Apple-2-Tools/applepy
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15e174c02a
applepy/cpu6502.py
Greg Hewgill 15e174c02a rename --ui switch to --bus
2011-08-19 20:30:55 +12:00

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# ApplePy - an Apple ][ emulator in Python
# James Tauber / http://jtauber.com/
# originally written 2001, updated 2011
import socket
import struct
import sys
bus = None # socket for bus I/O
def signed(x):
if x > 0x7F:
x = x - 0x100
return x
class ROM:
def __init__(self, start, size):
self.start = start
self.end = start + size - 1
self._mem = [0x00] * size
def load(self, address, data):
for offset, datum in enumerate(data):
self._mem[address - self.start + offset] = datum
def load_file(self, address, filename):
with open(filename) as f:
for offset, datum in enumerate(f.read()):
self._mem[address - self.start + offset] = ord(datum)
def read_byte(self, address):
assert self.start <= address <= self.end
return self._mem[address - self.start]
class RAM(ROM):
def write_byte(self, address, value):
self._mem[address] = value
class Memory:
def __init__(self, options=None, use_bus=True):
self.use_bus = use_bus
self.rom = ROM(0xD000, 0x3000)
if options:
self.rom.load_file(0xD000, options.rom)
self.ram = RAM(0x0000, 0xC000)
if options and options.ram:
self.ram.load_file(0x0000, options.ram)
def load(self, address, data):
if address < 0xC000:
self.ram.load(address, data)
def read_byte(self, cycle, address):
if address < 0xC000:
return self.ram.read_byte(address)
elif address < 0xD000:
return self.bus_read(cycle, address)
else:
return self.rom.read_byte(address)
def read_word(self, cycle, address):
return self.read_byte(cycle, address) + (self.read_byte(cycle + 1, address + 1) << 8)
def read_word_bug(self, cycle, address):
if address % 0x100 == 0xFF:
return self.read_byte(cycle, address) + (self.read_byte(cycle + 1, address & 0xFF00) << 8)
else:
return self.read_word(cycle, address)
def write_byte(self, cycle, address, value):
if address < 0xC000:
self.ram.write_byte(address, value)
if 0x400 <= address < 0x800 or 0x2000 <= address < 0x5FFF:
self.bus_write(cycle, address, value)
def bus_read(self, cycle, address):
if not self.use_bus:
return 0
op = struct.pack("<IBHB", cycle, 0, address, 0)
try:
bus.send(op)
b = bus.recv(1)
if len(b) == 0:
sys.exit(0)
return ord(b)
except socket.error:
sys.exit(0)
def bus_write(self, cycle, address, value):
if not self.use_bus:
return
op = struct.pack("<IBHB", cycle, 1, address, value)
try:
bus.send(op)
except IOError:
sys.exit(0)
class Disassemble:
def __init__(self, cpu, memory):
self.cpu = cpu
self.memory = memory
self.setup_ops()
def setup_ops(self):
self.ops = [None] * 0x100
self.ops[0x00] = ("BRK", )
self.ops[0x01] = ("ORA", self.indirect_x_mode)
self.ops[0x05] = ("ORA", self.zero_page_mode)
self.ops[0x06] = ("ASL", self.zero_page_mode)
self.ops[0x08] = ("PHP", )
self.ops[0x09] = ("ORA", self.immediate_mode)
self.ops[0x0A] = ("ASL", )
self.ops[0x0D] = ("ORA", self.absolute_mode)
self.ops[0x0E] = ("ASL", self.absolute_mode)
self.ops[0x10] = ("BPL", self.relative_mode)
self.ops[0x11] = ("ORA", self.indirect_y_mode)
self.ops[0x15] = ("ORA", self.zero_page_x_mode)
self.ops[0x16] = ("ASL", self.zero_page_x_mode)
self.ops[0x18] = ("CLC", )
self.ops[0x19] = ("ORA", self.absolute_y_mode)
self.ops[0x1D] = ("ORA", self.absolute_x_mode)
self.ops[0x1E] = ("ASL", self.absolute_x_mode)
self.ops[0x20] = ("JSR", self.absolute_mode)
self.ops[0x21] = ("AND", self.indirect_x_mode)
self.ops[0x24] = ("BIT", self.zero_page_mode)
self.ops[0x25] = ("AND", self.zero_page_mode)
self.ops[0x26] = ("ROL", self.zero_page_mode)
self.ops[0x28] = ("PLP", )
self.ops[0x29] = ("AND", self.immediate_mode)
self.ops[0x2A] = ("ROL", )
self.ops[0x2C] = ("BIT", self.absolute_mode)
self.ops[0x2D] = ("AND", self.absolute_mode)
self.ops[0x2E] = ("ROL", self.absolute_mode)
self.ops[0x30] = ("BMI", self.relative_mode)
