def ini_registers(self):
self.b = Register(self)
self.c = Register(self)
self.bc = DoubleRegister(self, self.b, self.c, constants.RESET_BC)
self.d = Register(self)
self.e = Register(self)
self.de = DoubleRegister(self, self.d, self.e, constants.RESET_DE)
self.h = Register(self)
self.l = Register(self)
self.hl = DoubleRegister(self, self.h, self.l, constants.RESET_HL)
self.hli = ImmediatePseudoRegister(self, self.hl)
self.pc = ReservedDoubleRegister(self, reset_value=constants.RESET_PC)
self.sp = ReservedDoubleRegister(self, reset_value=constants.RESET_SP)
self.a = Register(self, constants.RESET_A)
self.flag = FlagRegister(self, constants.RESET_F)
self.af = DoubleRegister(self, self.a, self.flag)
class CPU(object):
"""
PyGIRL GameBoy (TM) Emulator
Central Unit Processor_a (Sharp LR35902 CPU)
"""
def __init__(self, interrupt, memory):
assert isinstance(interrupt, Interrupt)
self.interrupt = interrupt
self.memory = memory
self.ime = False
self.halted = False
self.cycles = 0
self.ini_registers()
self.rom = [0]
self.reset()
def ini_registers(self):
self.b = Register(self)
self.c = Register(self)
self.bc = DoubleRegister(self, self.b, self.c, constants.RESET_BC)
self.d = Register(self)
self.e = Register(self)
self.de = DoubleRegister(self, self.d, self.e, constants.RESET_DE)
self.h = Register(self)
self.l = Register(self)
self.hl = DoubleRegister(self, self.h, self.l, constants.RESET_HL)
self.hli = ImmediatePseudoRegister(self, self.hl)
self.pc = ReservedDoubleRegister(self, reset_value=constants.RESET_PC)
self.sp = ReservedDoubleRegister(self, reset_value=constants.RESET_SP)
self.a = Register(self, constants.RESET_A)
self.flag = FlagRegister(self, constants.RESET_F)
self.af = DoubleRegister(self, self.a, self.flag)
def reset(self):
self.reset_registers()
self.flag.reset()
self.flag.is_zero = True
self.ime = False
self.halted = False
self.cycles = 0
self.instruction_counter = 0
self.last_op_code = -1
self.last_fetch_execute_op_code = -1
def reset_registers(self):
self.a.reset()
self.flag.reset()
self.bc.reset()
self.de.reset()
self.hl.reset()
self.sp.reset()
self.pc.reset()
# ---------------------------------------------------------------
def get_af(self):
return self.af
def get_a(self):
return self.a
def get_f(self):
return self.f
def get_bc(self):
return self.bc
def get_b(self):
return self.b
def get_c(self):
return self.c
def get_de(self):
return self.de
def get_d(self):
return self.d
def get_e(self):
return self.e
def get_hl(self):
return self.hl
def get_hli(self):
return self.hli
def get_h(self):
return self.h
def get_l(self):
return self.l
def get_sp(self):
return self.sp
def get_if(self):
val = 0x00
if self.ime:
val = 0x01
if self.halted:
val += 0x80
return val
def is_z(self):
""" zero flag"""
return self.flag.is_zero
def is_c(self):
""" carry flag, true if the result did not fit in the register"""
return self.flag.is_carry
def is_h(self):
""" half carry, carry from bit 3 to 4"""
return self.flag.is_half_carry
def is_n(self):
""" subtract flag, true if the last operation was a subtraction"""
return self.flag.is_subtraction
def isS(self):
return self.flag.s_flag
def is_p(self):
return self.flag.p_flag
def is_not_z(self):
return not self.is_z()
def is_not_c(self):
return not self.is_c()
def is_not_h(self):
return not self.is_h()
def is_not_n(self):
return not self.is_n()
def set_rom(self, banks):
self.rom = banks
# ---------------------------------------------------------------
def emulate(self, ticks):
self.cycles += ticks
self.handle_pending_interrupts()
