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feat: Implement prefixed opcode decoding

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This commit is contained in:
Rekai Nyangadzayi Musuka
2020-09-07 21:18:53 -05:00
parent a9510bed54
commit 7538f946d4
1 changed files with 103 additions and 60 deletions
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163
src/instruction.rs
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@@ -35,6 +35,17 @@ pub enum Instruction {
CALL(JumpCondition, u16),
PUSH(RegisterPair),
RST(u8),
RLC(InstrRegister),
RRC(InstrRegister),
RL(InstrRegister),
RR(InstrRegister),
SLA(InstrRegister),
SRA(InstrRegister),
SWAP(InstrRegister),
SRL(InstrRegister),
BIT(u8, InstrRegister),
RES(u8, InstrRegister),
SET(u8, InstrRegister),
}
#[derive(Debug, Copy, Clone)]
@@ -1159,13 +1170,13 @@ impl Instruction {
impl Instruction {
pub fn from_byte(cpu: &Cpu, byte: u8) -> Self {
if byte == 0xCB {
Self::from_prefixed_byte(cpu, byte)
Self::from_prefixed_byte(cpu)
} else {
Self::from_unprefixed_byte(cpu, byte)
}
}
fn from_prefixed_byte(cpu: &Cpu, opcode: u8) -> Self {
fn from_unprefixed_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;
@@ -1177,157 +1188,157 @@ impl Instruction {
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(
(0, 0, _, 0, _) => Self::NOP, // NOP
(0, 0, _, 1, _) => Self::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(
(0, 0, _, 2, _) => Self::STOP, // STOP
(0, 0, _, 3, _) => Self::JR(JumpCondition::Always, n as i8), // JR d
(0, 0, _, 4..=7, _) => Self::JR(Table::cc(y - 4), n as i8), // JR cc[y - 4], d
(0, 1, 0, _, _) => Self::LD(
// LD rp[p], nn
LDTarget::RegisterPair(Table::rp(p)),
LDTarget::ImmediateWord(nn),
),
(0, 1, 1, _, _) => Instruction::ADD(
(0, 1, 1, _, _) => Self::ADD(
// ADD HL, rp[p]
MATHTarget::HL,
MATHTarget::RegisterPair(Table::rp(p)),
),
(0, 2, 0, _, 0) => Instruction::LD(
(0, 2, 0, _, 0) => Self::LD(
// LD (BC), A
LDTarget::IndirectRegister(InstrRegisterPair::BC),
LDTarget::Register(InstrRegister::A),
),
(0, 2, 0, _, 1) => Instruction::LD(
(0, 2, 0, _, 1) => Self::LD(
// LD (DE), A
LDTarget::IndirectRegister(InstrRegisterPair::DE),
LDTarget::Register(InstrRegister::A),
),
(0, 2, 1, _, 0) => Instruction::LD(
(0, 2, 1, _, 0) => Self::LD(
// LD A, (BC)
LDTarget::Register(InstrRegister::A),
LDTarget::IndirectRegister(InstrRegisterPair::BC),
),
(0, 2, 1, _, 1) => Instruction::LD(
(0, 2, 1, _, 1) => Self::LD(
// LD A, (DE)
LDTarget::Register(InstrRegister::A),
LDTarget::IndirectRegister(InstrRegisterPair::DE),
),
(0, 2, 0, _, 2) => Instruction::LD(
(0, 2, 0, _, 2) => Self::LD(
// LD (HL+), A
LDTarget::IndirectRegister(InstrRegisterPair::IncrementHL),
LDTarget::Register(InstrRegister::A),
),
(0, 2, 0, _, 3) => Instruction::LD(
(0, 2, 0, _, 3) => Self::LD(
// LD (HL-), A
LDTarget::IndirectRegister(InstrRegisterPair::DecrementHL),
LDTarget::Register(InstrRegister::A),