self.ops[0x31] = ("AND", self.indirect_y_mode)
self.ops[0x35] = ("AND", self.zero_page_x_mode)
self.ops[0x36] = ("ROL", self.zero_page_x_mode)
self.ops[0x38] = ("SEC", )
self.ops[0x39] = ("AND", self.absolute_y_mode)
self.ops[0x3D] = ("AND", self.absolute_x_mode)
self.ops[0x3E] = ("ROL", self.absolute_x_mode)
self.ops[0x40] = ("RTI", )
self.ops[0x41] = ("EOR", self.indirect_x_mode)
self.ops[0x45] = ("EOR", self.zero_page_mode)
self.ops[0x46] = ("LSR", self.zero_page_mode)
self.ops[0x48] = ("PHA", )
self.ops[0x49] = ("EOR", self.immediate_mode)
self.ops[0x4A] = ("LSR", )
self.ops[0x4C] = ("JMP", self.absolute_mode)
self.ops[0x4D] = ("EOR", self.absolute_mode)
self.ops[0x4E] = ("LSR", self.absolute_mode)
self.ops[0x50] = ("BVC", self.relative_mode)
self.ops[0x51] = ("EOR", self.indirect_y_mode)
self.ops[0x55] = ("EOR", self.zero_page_x_mode)
self.ops[0x56] = ("LSR", self.zero_page_x_mode)
self.ops[0x58] = ("CLI", )
self.ops[0x59] = ("EOR", self.absolute_y_mode)
self.ops[0x5D] = ("EOR", self.absolute_x_mode)
self.ops[0x5E] = ("LSR", self.absolute_x_mode)
self.ops[0x60] = ("RTS", )
self.ops[0x61] = ("ADC", self.indirect_x_mode)
self.ops[0x65] = ("ADC", self.zero_page_mode)
self.ops[0x66] = ("ROR", self.zero_page_mode)
self.ops[0x68] = ("PLA", )
self.ops[0x69] = ("ADC", self.immediate_mode)
self.ops[0x6A] = ("ROR", )
self.ops[0x6C] = ("JMP", self.indirect_mode)
self.ops[0x6D] = ("ADC", self.absolute_mode)
self.ops[0x6E] = ("ROR", self.absolute_mode)
self.ops[0x70] = ("BVS", self.relative_mode)
self.ops[0x71] = ("ADC", self.indirect_y_mode)
self.ops[0x75] = ("ADC", self.zero_page_x_mode)
self.ops[0x76] = ("ROR", self.zero_page_x_mode)
self.ops[0x78] = ("SEI", )
self.ops[0x79] = ("ADC", self.absolute_y_mode)
self.ops[0x7D] = ("ADC", self.absolute_x_mode)
self.ops[0x7E] = ("ROR", self.absolute_x_mode)
self.ops[0x81] = ("STA", self.indirect_x_mode)
self.ops[0x84] = ("STY", self.zero_page_mode)
self.ops[0x85] = ("STA", self.zero_page_mode)
self.ops[0x86] = ("STX", self.zero_page_mode)
self.ops[0x88] = ("DEY", )
self.ops[0x8A] = ("TXA", )
self.ops[0x8C] = ("STY", self.absolute_mode)
self.ops[0x8D] = ("STA", self.absolute_mode)
self.ops[0x8E] = ("STX", self.absolute_mode)
self.ops[0x90] = ("BCC", self.relative_mode)
self.ops[0x91] = ("STA", self.indirect_y_mode)
self.ops[0x94] = ("STY", self.zero_page_x_mode)
self.ops[0x95] = ("STA", self.zero_page_x_mode)
self.ops[0x96] = ("STX", self.zero_page_y_mode)
self.ops[0x98] = ("TYA", )
self.ops[0x99] = ("STA", self.absolute_y_mode)
self.ops[0x9A] = ("TXS", )
self.ops[0x9D] = ("STA", self.absolute_x_mode)
self.ops[0xA0] = ("LDY", self.immediate_mode)
self.ops[0xA1] = ("LDA", self.indirect_x_mode)
self.ops[0xA2] = ("LDX", self.immediate_mode)
self.ops[0xA4] = ("LDY", self.zero_page_mode)
self.ops[0xA5] = ("LDA", self.zero_page_mode)
self.ops[0xA6] = ("LDX", self.zero_page_mode)
self.ops[0xA8] = ("TAY", )
self.ops[0xA9] = ("LDA", self.immediate_mode)
self.ops[0xAA] = ("TAX", )
self.ops[0xAC] = ("LDY", self.absolute_mode)
self.ops[0xAD] = ("LDA", self.absolute_mode)
self.ops[0xAE] = ("LDX", self.absolute_mode)
self.ops[0xB0] = ("BCS", self.relative_mode)
self.ops[0xB1] = ("LDA", self.indirect_y_mode)
self.ops[0xB4] = ("LDY", self.zero_page_x_mode)
self.ops[0xB5] = ("LDA", self.zero_page_x_mode)
self.ops[0xB6] = ("LDX", self.zero_page_y_mode)
self.ops[0xB8] = ("CLV", )
self.ops[0xB9] = ("LDA", self.absolute_y_mode)
self.ops[0xBA] = ("TSX", )
self.ops[0xBC] = ("LDY", self.absolute_x_mode)
self.ops[0xBD] = ("LDA", self.absolute_x_mode)
self.ops[0xBE] = ("LDX", self.absolute_y_mode)
self.ops[0xC0] = ("CPY", self.immediate_mode)
self.ops[0xC1] = ("CMP", self.indirect_x_mode)
self.ops[0xC4] = ("CPY", self.zero_page_mode)
self.ops[0xC5] = ("CMP", self.zero_page_mode)
self.ops[0xC6] = ("DEC", self.zero_page_mode)
self.ops[0xC8] = ("INY", )
self.ops[0xC9] = ("CMP", self.immediate_mode)
self.ops[0xCA] = ("DEX", )