while self.cycles > 0:
self.execute(self.fetch(use_cycles=False))
def emulate_step(self):
self.handle_pending_interrupts()
self.execute(self.fetch(use_cycles=False))
def handle_pending_interrupts(self):
if self.halted:
self.update_interrupt_cycles()
if self.ime and self.interrupt.is_pending():
self.lower_pending_interrupt()
def update_interrupt_cycles(self):
if self.interrupt.is_pending():
self.halted = False
self.cycles -= 4
elif self.cycles > 0:
self.cycles = 0
def lower_pending_interrupt(self):
for flag in self.interrupt.interrupt_flags:
if flag.is_pending():
self.ime = False
self.call(flag.call_code, use_cycles=False)
flag.set_pending(False)
return
def fetch_execute(self):
op_code = self.fetch()
self.last_fetch_execute_op_code = op_code
FETCH_EXECUTE_OP_CODES[op_code](self)
def execute(self, op_code):
self.instruction_counter += 1
self.last_op_code = op_code
OP_CODES[op_code](self)
# -------------------------------------------------------------------
def debug(self):
#print "0xDD called"
pass
def read(self, hi, lo=None):
# memory Access, 1 cycle
address = hi
if lo is not None:
address = (hi << 8) + lo
self.cycles -= 1
return self.memory.read(address)
def write(self, address, data):
# 2 cycles
self.memory.write(address, data)
self.cycles -= 2
def fetch(self, use_cycles=True):
# Fetching 1 cycle
if use_cycles:
self.cycles += 1
pc = self.pc.get(use_cycles)
if pc <= 0x3FFF:
data = self.rom[self.pc.get(use_cycles)]
else:
data = self.memory.read(self.pc.get(use_cycles))
self.pc.inc(use_cycles) # 2 cycles
return data
def fetch_double_address(self):
lo = self.fetch() # 1 cycle
hi = self.fetch() # 1 cycle
return (hi << 8) + lo
def fetch_double_register(self, register):
self.double_register_inverse_call(CPUFetchCaller(self), register)
self.cycles += 1
def push(self, data, use_cycles=True):
# Stack, 2 cycles
self.sp.dec(use_cycles) # 2 cycles
self.memory.write(self.sp.get(use_cycles), data)
def push_double_register(self, register, use_cycles=True):
# PUSH rr 4 cycles
self.push(register.get_hi(), use_cycles) # 2 cycles
self.push(register.get_lo(), use_cycles) # 2 cycles
def pop(self, use_cycles=True):
# 1 cycle
data = self.memory.read(self.sp.get())
self.sp.inc() # 2 cycles
self.cycles += 1
return data
def pop_double_register(self, register):
# 3 cycles
self.double_register_inverse_call(CPUPopCaller(self), register)
self.cycles += 1
def double_register_inverse_call(self, getCaller, register):
register.set_lo(getCaller.get()) # 2 cycles
register.set_hi(getCaller.get()) # 2 cycles
def call(self, address, use_cycles=True):
# 4 cycles
self.push_double_register(self.pc, use_cycles)
self.pc.set(address, use_cycles=use_cycles) # 1 cycle
if use_cycles:
self.cycles += 1
def load(self, getCaller, setCaller):
# 1 cycle
value = getCaller.get()
setCaller.set(value) # 1 cycle
def load_fetch_register(self, register):
self.load(CPUFetchCaller(self), RegisterCallWrapper(register))
def store_hl_in_pc(self):
# LD PC,HL, 1 cycle
self.load(DoubleRegisterCallWrapper(self.hl),
DoubleRegisterCallWrapper(self.pc))
def fetch_load(self, getCaller, setCaller):
self.load(CPUFetchCaller(self), setCaller)
def add_a(self, getCaller, setCaller=None):
# TODO: Test overflow -> carry flag
data = getCaller.get()
# ALU, 1 cycle
added = self.a.get() + data
self.add_sub_flag_finish(added, data)
def add_hl(self, register):
# 2 cycles
data = register.get()
added = (self.hl.get() + data) # 1 cycle
self.flag.partial_reset(keep_is_zero=True)
self.flag.is_half_carry = (((added ^ self.hl.get() ^ data) & 0x1000) != 0)
