrementHL => { Err("Can not convert InstrRegisterPair::DecrementHL to RegisterPair".to_string()) } } } } #[derive(Debug, Copy, Clone)] enum InstrRegister { A, B, C, D, E, H, L, IndirectHL, // (HL) IndirectC, // (0xFF00 + C) } impl TryFrom for InstrRegister { type Error = String; // FIXME: Proper error type goes here fn try_from(register: Register) -> Result { match register { Register::A => Ok(Self::A), Register::B => Ok(Self::B), Register::C => Ok(Self::C), Register::D => Ok(Self::D), Register::E => Ok(Self::E), Register::H => Ok(Self::H), Register::L => Ok(Self::L), Register::Flag => Err("Can not convert Register::Flag to InstrRegister".to_string()), } } } impl TryFrom for Register { type Error = String; // FIXME: Proper error type goes here. fn try_from(register: InstrRegister) -> Result { match register { InstrRegister::A => Ok(Self::A), InstrRegister::B => Ok(Self::B), InstrRegister::C => Ok(Self::C), InstrRegister::D => Ok(Self::D), InstrRegister::E => Ok(Self::E), InstrRegister::H => Ok(Self::H), InstrRegister::L => Ok(Self::L), InstrRegister::IndirectHL => { Err("Can not convert InstrRegister::IndirectHL to Register".to_string()) } InstrRegister::IndirectC => { Err("Can not convert InstrRegister::IndirectC to Register".to_string()) } } } } #[derive(Debug, Copy, Clone)] pub enum JumpCondition { NotZero, Zero, NotCarry, Carry, Always, } #[derive(Debug, Copy, Clone)] struct Table; impl Table { pub fn r(index: u8) -> InstrRegister { match index { 0 => InstrRegister::B, 1 => InstrRegister::C, 2 => InstrRegister::D, 3 => InstrRegister::E, 4 => InstrRegister::H, 5 => InstrRegister::L, 6 => InstrRegister::IndirectHL, 7 => InstrRegister::A, _ => unreachable!("Index {} is out of bounds in r[]", index), } } pub fn rp2(index: u8) -> RegisterPair { match index { 0 => RegisterPair::BC, 1 => RegisterPair::DE, 2 => RegisterPair::HL, 3 => RegisterPair::AF, _ => unreachable!("Index {} out of bounds in rp2[]", index), } } pub fn rp(index: u8) -> RegisterPair { match index { 0 => RegisterPair::BC, 1 => RegisterPair::DE, 2 => RegisterPair::HL, 3 => RegisterPair::SP, _ => unreachable!("Index {} out of bounds in rp[]", index), } } pub fn cc(index: u8) -> JumpCondition { match index { 0 => JumpCondition::NotZero, 1 => JumpCondition::Zero, 2 => JumpCondition::NotCarry, 3 => JumpCondition::Carry, _ => unreachable!("Index {} out of bounds in cc[]", index), } } pub fn x2_alu(fn_index: u8, r_index: u8) -> Instruction { match fn_index { 0 => Instruction::ADD( // ADD A, r[z] MATHTarget::Register(InstrRegister::A), MATHTarget::Register(Self::r(r_index)), ), 1 => Instruction::ADC( // ADC A, r[z] MATHTarget::Register(InstrRegister::A), MATHTarget::Register(Self::r(r_index)), ), 2 => Instruction::SUB(MATHTarget::Register(Self::r(r_index))), // SUB r[z] 3 => Instruction::SBC( // SBC A, r[z] MATHTarget::Register(InstrRegister::A), MATHTarget::Register(Self::r(r_index)), ), 4 => Instruction::AND(MATHTarget::Register(Self::r(r_index))), // AND r[z] 5 => Instruction::XOR(MATHTarget::Register(Self::r(r_index))), // XOR r[z] 6 => Instruction::OR(MATHTarget::Register(Self::r(r_index))), // OR r[z] 7 => Instruction::CP(MATHTarget::Register(Self::r(r_index))), // CP r[z] _ => unreachable!("Index {} is out of bounds in alu[]"), } } pub fn x3_alu(fn_index: u8, byte: u8) -> Instruction { unimplemented!() } }