self.ops[0xCC] = ("CPY", self.absolute_mode)
self.ops[0xCD] = ("CMP", self.absolute_mode)
self.ops[0xCE] = ("DEC", self.absolute_mode)
self.ops[0xD0] = ("BNE", self.relative_mode)
self.ops[0xD1] = ("CMP", self.indirect_y_mode)
self.ops[0xD5] = ("CMP", self.zero_page_x_mode)
self.ops[0xD6] = ("DEC", self.zero_page_x_mode)
self.ops[0xD8] = ("CLD", )
self.ops[0xD9] = ("CMP", self.absolute_y_mode)
self.ops[0xDD] = ("CMP", self.absolute_x_mode)
self.ops[0xDE] = ("DEC", self.absolute_x_mode)
self.ops[0xE0] = ("CPX", self.immediate_mode)
self.ops[0xE1] = ("SBC", self.indirect_x_mode)
self.ops[0xE4] = ("CPX", self.zero_page_mode)
self.ops[0xE5] = ("SBC", self.zero_page_mode)
self.ops[0xE6] = ("INC", self.zero_page_mode)
self.ops[0xE8] = ("INX", )
self.ops[0xE9] = ("SBC", self.immediate_mode)
self.ops[0xEA] = ("NOP", )
self.ops[0xEC] = ("CPX", self.absolute_mode)
self.ops[0xED] = ("SBC", self.absolute_mode)
self.ops[0xEE] = ("INC", self.absolute_mode)
self.ops[0xF0] = ("BEQ", self.relative_mode)
self.ops[0xF1] = ("SBC", self.indirect_y_mode)
self.ops[0xF5] = ("SBC", self.zero_page_x_mode)
self.ops[0xF6] = ("INC", self.zero_page_x_mode)
self.ops[0xF8] = ("SED", )
self.ops[0xF9] = ("SBC", self.absolute_y_mode)
self.ops[0xFD] = ("SBC", self.absolute_x_mode)
self.ops[0xFE] = ("INC", self.absolute_x_mode)
def absolute_mode(self, pc):
a = self.memory.read_word(pc + 1)
return "$%04X [%04X] = %02X" % (a, a, self.memory.read_word(a))
def absolute_x_mode(self, pc):
a = self.memory.read_word(pc + 1)
e = a + self.cpu.x_index
return "$%04X,X [%04X] = %02X" % (a, e, self.memory.read_byte(e))
def absolute_y_mode(self, pc):
a = self.memory.read_word(pc + 1)
e = a + self.cpu.y_index
return "$%04X,Y [%04X] = %02X" % (a, e, self.memory.read_byte(e))
def immediate_mode(self, pc):
return "#$%02X" % (self.memory.read_byte(pc + 1))
def indirect_mode(self, pc):
a = self.memory.read_word(pc + 1)
return "($%04X) [%04X] = %02X" % (a, a, self.memory.read_word(a))
def indirect_x_mode(self, pc):
z = self.memory.read_byte(pc + 1)
a = self.memory.read_word((z + self.cpu.x_index) % 0x100)
return "($%02X,X) [%04X] = %02X" % (z, a, self.memory.read_byte(a))
def indirect_y_mode(self, pc):
z = self.memory.read_byte(pc + 1)
a = self.memory.read_word(z) + self.cpu.y_index
return "($%02X),Y [%04X] = %02X" % (z, a, self.memory.read_byte(a))
def relative_mode(self, pc):
return "$%04X" % (pc + signed(self.memory.read_byte(pc + 1) + 2))
def zero_page_mode(self, pc):
a = self.memory.read_byte(pc + 1)
return "$%02X [%04X] = %02X" % (a, a, self.memory.read_byte(a))
def zero_page_x_mode(self, pc):
z = self.memory.read_byte(pc + 1)
a = (z + self.cpu.x_index) % 0x100
return "$%02X,X [%04X] = %02X" % (z, a, self.memory.read_byte(a))
def zero_page_y_mode(self, pc):
z = self.memory.read_byte(pc + 1)
a = (z + self.cpu.y_index) % 0x100
return "$%02X,Y [%04X] = %02X" % (z, a, self.memory.read_byte(a))
def disasm(self, pc):
op = self.memory.read_byte(pc)
info = self.ops[op]
s = "%02X %s" % (pc, info[0])
if len(info) > 1:
s += " " + info[1](pc)
return s
class CPU:
STACK_PAGE = 0x100
RESET_VECTOR = 0xFFFC
def __init__(self, memory):
self.memory = memory
self.disassemble = Disassemble(self, memory)
self.accumulator = 0x00
self.x_index = 0x00
self.y_index = 0x00
self.carry_flag = 0
self.zero_flag = 0
self.interrupt_disable_flag = 0
self.decimal_mode_flag = 0
self.break_flag = 1
self.overflow_flag = 0
self.sign_flag = 0
self.stack_pointer = 0xFF
self.cycles = 0
self.setup_ops()
self.reset()
def setup_ops(self):
self.ops = [None] * 0x100
self.ops[0x00] = lambda: self.BRK()
self.ops[0x01] = lambda: self.ORA(self.indirect_x_mode())
self.ops[0x05] = lambda: self.ORA(self.zero_page_mode())
self.ops[0x06] = lambda: self.ASL(self.zero_page_mode())
self.ops[0x08] = lambda: self.PHP()
self.ops[0x09] = lambda: self.ORA(self.immediate_mode())
self.ops[0x0A] = lambda: self.ASL()
self.ops[0x0D] = lambda: self.ORA(self.absolute_mode())