self.flag.is_carry = (added >= 0x10000 or added < 0)
self.hl.set(added & 0xFFFF)
self.cycles -= 1
def add_a_with_carry(self, getCaller, setCaller=None):
# 1 cycle
data = getCaller.get()
s = self.a.get() + data + int(self.flag.is_carry)
self.add_sub_flag_finish(s,data)
def subtract_with_carry_a(self, getCaller, setCaller=None):
# 1 cycle
data = getCaller.get()
s = self.a.get() - data - int(self.flag.is_carry)
self.add_sub_flag_finish(s, data)
self.flag.is_subtraction = True
def add_sub_flag_finish(self, s, data):
self.flag.reset()
# set the h flag if the 0x10 bit was affected
self.flag.is_half_carry = (((s ^ self.a.get() ^ data) & 0x10) != 0)
self.flag.is_carry = (s > 0xFF or s < 0)
self.flag.zero_check(s)
self.a.set(s & 0xFF) # 1 cycle
def subtract_a(self, getCaller, setCaller=None):
# 1 cycle
data = getCaller.get()
self.compare_a_simple(data)
self.a.sub(data, False)
def fetch_subtract_a(self):
data = self.fetch()
# 1 cycle
self.compare_a_simple(data) # 1 cycle
self.a.sub(data, False)
def compare_a(self, getCaller, setCaller=None):
# 1 cycle
self.compare_a_simple(getCaller.get())
def compare_a_simple(self, s):
s = (self.a.get() - s) & 0xFF
self.flag.reset()
self.flag.is_subtraction = True
self.flag.zero_check(s)
self.subtract_his_carry_finish(s)
self.cycles -= 1
def subtract_his_carry_finish(self, data):
self.flag.is_carry = (data > self.a.get())
self.flag.is_half_carry_compare(data, self.a.get())
def and_a(self, getCaller, setCaller=None):
# 1 cycle
self.a.set(self.a.get() & getCaller.get()) # 1 cycle
self.flag.reset()
self.flag.zero_check(self.a.get())
self.flag.is_half_carry = True
def xor_a(self, getCaller, setCaller=None):
# 1 cycle
self.a.set( self.a.get() ^ getCaller.get()) # 1 cycle
self.flag.reset()
self.flag.zero_check(self.a.get())
def or_a(self, getCaller, setCaller=None):
# 1 cycle
self.a.set(self.a.get() | getCaller.get()) # 1 cycle
self.flag.reset()
self.flag.zero_check(self.a.get())
def inc_double_register(self, register):
# INC rr
register.inc()
def dec_double_register(self, register):
# DEC rr
register.dec()
def inc(self, getCaller, setCaller):
# 1 cycle
data = (getCaller.get() + 1) & 0xFF
self.dec_inis_carry_finish(data, setCaller, 0x00)
def dec(self, getCaller, setCaller):
# 1 cycle
data = (getCaller.get() - 1) & 0xFF
self.dec_inis_carry_finish(data, setCaller, 0x0F)
self.flag.is_subtraction = True
def dec_inis_carry_finish(self, data, setCaller, compare):
self.flag.partial_reset(keep_is_carry=True)
self.flag.zero_check(data)
self.flag.is_half_carry = ((data & 0x0F) == compare)
setCaller.set(data) # 1 cycle
def rotate_left_circular(self, getCaller, setCaller):
# RLC 1 cycle
data = getCaller.get()
s = ((data << 1) & 0xFF) + ((data & 0x80) >> 7)
self.flags_and_setter_finish(s, data, setCaller, 0x80)
# self.cycles -= 1
def rotate_left_circular_a(self):
# RLCA rotate_left_circular_a 1 cycle
self.rotate_left_circular(RegisterCallWrapper(self.a),
RegisterCallWrapper(self.a))
def rotate_left(self, getCaller, setCaller):
# 1 cycle
data = getCaller.get()
s = ((data & 0x7F) << 1) + int(self.flag.is_carry)
self.flags_and_setter_finish(s, data, setCaller, 0x80) # 1 cycle
def rotate_left_a(self):
# RLA 1 cycle
self.rotate_left(RegisterCallWrapper(self.a),
RegisterCallWrapper(self.a))
def rotate_right_circular(self, getCaller, setCaller):
data = getCaller.get()
# RRC 1 cycle
s = (data >> 1) + ((data & 0x01) << 7)
self.flags_and_setter_finish(s, data, setCaller) # 1 cycle
def rotate_right_circular_a(self):
# RRCA 1 cycle
self.rotate_right_circular(RegisterCallWrapper(self.a),
