applepy/applepy.py
2011-08-07 00:39:17 -04:00

694 lines
25 KiB
Python

# ApplePy - an Apple ][ emulator in Python
# James Tauber / http://jtauber.com/
# originally written 2001, updated 2011
import curses
def signed(x):
if x > 0x7F:
x = x - 0x100
return x
class Memory:
def __init__(self, size):
self.__mem = [0x00] * size
def load(self, address, data):
for offset, datum in enumerate(data):
self.__mem[address + offset] = datum
def load_file(self, address, filename):
with open(filename) as f:
for offset, datum in enumerate(f.read()):
self.__mem[address + offset] = ord(datum)
def read_byte(self, address):
assert address <= 0xFFFF
if 0xC000 <= address <= 0xCFFF:
if address == 0xC010:
self.__mem[0xC000] = self.__mem[0xC000] & 0x7F # clear keyboard
return self.__mem[address]
def write_byte(self, address, value):
if 0x400 <= address < 0x800:
self.write_screen(address, value)
self.__mem[address] = value
def read_word(self, address):
return self.read_byte(address) + (self.read_byte(address + 1) << 8)
def write_screen(self, address, value):
base = address - 0x400
hi, lo = divmod(base, 0x80)
row_group, column = divmod(lo, 0x28)
row = hi + 8 * row_group
assert row_group != 3 # @@@
c = chr(0x20 + ((value + 0x20) % 0x40))
if value < 0x40:
attr = curses.A_DIM
elif value < 0x80:
attr = curses.A_REVERSE
elif value < 0xA0:
attr = curses.A_UNDERLINE
else:
attr = curses.A_DIM
self.win.addch(row, column, c, attr)
class CPU:
STACK_PAGE = 0x100
RESET_VECTOR = 0xFFFC
def __init__(self, memory):
self.memory = 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.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())
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())
self.ops[0x40] = lambda: self.RTI()
self.ops[0x41] = lambda: self.EOR(x.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())
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())
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())
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())
self.ops[0x98] = lambda: self.TYA()
self.ops[0x99] = lambda: self.STA(self.absolute_y_mode())
self.ops[0x9A] = lambda: self.TXS()
self.ops[0x9D] = lambda: self.STA(self.absolute_x_mode())
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())
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())
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())
def reset(self):
self.program_counter = self.memory.read_word(self.RESET_VECTOR)
def dump(self, win):
win.addstr(10, 50, "%04X got %02X" % (self.program_counter - 1, op))
win.addstr(14, 50, "BUFFER:" +
" ".join("%02X" % self.memory.read_byte(m) for m in range(0x200, 0x210))
)
win.addstr(11, 50, "A=%02X X=%02X Y=%02X S=%02X V=%02X B=%02X D=%02X I=%02X Z=%02X C=%02X PC=%04X S=%02X" % (
self.accumulator,
self.x_index,
self.y_index,
self.sign_flag,
self.overflow_flag,
self.break_flag,
self.decimal_mode_flag,
self.interrupt_disable_flag,
self.zero_flag,
self.carry_flag,
self.program_counter - 1,
self.stack_pointer))
win.addstr(12, 50, "STACK:" +
" ".join("%02X" % self.memory.read_byte(self.STACK_PAGE + i) for i in range(255, self.stack_pointer, -1))
)
def run(self, win):
self.memory.win = win
win.clear()
curses.noecho()
win.nodelay(True)
while True:
op = self.read_pc_byte()
# self.dump(win)
func = self.ops[op]
if func is None:
curses.endwin()
print "UNKNOWN OP"
print hex(self.program_counter - 1)
print hex(op)
break
else:
self.ops[op]()
try:
key = ord(win.getkey())
if key == 0xA:
key = 0xD
elif key == 0x7F:
key = 0x8
# win.addstr(15, 50, hex(key))
self.memory.write_byte(0xC000, 0x80 + key)
except curses.error:
pass
except TypeError:
pass
####
def get_pc(self, inc=1):
pc = self.program_counter
self.program_counter += inc
return pc
def read_pc_byte(self):
return self.memory.read_byte(self.get_pc())
def read_pc_word(self):
return self.memory.read_word(self.get_pc(2))
####
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.memory.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.memory.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.memory.read_word(s)
####
def immediate_mode(self):
return self.get_pc()
def absolute_mode(self):
return self.read_pc_word()
def absolute_x_mode(self):
return self.absolute_mode() + signed(self.x_index)
def absolute_y_mode(self):
return self.absolute_mode() + signed(self.y_index)
def zero_page_mode(self):
return self.read_pc_byte()
def zero_page_x_mode(self):
return (self.zero_page_mode() + signed(self.x_index)) % 0x100
def zero_page_y_mode(self):
return (self.zero_page_mode() + signed(self.y_index)) % 0x100
def indirect_mode(self):
address = self.absolute_mode()
hi = address + 1
# emulate a known bug in 6502
hi = (address & 0xFF00) + (((address & 0xFF) + 1) & 0xFF)