self.ops[0x0E] = lambda: self.ASL(self.absolute_mode())
self.ops[0x10] = lambda: self.BPL(self.relative_mode())
self.ops[0x11] = lambda: self.ORA(self.indirect_y_mode())
self.ops[0x15] = lambda: self.ORA(self.zero_page_x_mode())
self.ops[0x16] = lambda: self.ASL(self.zero_page_x_mode())
self.ops[0x18] = lambda: self.CLC()
self.ops[0x19] = lambda: self.ORA(self.absolute_y_mode())
self.ops[0x1D] = lambda: self.ORA(self.absolute_x_mode())
self.ops[0x1E] = lambda: self.ASL(self.absolute_x_mode(rmw=True))
self.ops[0x20] = lambda: self.JSR(self.absolute_mode())
self.ops[0x21] = lambda: self.AND(self.indirect_x_mode())
self.ops[0x24] = lambda: self.BIT(self.zero_page_mode())
self.ops[0x25] = lambda: self.AND(self.zero_page_mode())
self.ops[0x26] = lambda: self.ROL(self.zero_page_mode())
self.ops[0x28] = lambda: self.PLP()
self.ops[0x29] = lambda: self.AND(self.immediate_mode())
self.ops[0x2A] = lambda: self.ROL()
self.ops[0x2C] = lambda: self.BIT(self.absolute_mode())
self.ops[0x2D] = lambda: self.AND(self.absolute_mode())
self.ops[0x2E] = lambda: self.ROL(self.absolute_mode())
self.ops[0x30] = lambda: self.BMI(self.relative_mode())
self.ops[0x31] = lambda: self.AND(self.indirect_y_mode())
self.ops[0x35] = lambda: self.AND(self.zero_page_x_mode())
self.ops[0x36] = lambda: self.ROL(self.zero_page_x_mode())
self.ops[0x38] = lambda: self.SEC()
self.ops[0x39] = lambda: self.AND(self.absolute_y_mode())
self.ops[0x3D] = lambda: self.AND(self.absolute_x_mode())
self.ops[0x3E] = lambda: self.ROL(self.absolute_x_mode(rmw=True))
self.ops[0x40] = lambda: self.RTI()
self.ops[0x41] = lambda: self.EOR(self.indirect_x_mode())
self.ops[0x45] = lambda: self.EOR(self.zero_page_mode())
self.ops[0x46] = lambda: self.LSR(self.zero_page_mode())
self.ops[0x48] = lambda: self.PHA()
self.ops[0x49] = lambda: self.EOR(self.immediate_mode())
self.ops[0x4A] = lambda: self.LSR()
self.ops[0x4C] = lambda: self.JMP(self.absolute_mode())
self.ops[0x4D] = lambda: self.EOR(self.absolute_mode())
self.ops[0x4E] = lambda: self.LSR(self.absolute_mode())
self.ops[0x50] = lambda: self.BVC(self.relative_mode())
self.ops[0x51] = lambda: self.EOR(self.indirect_y_mode())
self.ops[0x55] = lambda: self.EOR(self.zero_page_x_mode())
self.ops[0x56] = lambda: self.LSR(self.zero_page_x_mode())
self.ops[0x58] = lambda: self.CLI()
self.ops[0x59] = lambda: self.EOR(self.absolute_y_mode())
self.ops[0x5D] = lambda: self.EOR(self.absolute_x_mode())
self.ops[0x5E] = lambda: self.LSR(self.absolute_x_mode(rmw=True))
self.ops[0x60] = lambda: self.RTS()
self.ops[0x61] = lambda: self.ADC(self.indirect_x_mode())
self.ops[0x65] = lambda: self.ADC(self.zero_page_mode())
self.ops[0x66] = lambda: self.ROR(self.zero_page_mode())
self.ops[0x68] = lambda: self.PLA()
self.ops[0x69] = lambda: self.ADC(self.immediate_mode())
self.ops[0x6A] = lambda: self.ROR()
self.ops[0x6C] = lambda: self.JMP(self.indirect_mode())
self.ops[0x6D] = lambda: self.ADC(self.absolute_mode())
self.ops[0x6E] = lambda: self.ROR(self.absolute_mode())
self.ops[0x70] = lambda: self.BVS(self.relative_mode())
self.ops[0x71] = lambda: self.ADC(self.indirect_y_mode())
self.ops[0x75] = lambda: self.ADC(self.zero_page_x_mode())
self.ops[0x76] = lambda: self.ROR(self.zero_page_x_mode())
self.ops[0x78] = lambda: self.SEI()
self.ops[0x79] = lambda: self.ADC(self.absolute_y_mode())
self.ops[0x7D] = lambda: self.ADC(self.absolute_x_mode())
self.ops[0x7E] = lambda: self.ROR(self.absolute_x_mode(rmw=True))
self.ops[0x81] = lambda: self.STA(self.indirect_x_mode())
self.ops[0x84] = lambda: self.STY(self.zero_page_mode())
self.ops[0x85] = lambda: self.STA(self.zero_page_mode())
self.ops[0x86] = lambda: self.STX(self.zero_page_mode())
self.ops[0x88] = lambda: self.DEY()
self.ops[0x8A] = lambda: self.TXA()
self.ops[0x8C] = lambda: self.STY(self.absolute_mode())
self.ops[0x8D] = lambda: self.STA(self.absolute_mode())
self.ops[0x8E] = lambda: self.STX(self.absolute_mode())