),
(0, 2, 1, _, 2) => Instruction::LD(
(0, 2, 1, _, 2) => Self::LD(
// LD A, (HL+)
LDTarget::Register(InstrRegister::A),
LDTarget::IndirectRegister(InstrRegisterPair::IncrementHL),
),
(0, 2, 1, _, 3) => Instruction::LD(
(0, 2, 1, _, 3) => Self::LD(
// LD A, (HL-)
LDTarget::Register(InstrRegister::A),
LDTarget::IndirectRegister(InstrRegisterPair::DecrementHL),
),
(0, 3, 0, _, _) => Instruction::INC(
(0, 3, 0, _, _) => Self::INC(
// INC rp[p]
Registers::Word(Table::rp(p)),
),
(0, 3, 1, _, _) => Instruction::DEC(
(0, 3, 1, _, _) => Self::DEC(
// DEC rp[p]
Registers::Word(Table::rp(p)),
),
(0, 4, _, _, _) => Instruction::INC(
(0, 4, _, _, _) => Self::INC(
// INC r[y]
Registers::Byte(Table::r(y)),
),
(0, 5, _, _, _) => Instruction::DEC(
(0, 5, _, _, _) => Self::DEC(
// DEC r[y]
Registers::Byte(Table::r(y)),
),
(0, 6, _, _, _) => Instruction::LD(
(0, 6, _, _, _) => Self::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(
(0, 7, _, 0, _) => Self::RLCA,
(0, 7, _, 1, _) => Self::RRCA,
(0, 7, _, 2, _) => Self::RLA,
(0, 7, _, 3, _) => Self::RRA,
(0, 7, _, 4, _) => Self::DAA,
(0, 7, _, 5, _) => Self::CPL,
(0, 7, _, 6, _) => Self::SCF,
(0, 7, _, 7, _) => Self::CCF,
(1, 6, _, 6, _) => Self::HALT,
(1, _, _, _, _) => Self::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(
(3, 0, _, 0..=3, _) => Self::RET(Table::cc(y)), // RET cc[y]
(3, 0, _, 4, _) => Self::LD(
// LD (0xFF00 + n), A
LDTarget::ByteAtAddressWithOffset(n),
LDTarget::Register(InstrRegister::A),
),
(3, 0, _, 5, _) => Instruction::ADD(
(3, 0, _, 5, _) => Self::ADD(
// ADD SP, d
MATHTarget::RegisterPair(RegisterPair::SP),
MATHTarget::ImmediateByte(n),
),
(3, 0, _, 6, _) => Instruction::LD(
(3, 0, _, 6, _) => Self::LD(
// LD A, (0xFF00 + n)
LDTarget::Register(InstrRegister::A),
LDTarget::ByteAtAddressWithOffset(n),
),
(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(
(3, 0, _, 7, _) => Self::LDHL(n as i8), // LD HL, SP + d
(3, 1, 0, _, _) => Self::POP(Table::rp2(p)), // POP rp2[p]
(3, 1, 1, _, 0) => Self::RET(JumpCondition::Always), // RET
(3, 1, 1, _, 1) => Self::RETI,
(3, 1, 1, _, 2) => Self::JP(
// JP HL
JumpCondition::Always,
JPTarget::RegisterPair(RegisterPair::HL),
),
(3, 1, 1, _, 3) => Instruction::LD(
(3, 1, 1, _, 3) => Self::LD(
// LD SP, HL
LDTarget::RegisterPair(RegisterPair::SP),
LDTarget::RegisterPair(RegisterPair::HL),
),
(3, 2, _, 0..=3, _) => Instruction::JP(
(3, 2, _, 0..=3, _) => Self::JP(
// JP cc[y], nn
Table::cc(y),
JPTarget::ImmediateWord(nn),
),
(3, 2, _, 4, _) => Instruction::LD(
(3, 2, _, 4, _) => Self::LD(
// LD (0xFF00 + C) ,A
LDTarget::Register(InstrRegister::IndirectC),
LDTarget::Register(InstrRegister::A),
),
(3, 2, _, 5, _) => Instruction::LD(
(3, 2, _, 5, _) => Self::LD(
// LD (nn), A
LDTarget::ByteAtAddress(nn),
LDTarget::Register(InstrRegister::A),
),
(3, 2, _, 6, _) => Instruction::LD(
(3, 2, _, 6, _) => Self::LD(
// LD A, (0xFF00 + C)
