def ABX(cpu: CPU6502):
lo, hi = cpu.cpu_read_2(cpu.state.pc)
cpu.state.pc += 2
cpu.state.addr_abs = (hi << 8) | lo
cpu.state.addr_abs += cpu.state.x
if (cpu.state.addr_abs & 0xff00) != (hi << 8):
return 1
else:
return 0
def ABY(cpu: CPU6502):
lo, hi = cpu.cpu_read_2(cpu.state.pc)
cpu.state.pc += 2
addr = ((hi << 8) | lo) + cpu.state.y
cpu.state.addr_abs = addr & 0xFFFF
if (addr & 0xff00) != (hi << 8):
return 1
else:
return 0
def IND(cpu: CPU6502):
ptr_lo, ptr_hi = cpu.cpu_read_2(cpu.state.pc)
cpu.state.pc += 2
ptr = (ptr_hi << 8) | ptr_lo
if ptr_lo == 0x00ff: # Simulate page boundary hardware bug
cpu.state.addr_abs = (
cpu.cpu_read(ptr & 0xff00) << 8) | cpu.cpu_read(ptr + 0)
else:
cpu.state.addr_abs = (cpu.cpu_read(ptr + 1) << 8) | cpu.cpu_read(ptr +
0)
return 0
def ABS(cpu: CPU6502):
lo, hi = cpu.cpu_read_2(cpu.state.pc)
cpu.state.pc += 2
cpu.state.addr_abs = (hi << 8) | lo
return 0