self.ops[0x90] = lambda: self.BCC(self.relative_mode())
self.ops[0x91] = lambda: self.STA(self.indirect_y_mode(rmw=True))
self.ops[0x94] = lambda: self.STY(self.zero_page_x_mode())
self.ops[0x95] = lambda: self.STA(self.zero_page_x_mode())
self.ops[0x96] = lambda: self.STX(self.zero_page_y_mode())
self.ops[0x98] = lambda: self.TYA()
self.ops[0x99] = lambda: self.STA(self.absolute_y_mode(rmw=True))
self.ops[0x9A] = lambda: self.TXS()
self.ops[0x9D] = lambda: self.STA(self.absolute_x_mode(rmw=True))
self.ops[0xA0] = lambda: self.LDY(self.immediate_mode())
self.ops[0xA1] = lambda: self.LDA(self.indirect_x_mode())
self.ops[0xA2] = lambda: self.LDX(self.immediate_mode())
self.ops[0xA4] = lambda: self.LDY(self.zero_page_mode())
self.ops[0xA5] = lambda: self.LDA(self.zero_page_mode())
self.ops[0xA6] = lambda: self.LDX(self.zero_page_mode())
self.ops[0xA8] = lambda: self.TAY()
self.ops[0xA9] = lambda: self.LDA(self.immediate_mode())
self.ops[0xAA] = lambda: self.TAX()
self.ops[0xAC] = lambda: self.LDY(self.absolute_mode())
self.ops[0xAD] = lambda: self.LDA(self.absolute_mode())
self.ops[0xAE] = lambda: self.LDX(self.absolute_mode())
self.ops[0xB0] = lambda: self.BCS(self.relative_mode())
self.ops[0xB1] = lambda: self.LDA(self.indirect_y_mode())
self.ops[0xB4] = lambda: self.LDY(self.zero_page_x_mode())
self.ops[0xB5] = lambda: self.LDA(self.zero_page_x_mode())
self.ops[0xB6] = lambda: self.LDX(self.zero_page_y_mode())
self.ops[0xB8] = lambda: self.CLV()
self.ops[0xB9] = lambda: self.LDA(self.absolute_y_mode())
self.ops[0xBA] = lambda: self.TSX()
self.ops[0xBC] = lambda: self.LDY(self.absolute_x_mode())
self.ops[0xBD] = lambda: self.LDA(self.absolute_x_mode())
self.ops[0xBE] = lambda: self.LDX(self.absolute_y_mode())
self.ops[0xC0] = lambda: self.CPY(self.immediate_mode())
self.ops[0xC1] = lambda: self.CMP(self.indirect_x_mode())
self.ops[0xC4] = lambda: self.CPY(self.zero_page_mode())
self.ops[0xC5] = lambda: self.CMP(self.zero_page_mode())
self.ops[0xC6] = lambda: self.DEC(self.zero_page_mode())
self.ops[0xC8] = lambda: self.INY()
self.ops[0xC9] = lambda: self.CMP(self.immediate_mode())
self.ops[0xCA] = lambda: self.DEX()
self.ops[0xCC] = lambda: self.CPY(self.absolute_mode())
self.ops[0xCD] = lambda: self.CMP(self.absolute_mode())
self.ops[0xCE] = lambda: self.DEC(self.absolute_mode())
self.ops[0xD0] = lambda: self.BNE(self.relative_mode())
self.ops[0xD1] = lambda: self.CMP(self.indirect_y_mode())
self.ops[0xD5] = lambda: self.CMP(self.zero_page_x_mode())
self.ops[0xD6] = lambda: self.DEC(self.zero_page_x_mode())
self.ops[0xD8] = lambda: self.CLD()
self.ops[0xD9] = lambda: self.CMP(self.absolute_y_mode())
self.ops[0xDD] = lambda: self.CMP(self.absolute_x_mode())
self.ops[0xDE] = lambda: self.DEC(self.absolute_x_mode(rmw=True))
self.ops[0xE0] = lambda: self.CPX(self.immediate_mode())
self.ops[0xE1] = lambda: self.SBC(self.indirect_x_mode())
self.ops[0xE4] = lambda: self.CPX(self.zero_page_mode())
self.ops[0xE5] = lambda: self.SBC(self.zero_page_mode())
self.ops[0xE6] = lambda: self.INC(self.zero_page_mode())
self.ops[0xE8] = lambda: self.INX()
self.ops[0xE9] = lambda: self.SBC(self.immediate_mode())
self.ops[0xEA] = lambda: self.NOP()
self.ops[0xEC] = lambda: self.CPX(self.absolute_mode())
self.ops[0xED] = lambda: self.SBC(self.absolute_mode())
self.ops[0xEE] = lambda: self.INC(self.absolute_mode())
self.ops[0xF0] = lambda: self.BEQ(self.relative_mode())
self.ops[0xF1] = lambda: self.SBC(self.indirect_y_mode())
self.ops[0xF5] = lambda: self.SBC(self.zero_page_x_mode())
self.ops[0xF6] = lambda: self.INC(self.zero_page_x_mode())
self.ops[0xF8] = lambda: self.SED()
self.ops[0xF9] = lambda: self.SBC(self.absolute_y_mode())
self.ops[0xFD] = lambda: self.SBC(self.absolute_x_mode())
self.ops[0xFE] = lambda: self.INC(self.absolute_x_mode(rmw=True))
def reset(self):
self.program_counter = self.read_word(self.RESET_VECTOR)
