package core6502 import "fmt" const ( regA = 0 regX = 1 regY = 2 regP = 4 regSP = 5 regPC = 6 // 2 bytes regNone = -1 ) const ( flagN uint8 = 1 << 7 flagV uint8 = 1 << 6 flag5 uint8 = 1 << 5 flagB uint8 = 1 << 4 flagD uint8 = 1 << 3 flagI uint8 = 1 << 2 flagZ uint8 = 1 << 1 flagC uint8 = 1 << 0 ) type registers struct { data [8]uint8 } func (r *registers) getRegister(i int) uint8 { return r.data[i] } func (r *registers) getA() uint8 { return r.data[regA] } func (r *registers) getX() uint8 { return r.data[regX] } func (r *registers) getY() uint8 { return r.data[regY] } func (r *registers) getP() uint8 { return r.data[regP] } func (r *registers) getSP() uint8 { return r.data[regSP] } func (r *registers) setRegister(i int, v uint8) { r.data[i] = v } func (r *registers) setA(v uint8) { r.setRegister(regA, v) } func (r *registers) setX(v uint8) { r.setRegister(regX, v) } func (r *registers) setY(v uint8) { r.setRegister(regY, v) } func (r *registers) setP(v uint8) { r.setRegister(regP, v) } func (r *registers) setSP(v uint8) { r.setRegister(regSP, v) } func (r *registers) getPC() uint16 { return uint16(r.data[regPC])*256 + uint16(r.data[regPC+1]) } func (r *registers) setPC(v uint16) { r.data[regPC] = uint8(v >> 8) r.data[regPC+1] = uint8(v) } func (r *registers) getFlagBit(i uint8) uint8 { if r.getFlag(i) { return 1 } return 0 } func (r *registers) getFlag(i uint8) bool { return (r.data[regP] & i) != 0 } func (r *registers) setFlag(i uint8) { r.data[regP] |= i } func (r *registers) clearFlag(i uint8) { r.data[regP] &^= i } func (r *registers) updateFlag(i uint8, v bool) { if v { r.setFlag(i) } else { r.clearFlag(i) } } func (r *registers) updateFlagZN(t uint8) { r.updateFlag(flagZ, t == 0) r.updateFlag(flagN, t >= (1<<7)) } func (r registers) String() string { return fmt.Sprintf("A: %#02x, X: %#02x, Y: %#02x, SP: %#02x, PC: %#04x, P: %#02x, (NV-BDIZC): %08b", r.getA(), r.getX(), r.getY(), r.getSP(), r.getPC(), r.getP(), r.getP()) }