return self.memory.read_byte(address) + (self.memory.read_byte(hi) << 8)
def indirect_x_mode(self):
return self.memory.read_word((self.read_pc_byte() + signed(self.x_index)) % 0x100)
def indirect_y_mode(self):
return self.memory.read_word(self.read_pc_byte()) + signed(self.y_index)
def relative_mode(self):
pc = self.get_pc()
return pc + 1 + signed(self.memory.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.memory.read_byte(operand_address))
def LDX(self, operand_address):
self.x_index = self.update_nz(self.memory.read_byte(operand_address))
def LDY(self, operand_address):
self.y_index = self.update_nz(self.memory.read_byte(operand_address))
def STA(self, operand_address):
self.memory.write_byte(operand_address, self.accumulator)
def STX(self, operand_address):
self.memory.write_byte(operand_address, self.x_index)
def STY(self, operand_address):
self.memory.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.memory.write_byte(operand_address, self.update_nzc(self.memory.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:
m = self.memory.read_byte(operand_address) << 1
if self.carry_flag:
m = m | 0x01
self.memory.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:
m = self.memory.read_byte(operand_address)
if self.carry_flag:
m = m | 0x100
self.carry_flag = m % 2
self.memory.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.carry_flag = self.memory.read_byte(operand_address) % 2
self.memory.write_byte(operand_address, self.update_nz(self.memory.read_byte(operand_address) >> 1))
# JUMPS / RETURNS
def JMP(self, operand_address):
self.program_counter = operand_address
def JSR(self, operand_address):
self.push_word(self.program_counter - 1)
self.program_counter = operand_address
def RTS(self):
self.program_counter = self.pull_word() + 1
# BRANCHES
def BCC(self, operand_address):
if not self.carry_flag:
self.program_counter = operand_address
def BCS(self, operand_address):
if self.carry_flag:
self.program_counter = operand_address
def BEQ(self, operand_address):
if self.zero_flag:
self.program_counter = operand_address
def BNE(self, operand_address):
if not self.zero_flag:
self.program_counter = operand_address
def BMI(self, operand_address):
if self.sign_flag:
self.program_counter = operand_address
def BPL(self, operand_address):
if not self.sign_flag:
self.program_counter = operand_address
def BVC(self, operand_address):
if not self.overflow_flag:
self.program_counter = operand_address
def BVS(self, operand_address):
if self.overflow_flag:
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.memory.write_byte(operand_address, self.update_nz(self.memory.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.memory.write_byte(operand_address, self.update_nz(self.memory.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.push_byte(self.accumulator)
def PHP(self):
self.push_byte(self.status_as_byte())
def PLA(self):
self.accumulator = self.update_nz(self.pull_byte())
def PLP(self):
self.status_from_byte(self.pull_byte())
# LOGIC
def AND(self, operand_address):
self.accumulator = self.update_nz(self.accumulator & self.memory.read_byte(operand_address))
def ORA(self, operand_address):
self.accumulator = self.update_nz(self.accumulator | self.memory.read_byte(operand_address))
def EOR(self, operand_address):
self.accumulator = self.update_nz(self.accumulator ^ self.memory.read_byte(operand_address))
# ARITHMETIC
def ADC(self, operand_address):
# @@@ doesn't handle BCD yet
assert not self.decimal_mode_flag
a1 = a2 = self.accumulator
if a1 & 0x80:
a1 = (a1 & 0x7F) - 0x80
m1 = m2 = self.memory.read_byte(operand_address)
if m1 & 0x80:
m1 = (m1 & 0x7F) - 0x80
# 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
a1 = a2 = self.accumulator
if a1 & 0x80:
a1 = (a1 & 0x7F) - 0x80
m1 = m2 = self.memory.read_byte(operand_address)
if m1 & 0x80:
m1 = (m1 & 0x7F) - 0x80
# 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.memory.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.memory.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.memory.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.memory.read_byte(operand_address)
self.carry_flag = [0, 1][(result >= 0)]
self.update_nz(result)
# SYSTEM
def NOP(self):
pass
def BRK(self):
self.push_word(self.program_counter + 1)
self.push_byte(self.status_as_byte())
self.program_counter = self.memory.read_word(0xFFFE)
self.break_flag = 1
def RTI(self):
self.status_from_byte(self.pull_byte())
self.program_counter = self.pull_word()
# @@@ IRQ
# @@@ NMI
if __name__ == "__main__":
mem = Memory(0x100000)
# available from http://www.easy68k.com/paulrsm/6502/index.html
mem.load_file(0xD000, "A2ROM.BIN")
cpu = CPU(mem)
curses.wrapper(cpu.run)