def sbc(cpu, opcode, logger):
logger.info("SBC HL")
regInd = (opcode & 0x30) >> 4
value = 0
if regInd == 0:
value = cpu.BC
elif regInd == 1:
value = cpu.DE
elif regInd == 2:
value = cpu.HL
elif regInd == 3:
value = cpu.SP
oldHL = cpu.HL
logger.info("Old value of HL: " + str(oldHL))
cpu.HL = cpu.HL - value - (1 if cpu.CFlag else 0)
logger.info("New value of HL: " + str(cpu.HL))
cpu.flags[SF] = Bits.signFlag(cpu.HL, bits=16)
cpu.flags[ZF] = Bits.isZero(cpu.HL)
cpu.flags[HF] = Bits.halfCarrySub16(oldHL, cpu.HL)
cpu.flags[PVF] = Bits.overflow(Bits.twos_comp(oldHL, bits=16),
Bits.twos_comp(cpu.HL, bits=16))
cpu.flags[NF] = True
cpu.flags[CF] = Bits.borrow(cpu.HL, bits=16)
def jr_e(cpu, opcode, logger):
pc = cpu.PC
jumpOffset = Bits.twos_comp(cpu.ram[pc])
cpu.PC = pc + jumpOffset + 1
cpu.m_cycles, cpu.t_states = 3, 12
logger.info("JR {0:x}".format(jumpOffset))
def jpnc(cpu, opcode, logger):
jumpOffset = Bits.twos_comp(cpu.rom.readMemory(cpu.PC)) - 2
if cpu.CFlag:
return
cpu.PC = cpu.PC + jumpOffset
logger.info("JP NC {0:x}".format(jumpOffset))
def jpnz(cpu, opcode, logger):
jumpOffset = cpu.rom.readMemory(cpu.PC)
if cpu.ZFlag:
return
cpu.PC = cpu.PC + Bits.twos_comp(jumpOffset)
logger.info("JPNZ {0:x}".format(jumpOffset))
def jrz(cpu, opcode, logger):
jumpOffset = Bits.twos_comp(cpu.rom.readMemory(cpu.PC))
if cpu.ZFlag == False:
return
cpu.PC = cpu.PC + jumpOffset
logger.info("JR Z {0:x}".format(jumpOffset))
def jr_c(cpu, opcode, logger):
pc = cpu.PC + 1
jumpOffset = Bits.twos_comp(cpu.ram[pc]) - 2
no_jump = cpu.CFlag is False
pc = pc + jumpOffset
if not no_jump:
cpu.PC = pc
cpu.m_cycles, cpu.t_states = 1, 5
cpu.m_cycles, cpu.t_states = 2, 7
logger.info("JP C {0:04X}".format(pc))
def djnz(cpu, opcode, logger):
pc = cpu.PC
e = cpu.ram[pc]
cpu.B = cpu.B - 1
pc = pc + Bits.twos_comp(e) + 1
if cpu.B != 0:
cpu.m_cycles, cpu.t_states = 1, 5
cpu.PC = pc
cpu.m_cycles, cpu.t_states = 2, 8
logger.info("DJNZ {:04X}".format(pc))
def inc8(cpu, opcode, logger):
logger.info("INC r")
index = ( opcode >> 3 ) & 7
oldValue = cpu.regs[index]
cpu.regs[index] = (cpu.regs[index] + 1 ) & 0xFF
cpu.NFlag = False
cpu.ZFlag = Bits.isZero(cpu.regs[index])
cpu.HFlag = Bits.halfCarrySub(oldValue, cpu.regs[index])
cpu.PVFlag = True if oldValue == 0x7f else False
cpu.SFlag = Bits.twos_comp(cpu.regs[index]) < 0
def jrz(cpu, opcode, logger):
pc = cpu.PC
jumpTo = pc + Bits.twos_comp(cpu.ram[pc]) + 1
no_jump = cpu.ZFlag is False
if not no_jump:
cpu.PC = jumpTo
cpu.m_cycles, cpu.t_states = 1, 5
cpu.m_cycles, cpu.t_states = 2, 7
logger.info("JR Z, {:04X}".format(jumpTo))
def jpnc(cpu, opcode, logger):
pc = cpu.PC
jumpOffset = Bits.twos_comp(cpu.ram[pc])
no_jump = cpu.CFlag
if not no_jump:
cpu.PC = pc + jumpOffset+1
cpu.m_cycles, cpu.t_states = 1, 5
cpu.m_cycles, cpu.t_states = 2, 7
logger.info("JR NC, {0:04X}".format(pc+jumpOffset+1))
