vgbc/cpu/cpu.h

#pragma once

#include "types.h"

class Cpu;
class Mem_device;

enum Flags {
  F_ZERO = 0x8,
  F_SUB = 0x4,
  F_HALF = 0x2,
  F_CARRY = 0x1,
};

union Register_pair {
  struct { u8 hi; u8 lo; }
  u16 hilo;
};

struct Cpu_state {
  // Registers
  union {
    u16 BC;
    struct { u8 B; u8 C; };
  };
  union {
    u16 DE;
    struct { u8 D; u8 E; };
  };
  union {
    u16 HL;
    struct { u8 H; u8 L; };
  };

  u8 A;
  u16 SP;
  u16 PC;

  bool zero;
  bool subtract;
  bool halfcarry;
  bool carry;
};

class Cpu {
private:
  Cpu_state state;
  Mem_device* bus;

  typedef u8 opcode_t;

private:
  u8 readPC();

  void pushStack(u8 data);
  u8 popStack();

public:
  Cpu();

  void step();
};