RegisterCallWrapper(self.a))
def rotate_right(self, getCaller, setCaller):
# 1 cycle
data = getCaller.get()
s = (data >> 1)
if self.flag.is_carry:
s += 0x80
self.flags_and_setter_finish(s, data, setCaller) # 1 cycle
def rotate_right_a(self):
# RRA 1 cycle
self.rotate_right(RegisterCallWrapper(self.a),
RegisterCallWrapper(self.a))
def shift_left_arithmetic(self, getCaller, setCaller):
# 2 cycles
data = getCaller.get()
s = (data << 1) & 0xFF
self.flags_and_setter_finish(s, data, setCaller, 0x80) # 1 cycle
def shift_right_arithmetic(self, getCaller, setCaller):
data = getCaller.get()
# 1 cycle
s = (data >> 1) + (data & 0x80)
self.flags_and_setter_finish(s, data, setCaller) # 1 cycle
def shift_word_right_logical(self, getCaller, setCaller):
# 2 cycles
data = getCaller.get()
s = (data >> 1)
self.flags_and_setter_finish(s, data, setCaller) # 2 cycles
def flags_and_setter_finish(self, s, data, setCaller, compare_and=0x01):
# 2 cycles
s &= 0xFF
self.flag.reset()
self.flag.zero_check(s)
self.flag.is_carry_compare(data, compare_and)
setCaller.set(s) # 1 cycle
def swap(self, getCaller, setCaller):
# 1 cycle
data = getCaller.get()
s = ((data << 4) + (data >> 4)) & 0xFF
self.flag.reset()
self.flag.zero_check(s)
setCaller.set(s)
def test_bit(self, getCaller, setCaller, n):
# 1 cycle
self.flag.partial_reset(keep_is_carry=True)
self.flag.is_half_carry = True
self.flag.is_zero = ((getCaller.get() & (1 << n)) == 0)
self.cycles -= 1
def set_bit(self, getCaller, setCaller, n):
# 1 cycle
setCaller.set(getCaller.get() | (1 << n)) # 1 cycle
def reset_bit(self, getCaller, setCaller, n):
# 1 cycle
setCaller.set(getCaller.get() & (~(1 << n))) # 1 cycle
def store_fetched_memory_in_a(self):
# LD A,(nnnn), 4 cycles
self.a.set(self.read(self.fetch_double_address())) # 1+1 + 2 cycles
def write_a_at_bc_address(self):
# 2 cycles
self.write(self.bc.get(), self.a.get())
def write_a_at_de_address(self):
self.write(self.de.get(), self.a.get())
def store_memory_at_bc_in_a(self):
self.a.set(self.read(self.bc.get()))
def store_memory_at_de_in_a(self):
self.a.set(self.read(self.de.get()))
def ld_dbRegisteri_A(self, register):
# LD (rr),A 2 cycles
self.write(register.get(), self.a.get()) # 2 cycles
def load_mem_sp(self):
# LD (nnnn),SP 5 cycles
address = self.fetch_double_address() # 2 cycles
self.write(address, self.sp.get_lo()) # 2 cycles
self.write((address + 1), self.sp.get_hi()) # 2 cycles
self.cycles += 1
def store_a_at_fetched_address(self):
# LD (nnnn),A 4 cycles
self.write(self.fetch_double_address(), self.a.get()) # 2 cycles
def store_memory_at_expanded_fetch_address_in_a(self):
# LDH A,(nn) 3 cycles
self.a.set(self.read(0xFF00 + self.fetch())) # 1+1+1 cycles
def store_expanded_c_in_a(self):
# LDH A,(C) 2 cycles
self.a.set(self.read(0xFF00 + self.bc.get_lo())) # 1+2 cycles
def load_and_increment_a_hli(self):
# loadAndIncrement A,(HL) 2 cycles
self.a.set(self.read(self.hl.get())) # 2 cycles
self.hl.inc()# 2 cycles
self.cycles += 2
def load_and_decrement_a_hli(self):
# loadAndDecrement A,(HL) 2 cycles
self.a.set(self.read(self.hl.get())) # 2 cycles
self.hl.dec() # 2 cycles
self.cycles += 2
def write_a_at_expanded_fetch_address(self):
# LDH (nn),A 3 cycles
self.write(0xFF00 + self.fetch(), self.a.get()) # 2 + 1 cycles
def write_a_at_expanded_c_address(self):
# LDH (C),A 2 cycles
self.write(0xFF00 + self.c.get(), self.a.get()) # 2 cycles
def load_and_increment_hli_a(self):
# loadAndIncrement (HL),A 2 cycles
self.write(self.hl.get(), self.a.get()) # 2 cycles
