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#[derive(Copy, Clone)]
pub enum Register {
A,
B,
C,
D,
H,
Z,
}
pub enum RegisterOrImm {
Reg(Register),
Imm8(u8),
}
pub struct Assembler {
buffer: Vec<u8>,
}
impl Assembler {
pub fn new() -> Assembler {
Assembler { buffer: Vec::new() }
}
pub fn bytes(&self) -> Vec<u8> {
self.buffer.clone()
}
/// Moves a register or 8-bit immediate value from `src` into a register `dest`.
pub fn mw(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(dest as u8);
self.buffer.push(value);
}
}
}
/// Loads a 8-bit value from memory into a register `dest`.
/// If `src` is `Some(...)`, the value passed in `src` is used as the source address.
/// If `src` is `None`, the value in the `HL` register is used as the source address.
pub fn lw(&mut self, dest: Register, src: Option<u16>) {
match src {
Some(addr) => {
self.buffer.push(0x01 << 4 | dest as u8);
self.emit_u16(addr);
}
None => {
self.buffer.push(0x01 << 4 | 0x08 | dest as u8);
}
}
}
/// Stores an 8-bit value from a register `src` into memory.
/// If `dest` is `Some(...)`, the value passed in `dest` is used as the destination address.
/// If `dest` is `None`, the value in the `HL` register is used as the destination address.
pub fn sw(&mut self, dest: Option<u16>, src: Register) {
match dest {
Some(addr) => {
self.buffer.push(0x02 << 4 | src as u8);
self.emit_u16(addr);
}
None => {
self.buffer.push(0x02 << 4 | 0x08 | src as u8);
}
}
}
/// Pushes a register or 8-bit immediate value onto the stack.
pub fn push(&mut self, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x03 << 4 | 0x08 | reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x03 << 4);
self.buffer.push(value);
}
}
}
/// Pops a value from the stack and loads it into a register `dest`.
pub fn pop(&mut self, dest: Register) {
self.buffer.push(0x04 << 4 | 0x08 | dest as u8);
}
/// Loads a 16-bit value from memory into the `HL` register.
pub fn lda(&mut self, addr: u16) {
self.buffer.push(5 << 4);
self.emit_u16(addr);
}
/// Jumps to the address specified by the `HL` register if the immediate value `src` or the
/// value in the register `src` is not zero.
pub fn jnz(&mut self, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x06 << 4 | 0x08 | reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x06 << 4);
self.buffer.push(value);
}
}
}
/// Reads a byte from the port specified by `src` into a register `dest`.
pub fn inb(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x07 << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x07 << 4 | dest as u8);
self.buffer.push(value);
}
}
}
/// Writes a byte from a register `src` to the port specified by `dest`.
pub fn outb(&mut self, dest: RegisterOrImm, src: Register) {
match dest {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x08 << 4 | 0x08 | src as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x08 << 4 | src as u8);
self.buffer.push(value);
}
}
}
/// Adds a register or 8-bit immediate value `src` and the value in a register `dest`.
/// The result is stored in the register `dest`.
pub fn add(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x09 << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x09 << 4 | dest as u8);
self.buffer.push(value);
}
}
}
/// Adds with carry a register or 8-bit immediate value `src` and the value in a register `dest`.
/// The result is stored in the register `dest`.
pub fn adc(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x0A << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x0A << 4 | dest as u8);
self.buffer.push(value);
}
}
}
/// Performs a bitwise AND operating on a register or 8-bit immediate value `src` and the value in a register `dest`.
/// The result is stored in the register `dest`.
pub fn and(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x0B << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x0B << 4 | dest as u8);
self.buffer.push(value);
}
}
}
/// Performs a bitwise OR operating on a register or 8-bit immediate value `src` and the value in a register `dest`.
/// The result is stored in the register `dest`.
pub fn or(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x0C << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x0C << 4 | dest as u8);
self.buffer.push(value);
}
}
}
/// Performs a bitwise NOR operating on a register or 8-bit immediate value `src` and the value in a register `dest`.
/// The result is stored in the register `dest`.
///
/// # Panics
///
/// Panics if the `src` operand is not `RegisterOrImm::Reg()` or `RegisterOrImm:Imm8()`.
pub fn nor(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x0D << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x0D << 4 | dest as u8);
self.buffer.push(value);
}
}
}
/// Compares a register or 8-bit immediate value `src` and the value in a register `dest`.
/// Sets the flags register accordingly.
///
/// # Panics
///
/// Panics if the `src` operand is not `RegisterOrImm::Reg()` or `RegisterOrImm:Imm8()`.
pub fn cmp(&mut self, left: Register, right: RegisterOrImm) {
match right {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x0E << 4 | 0x08 | left as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x0E << 4 | left as u8);
self.buffer.push(value);
}
}
}
/// Subtracts a register or 8-bit immediate value `src` from the value in a register `dest`.
/// The result is stored in the register `dest`.
///
/// # Panics
///
/// Panics if the `src` operand is not `RegisterOrImm::Reg()` or `RegisterOrImm:Imm8()`.
pub fn sbb(&mut self, dest: Register, src: RegisterOrImm) {
match src {
RegisterOrImm::Reg(reg) => {
self.buffer.push(0x0F << 4 | 0x08 | dest as u8);
self.buffer.push(reg as u8);
}
RegisterOrImm::Imm8(value) => {
self.buffer.push(0x0F << 4 | dest as u8);
self.buffer.push(value);
}
}
}
#[inline(always)]
fn emit_u16(&mut self, value: u16) {
self.buffer.push((value & 0xFF) as u8);
self.buffer.push((value >> 8) as u8);
}
}