def run(self, bus_port):
global bus
bus = socket.socket()
bus.connect(("127.0.0.1", bus_port))
while True:
self.cycles += 2 # all instructions take this as a minimum
op = self.read_pc_byte()
func = self.ops[op]
if func is None:
print "UNKNOWN OP"
print hex(self.program_counter - 1)
print hex(op)
break
else:
self.ops[op]()
def test_run(self, start, end):
self.program_counter = start
while True:
self.cycles += 2 # all instructions take this as a minimum
if self.program_counter == end:
break
op = self.read_pc_byte()
func = self.ops[op]
if func is None:
print "UNKNOWN OP"
print hex(self.program_counter - 1)
print hex(op)
break
else:
self.ops[op]()
####
def get_pc(self, inc=1):
pc = self.program_counter
self.program_counter += inc
return pc
def read_byte(self, address):
return self.memory.read_byte(self.cycles, address)
def read_word(self, address):
return self.memory.read_word(self.cycles, address)
def read_word_bug(self, address):
return self.memory.read_word_bug(self.cycles, address)
def read_pc_byte(self):
return self.read_byte(self.get_pc())
def read_pc_word(self):
return self.read_word(self.get_pc(2))
def write_byte(self, address, value):
self.memory.write_byte(self.cycles, address, value)
####
def status_from_byte(self, status):
self.carry_flag = [0, 1][0 != status & 1]
self.zero_flag = [0, 1][0 != status & 2]
self.interrupt_disable_flag = [0, 1][0 != status & 4]
self.decimal_mode_flag = [0, 1][0 != status & 8]
self.break_flag = [0, 1][0 != status & 16]
self.overflow_flag = [0, 1][0 != status & 64]
self.sign_flag = [0, 1][0 != status & 128]
def status_as_byte(self):
return self.carry_flag | self.zero_flag << 1 | self.interrupt_disable_flag << 2 | self.decimal_mode_flag << 3 | self.break_flag << 4 | 1 << 5 | self.overflow_flag << 6 | self.sign_flag << 7
####
def push_byte(self, byte):
self.write_byte(self.STACK_PAGE + self.stack_pointer, byte)
self.stack_pointer = (self.stack_pointer - 1) % 0x100
def pull_byte(self):
self.stack_pointer = (self.stack_pointer + 1) % 0x100
return self.read_byte(self.STACK_PAGE + self.stack_pointer)
def push_word(self, word):
hi, lo = divmod(word, 0x100)
self.push_byte(hi)
self.push_byte(lo)
def pull_word(self):
s = self.STACK_PAGE + self.stack_pointer + 1
self.stack_pointer += 2
return self.read_word(s)
####
def immediate_mode(self):
return self.get_pc()
def absolute_mode(self):
self.cycles += 2
return self.read_pc_word()
def absolute_x_mode(self, rmw=False):
if rmw:
self.cycles += 1
return self.absolute_mode() + self.x_index
def absolute_y_mode(self, rmw=False):
if rmw:
self.cycles += 1
return self.absolute_mode() + self.y_index
def zero_page_mode(self):
self.cycles += 1
return self.read_pc_byte()
def zero_page_x_mode(self):
self.cycles += 1
return (self.zero_page_mode() + self.x_index) % 0x100
def zero_page_y_mode(self):
self.cycles += 1
return (self.zero_page_mode() + self.y_index) % 0x100
def indirect_mode(self):
self.cycles += 2
return self.read_word_bug(self.absolute_mode())
def indirect_x_mode(self):
self.cycles += 4
return self.read_word_bug((self.read_pc_byte() + self.x_index) % 0x100)
def indirect_y_mode(self, rmw=False):
if rmw:
self.cycles += 4
else:
self.cycles += 3
return self.read_word_bug(self.read_pc_byte()) + self.y_index
def relative_mode(self):
pc = self.get_pc()
return pc + 1 + signed(self.read_byte(pc))
####
def update_nz(self, value):
value = value % 0x100
self.zero_flag = [0, 1][(value == 0)]
self.sign_flag = [0, 1][((value & 0x80) != 0)]
return value
def update_nzc(self, value):
self.carry_flag = [0, 1][(value > 0xFF)]
return self.update_nz(value)
####
# LOAD / STORE
def LDA(self, operand_address):
self.accumulator = self.update_nz(self.read_byte(operand_address))
def LDX(self, operand_address):
self.x_index = self.update_nz(self.read_byte(operand_address))
def LDY(self, operand_address):
self.y_index = self.update_nz(self.read_byte(operand_address))
def STA(self, operand_address):
