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pub const INSTRUCTIONS: [(fn(&mut Cpu), u8, &'static str); 176] = [
// 0x0 opcodes
(nop, 4, "NOP"),
(ld_bc_u16, 12, "LD BC, NN"),
(ld_mbc_a, 8, "LD [BC], A"),
(inc_bc, 8, "INC BC"),
(inc_b, 4, "INC B"),
(dec_b, 4, "DEC B"),
(ld_b_u8, 8, "LD B, N"),
(rlca, 4, "RLCA"),
(ld_mu16_sp, 20, "LD [u16], SP"),
(add_hl_bc, 8, "ADD HL, BC"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x1 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x3 opcodes
(nop, 4, "NOP"),
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(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x4 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x5 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x6 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x7 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x8 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0x9 opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
// 0xa opcodes
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(nop, 4, "NOP"),
(xor_a_a, 4, "XOR A, A"),
a: u8,
b: u8,
c: u8,
d: u8,
e: u8,
h: u8,
l: u8,
zero: bool,
sub: bool,
half_carry: bool,
carry: bool,
a: 0x0,
b: 0x0,
c: 0x0,
d: 0x0,
e: 0x0,
h: 0x0,
l: 0x0,
zero: false,
sub: false,
half_carry: false,
carry: false,
}
}
pub fn clock(&mut self) {
// fetches the current instruction and increments
// the PC (program counter) accordingly
let opcode = self.mmu.read(self.pc);
let instruction = INSTRUCTIONS[opcode as usize];
let (instruction_fn, instruction_size, instruction_str) = instruction;
instruction_fn(self);
self.clocks = self.clocks.wrapping_add(instruction_size as u32);
println!("{} ({:#x})", instruction_str, opcode)
#[inline(always)]
pub fn mmu(&mut self) -> &mut Mmu {
&mut self.mmu
}
fn af(&self) -> u16 {
(self.a as u16) << 8 | self.f() as u16
fn bc(&self) -> u16 {
(self.b as u16) << 8 | self.c as u16
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fn f(&self) -> u8 {
let mut f = 0x0u8;
if self.zero {
f |= 0x80;
}
if self.sub {
f |= 0x40;
}
if self.half_carry {
f |= 0x20;
}
if self.carry {
f |= 0x10;
}
f
}
#[inline(always)]
fn set_bc(&mut self, value: u16) {
self.b = (value >> 8) as u8;
self.c = value as u8;
}
#[inline(always)]
fn de(&self) -> u16 {
(self.d as u16) << 8 | self.e as u16
}
#[inline(always)]
fn set_de(&mut self, value: u16) {
self.d = (value >> 8) as u8;
self.e = value as u8;
fn hl(&self) -> u16 {
(self.h as u16) << 8 | self.l as u16
}
#[inline(always)]
fn set_hl(&mut self, value: u16) {
self.h = (value >> 8) as u8;
self.l = value as u8;
byte
}
#[inline(always)]
fn read_u16(&mut self) -> u16 {
let byte1 = self.read_u8();
let byte2 = self.read_u8();
let word = byte1 as u16 | ((byte2 as u16) << 8);
word
}
#[inline(always)]
fn get_zero(&self) -> bool {
self.zero
}
#[inline(always)]
fn set_zero(&mut self, value: bool) {
self.zero = value
self.sub
}
#[inline(always)]
fn set_sub(&mut self, value: bool) {
self.sub = value;
self.half_carry
}
#[inline(always)]
fn set_half_carry(&mut self, value: bool) {
self.half_carry = value
self.carry
}
#[inline(always)]
fn set_carry(&mut self, value: bool) {
self.carry = value;
fn nop(_cpu: &mut Cpu) {}
fn ld_bc_u16(cpu: &mut Cpu) {
let word = cpu.read_u16();
cpu.set_bc(word);
}
fn ld_mbc_a(cpu: &mut Cpu) {
}
fn inc_bc(cpu: &mut Cpu) {
cpu.set_bc(cpu.bc().wrapping_add(1));
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fn inc_b(cpu: &mut Cpu) {
let value = cpu.b.wrapping_add(1);
cpu.set_sub(false);
cpu.set_zero(value == 0);
cpu.set_half_carry((value & 0xf) == 0xf);
cpu.b = value;
}
fn dec_b(cpu: &mut Cpu) {
let value = cpu.b.wrapping_sub(1);
cpu.set_sub(true);
cpu.set_zero(value == 0);
cpu.set_half_carry((value & 0xf) == 0xf);
cpu.b = value;
}
fn ld_b_u8(cpu: &mut Cpu) {
let byte = cpu.read_u8();
cpu.b = byte;
}
fn rlca(cpu: &mut Cpu) {
let carry = cpu.a >> 7;
cpu.a = cpu.a << 1 | carry;
cpu.set_sub(false);
cpu.set_zero(false);
cpu.set_half_carry(false);
cpu.set_carry(carry == 1);
}
fn ld_mu16_sp(cpu: &mut Cpu) {
let word = cpu.read_u16();
cpu.mmu.write(word, cpu.sp as u8);
cpu.mmu.write(word + 1, (cpu.sp >> 8) as u8);
let value = add_u16_u16(cpu, cpu.hl(), cpu.bc());
cpu.set_hl(value);
}
fn ld_sp_u16(cpu: &mut Cpu) {
cpu.sp = cpu.read_u16();
}
fn xor_a_a(cpu: &mut Cpu) {
cpu.a ^= cpu.a
}
fn add_u16_u16(cpu: &mut Cpu, first: u16, second: u16) -> u16 {
let first = first as u32;
let second = second as u32;
let value = first.wrapping_add(second);
cpu.set_sub(false);
cpu.set_carry(value & 0x1000 == 0x1000);
cpu.set_half_carry((first ^ second ^ value) & 0x1000 == 0x1000);
value as u16
}