LDTarget::Register(InstrRegister::A),
LDTarget::Register(InstrRegister::IndirectC),
),
(3, 2, _, 7, _) => Instruction::LD(
(3, 2, _, 7, _) => Self::LD(
// LD A, (nn)
LDTarget::Register(InstrRegister::A),
LDTarget::ByteAtAddress(nn),
),
(3, 3, _, 0, _) => Instruction::JP(
(3, 3, _, 0, _) => Self::JP(
// JP nn
JumpCondition::Always,
JPTarget::ImmediateWord(nn),
@@ -1337,15 +1348,15 @@ impl Instruction {
// (3, 3, _, 3, _) => unreachable!(), (removed in documentation)
// (3, 3, _, 4, _) => unreachable!(), (removed in documentation)
// (3, 3, _, 5, _) => unreachable!(), (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, 3, _, 6, _) => Self::DI,
(3, 3, _, 7, _) => Self::EI,
(3, 4, _, 0..=3, _) => Self::CALL(Table::cc(y), nn), // CALL cc[y], nn
// (3, 4, _, 4..=7, _) => unreachable!(), (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, 0, _, _) => Self::PUSH(Table::rp2(p)), // PUSH rp2[p]
(3, 5, 1, _, 0) => Self::CALL(JumpCondition::Always, nn), // CALL nn
// (3, 5, 1, _, 1..=3) => unreachable!(), (removed in documentation)
(3, 6, _, _, _) => Table::x3_alu(y, n),
(3, 7, _, _, _) => Instruction::RST(y * 8), // RST y * 8
(3, 7, _, _, _) => Self::RST(y * 8), // RST y * 8
_ => panic!(
"Unknown Opcode: {:#x?}\n x: {}, z: {}, q: {}, y: {}, p: {}",
opcode, x, z, q, y, p
@@ -1353,8 +1364,26 @@ impl Instruction {
}
}
fn from_unprefixed_byte(cpu: &Cpu, byte: u8) -> Self {
unimplemented!()
fn from_prefixed_byte(cpu: &Cpu) -> Self {
let opcode = cpu.read_byte(cpu.register_pair(RegisterPair::PC) + 1);
// 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;
match x {
0 => Table::rot(y, z),
1 => Self::BIT(y, Table::r(z)),
2 => Self::BIT(y, Table::r(z)),
3 => Self::BIT(y, Table::r(z)),
_ => panic!(
"Unknown Prefixed Opcode: 0xCB {:#x?}\n x: {}, z: {}, q: {}, y: {}, p: {}",
opcode, x, z, q, y, p
),
}
}
}
@@ -1545,8 +1574,8 @@ impl Table {
}
}
pub fn x2_alu(fn_index: u8, r_index: u8) -> Instruction {
match fn_index {
pub fn x2_alu(index: u8, r_index: u8) -> Instruction {
match index {
0 => Instruction::ADD(
// ADD A, r[z]
MATHTarget::Register(InstrRegister::A),
@@ -1563,8 +1592,8 @@ impl Table {
}
}
pub fn x3_alu(fn_index: u8, n: u8) -> Instruction {
match fn_index {
pub fn x3_alu(index: u8, n: u8) -> Instruction {
match index {
0 => Instruction::ADD(
// ADD A, n
MATHTarget::Register(InstrRegister::A),
@@ -1580,4 +1609,18 @@ impl Table {
_ => unreachable!("Index {} is out of bounds in alu[]"),
}
}
pub fn rot(index: u8, r_index: u8) -> Instruction {
match index {
0 => Instruction::RLC(Self::r(r_index)),
1 => Instruction::RRC(Self::r(r_index)),
2 => Instruction::RL(Self::r(r_index)),
3 => Instruction::RR(Self::r(r_index)),
4 => Instruction::SLA(Self::r(r_index)),
5 => Instruction::SRA(Self::r(r_index)),
6 => Instruction::SWAP(Self::r(r_index)),
7 => Instruction::SRL(Self::r(r_index)),
_ => unreachable!("Index {} is out of bounds in rot[]"),
}
}
}