self.write_byte(operand_address, self.accumulator)
def STX(self, operand_address):
self.write_byte(operand_address, self.x_index)
def STY(self, operand_address):
self.write_byte(operand_address, self.y_index)
# TRANSFER
def TAX(self):
self.x_index = self.update_nz(self.accumulator)
def TXA(self):
self.accumulator = self.update_nz(self.x_index)
def TAY(self):
self.y_index = self.update_nz(self.accumulator)
def TYA(self):
self.accumulator = self.update_nz(self.y_index)
def TSX(self):
self.x_index = self.update_nz(self.stack_pointer)
def TXS(self):
self.stack_pointer = self.x_index
# SHIFTS / ROTATES
def ASL(self, operand_address=None):
if operand_address is None:
self.accumulator = self.update_nzc(self.accumulator << 1)
else:
self.cycles += 2
self.write_byte(operand_address, self.update_nzc(self.read_byte(operand_address) << 1))
def ROL(self, operand_address=None):
if operand_address is None:
a = self.accumulator << 1
if self.carry_flag:
a = a | 0x01
self.accumulator = self.update_nzc(a)
else:
self.cycles += 2
m = self.read_byte(operand_address) << 1
if self.carry_flag:
m = m | 0x01
self.write_byte(operand_address, self.update_nzc(m))
def ROR(self, operand_address=None):
if operand_address is None:
if self.carry_flag:
self.accumulator = self.accumulator | 0x100
self.carry_flag = self.accumulator % 2
self.accumulator = self.update_nz(self.accumulator >> 1)
else:
self.cycles += 2
m = self.read_byte(operand_address)
if self.carry_flag:
m = m | 0x100
self.carry_flag = m % 2
self.write_byte(operand_address, self.update_nz(m >> 1))
def LSR(self, operand_address=None):
if operand_address is None:
self.carry_flag = self.accumulator % 2
self.accumulator = self.update_nz(self.accumulator >> 1)
else:
self.cycles += 2
self.carry_flag = self.read_byte(operand_address) % 2
self.write_byte(operand_address, self.update_nz(self.read_byte(operand_address) >> 1))
# JUMPS / RETURNS
def JMP(self, operand_address):
self.cycles -= 1
self.program_counter = operand_address
def JSR(self, operand_address):
self.cycles += 2
self.push_word(self.program_counter - 1)
self.program_counter = operand_address
def RTS(self):
self.cycles += 4
self.program_counter = self.pull_word() + 1
# BRANCHES
def BCC(self, operand_address):
if not self.carry_flag:
self.cycles += 1
self.program_counter = operand_address
def BCS(self, operand_address):
if self.carry_flag:
self.cycles += 1
self.program_counter = operand_address
def BEQ(self, operand_address):
if self.zero_flag:
self.cycles += 1
self.program_counter = operand_address
def BNE(self, operand_address):
if not self.zero_flag:
self.cycles += 1
self.program_counter = operand_address
def BMI(self, operand_address):
if self.sign_flag:
self.cycles += 1
self.program_counter = operand_address
def BPL(self, operand_address):
if not self.sign_flag:
self.cycles += 1
self.program_counter = operand_address
def BVC(self, operand_address):
if not self.overflow_flag:
self.cycles += 1
self.program_counter = operand_address
def BVS(self, operand_address):
if self.overflow_flag:
self.cycles += 1
self.program_counter = operand_address
# SET / CLEAR FLAGS
def CLC(self):
self.carry_flag = 0
def CLD(self):
self.decimal_mode_flag = 0
def CLI(self):
self.interrupt_disable_flag = 0
def CLV(self):
self.overflow_flag = 0
def SEC(self):
self.carry_flag = 1
def SED(self):
self.decimal_mode_flag = 1
def SEI(self):
self.interrupt_disable_flag = 1
# INCREMENT / DECREMENT
def DEC(self, operand_address):
self.cycles += 2
self.write_byte(operand_address, self.update_nz(self.read_byte(operand_address) - 1))
def DEX(self):
self.x_index = self.update_nz(self.x_index - 1)
def DEY(self):
self.y_index = self.update_nz(self.y_index - 1)
def INC(self, operand_address):
self.cycles += 2
self.write_byte(operand_address, self.update_nz(self.read_byte(operand_address) + 1))
def INX(self):
self.x_index = self.update_nz(self.x_index + 1)
def INY(self):
self.y_index = self.update_nz(self.y_index + 1)