self.hl.inc() # 2 cycles
self.cycles += 2
def load_and_decrement_hli_a(self):
# loadAndDecrement (HL),A 2 cycles
self.write(self.hl.get(), self.a.get()) # 2 cycles
self.hl.dec() # 2 cycles
self.cycles += 2
def store_hl_in_sp(self):
# LD SP,HL 2 cycles
self.sp.set(self.hl.get()) # 1 cycle
self.cycles -= 1
def complement_a(self):
# CPA
self.a.set(self.a.get() ^ 0xFF)
self.flag.is_subtraction = True
self.flag.is_half_carry = True
def decimal_adjust_a(self):
# DAA 1 cycle
delta = 0
if self.is_h():
delta |= 0x06
if self.is_c():
delta |= 0x60
if (self.a.get() & 0x0F) > 0x09:
delta |= 0x06
if (self.a.get() & 0xF0) > 0x80:
delta |= 0x60
if (self.a.get() & 0xF0) > 0x90:
delta |= 0x60
if not self.is_n():
self.a.set((self.a.get() + delta) & 0xFF) # 1 cycle
else:
self.a.set((self.a.get() - delta) & 0xFF) # 1 cycle
self.flag.partial_reset(keep_is_subtraction=True)
if delta >= 0x60:
self.flag.is_carry = True
self.flag.zero_check(self.a.get())
def increment_sp_by_fetch(self):
# ADD SP,nn 4 cycles
self.sp.set(self.get_fetchadded_sp()) # 1+1 cycle
self.cycles -= 2
def store_fetch_added_sp_in_hl(self):
# LD HL,SP+nn 3 cycles
self.hl.set(self.get_fetchadded_sp()) # 1+1 cycle
self.cycles -= 1
def get_fetchadded_sp(self):
# 1 cycle
offset = process_2s_complement(self.fetch()) # 1 cycle
s = (self.sp.get() + offset) & 0xFFFF
self.flag.reset()
if (offset >= 0):
self.flag.is_carry = (s < self.sp.get())
if (s & 0x0F00) < (self.sp.get() & 0x0F00):
self.flag.is_half_carry = True
else:
self.flag.is_carry = (s > self.sp.get())
if (s & 0x0F00) > (self.sp.get() & 0x0F00):
self.flag.is_half_carry = True
return s
def complement_carry_flag(self):
# CCF/SCF
self.flag.partial_reset(keep_is_zero=True, keep_is_carry=True)
self.flag.is_carry = not self.flag.is_carry
def set_carry_flag(self):
self.flag.partial_reset(keep_is_zero=True)
self.flag.is_carry = True
def nop(self):
# NOP 1 cycle
self.cycles -= 1
def jump(self):
# JP nnnn, 4 cycles
self.pc.set(self.fetch_double_address()) # 1+2 cycles
self.cycles -= 1
def conditional_jump(self, cc):
# JP cc,nnnn 3,4 cycles
if cc:
self.jump() # 4 cycles
else:
self.pc.add(2) # 3 cycles
def relative_jump(self):
# JR +nn, 3 cycles
self.pc.add(process_2s_complement(self.fetch())) # 3 + 1 cycles
self.cycles += 1
def relative_conditional_jump(self, cc):
# JR cc,+nn, 2,3 cycles
if cc:
self.relative_jump() # 3 cycles
else:
self.pc.inc() # 2 cycles
def unconditional_call(self):
# CALL nnnn, 6 cycles
self.call(self.fetch_double_address()) # 4+2 cycles
def conditional_call(self, cc):
# CALL cc,nnnn, 3,6 cycles
if cc:
self.unconditional_call() # 6 cycles
else:
self.pc.add(2) # 3 cycles
def ret(self):
# RET 4 cycles
self.double_register_inverse_call(CPUPopCaller(self), self.pc)
def conditional_return(self, cc):
# RET cc 2,5 cycles
if cc:
self.ret() # 4 cycles
# FIXME maybe this should be the same
self.cycles -= 1
else:
self.cycles -= 2
def return_from_interrupt(self):
# RETI 4 cycles
self.ret() # 4 cycles
self.cycles += 1
self.enable_interrupts()
def restart(self, nn):
# RST nn 4 cycles
self.call(nn) # 4 cycles
def disable_interrupts(self):
# DI/EI 1 cycle
self.ime = False
self.cycles -= 1
def enable_interrupts(self):
# 1 cycle
self.ime = True
self.execute(self.fetch())
self.handle_pending_interrupts()
def halt(self):
# HALT/STOP
self.halted = True
# emulate bug when interrupts are pending
if not self.ime and self.interrupt.is_pending():
self.execute(self.memory.read(self.pc.get()))
self.handle_pending_interrupts()
def stop(self):
# 0 cycles
self.cycles += 1
self.fetch()