# PUSH / PULL
def PHA(self):
self.cycles += 1
self.push_byte(self.accumulator)
def PHP(self):
self.cycles += 1
self.push_byte(self.status_as_byte())
def PLA(self):
self.cycles += 2
self.accumulator = self.update_nz(self.pull_byte())
def PLP(self):
self.cycles += 2
self.status_from_byte(self.pull_byte())
# LOGIC
def AND(self, operand_address):
self.accumulator = self.update_nz(self.accumulator & self.read_byte(operand_address))
def ORA(self, operand_address):
self.accumulator = self.update_nz(self.accumulator | self.read_byte(operand_address))
def EOR(self, operand_address):
self.accumulator = self.update_nz(self.accumulator ^ self.read_byte(operand_address))
# ARITHMETIC
def ADC(self, operand_address):
# @@@ doesn't handle BCD yet
assert not self.decimal_mode_flag
a2 = self.accumulator
a1 = signed(a2)
m2 = self.read_byte(operand_address)
m1 = signed(m2)
# twos complement addition
result1 = a1 + m1 + self.carry_flag
# unsigned addition
result2 = a2 + m2 + self.carry_flag
self.accumulator = self.update_nzc(result2)
# perhaps this could be calculated from result2 but result1 is more intuitive
self.overflow_flag = [0, 1][(result1 > 127) | (result1 < -128)]
def SBC(self, operand_address):
# @@@ doesn't handle BCD yet
assert not self.decimal_mode_flag
a2 = self.accumulator
a1 = signed(a2)
m2 = self.read_byte(operand_address)
m1 = signed(m2)
# twos complement subtraction
result1 = a1 - m1 - [1, 0][self.carry_flag]
# unsigned subtraction
result2 = a2 - m2 - [1, 0][self.carry_flag]
self.accumulator = self.update_nz(result2)
self.carry_flag = [0, 1][(result2 >= 0)]
# perhaps this could be calculated from result2 but result1 is more intuitive
self.overflow_flag = [0, 1][(result1 > 127) | (result1 < -128)]
# BIT
def BIT(self, operand_address):
value = self.read_byte(operand_address)
self.sign_flag = ((value >> 7) % 2) # bit 7
self.overflow_flag = ((value >> 6) % 2) # bit 6
self.zero_flag = [0, 1][((self.accumulator & value) == 0)]
# COMPARISON
def CMP(self, operand_address):
result = self.accumulator - self.read_byte(operand_address)
self.carry_flag = [0, 1][(result >= 0)]
self.update_nz(result)
def CPX(self, operand_address):
result = self.x_index - self.read_byte(operand_address)
self.carry_flag = [0, 1][(result >= 0)]
self.update_nz(result)
def CPY(self, operand_address):
result = self.y_index - self.read_byte(operand_address)
self.carry_flag = [0, 1][(result >= 0)]
self.update_nz(result)
# SYSTEM
def NOP(self):
pass
def BRK(self):
self.cycles += 5
self.push_word(self.program_counter + 1)
self.push_byte(self.status_as_byte())
self.program_counter = self.read_word(0xFFFE)
self.break_flag = 1
def RTI(self):
self.cycles += 4
self.status_from_byte(self.pull_byte())
self.program_counter = self.pull_word()
# @@@ IRQ
# @@@ NMI
def usage():
print >>sys.stderr, "ApplePy - an Apple ][ emulator in Python"
print >>sys.stderr, "James Tauber / http://jtauber.com/"
print >>sys.stderr
print >>sys.stderr, "Usage: cpu6502.py [options]"
print >>sys.stderr
print >>sys.stderr, " -b, --bus Bus port number"
print >>sys.stderr, " -R, --rom ROM file to use (default A2ROM.BIN)"
print >>sys.stderr, " -r, --ram RAM file to load (default none)"
sys.exit(1)
def get_options():
class Options:
def __init__(self):
self.rom = "A2ROM.BIN"
self.ram = None
self.bus = None
options = Options()
a = 1
while a < len(sys.argv):
if sys.argv[a].startswith("-"):
if sys.argv[a] in ("-b", "--bus"):
a += 1
options.bus = int(sys.argv[a])
elif sys.argv[a] in ("-R", "--rom"):
a += 1
options.rom = sys.argv[a]
elif sys.argv[a] in ("-r", "--ram"):
a += 1
options.ram = sys.argv[a]
else:
usage()
else:
usage()
a += 1
return options
if __name__ == "__main__":
options = get_options()
if options.bus is None:
print "ApplePy cpu core"
print "Run applepy.py instead"
sys.exit(0)
mem = Memory(options)
cpu = CPU(mem)
cpu.run(options.bus)
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