def _resolve(self, uref):
"""
Resolve the given unresolved reference. Get the symbol's value or
re-evaluate an expression and place that value in the reference's
address.
"""
if uref.expr is None:
value = self.meta.lookup(uref.ref)
else:
value = uref.expr.eval(self.meta)
if uref.type == REFERENCE_VALUE:
self.mem[uref.address] = vm.size8(value)
elif uref.type == REFERENCE_ABSOLUTE:
self.mem[uref.address::2] = vm.size16(value)
elif uref.type == REFERENCE_ZERO_PAGE:
self.mem[uref.address] = vm.size8(value)
elif uref.type == REFERENCE_RELATIVE:
abs_address = vm.size16(value)
# Branch is relative to PC after opcode and displacement
# have been consumed. Since abs_address points to where
# the displacement should go, add one to this value.
rel_address = abs_address - (uref.address + 1)
assert_branch_displacement(rel_address)
self.mem[uref.address] = vm.twos_forward(rel_address)
else:
assert False
def _getitem_single(self, index):
"""
Notifies listeners for each byte load and calls abstract _load
"""
value = self._load(vm.size16(index))
[listener(index, value) for listener in self.load_listeners]
return value
def r(self, address=None):
if address is None:
address = self.meta['PROGRAM_START']
address = vm.size16(self.meta[address])
self.cpu.push2(self.meta['MONITOR'] - 1)
istart(self.comp, address)
if self.cpu.exit != x6502.EXIT_MONITOR:
print str(self.cpu)
def map(self, block, address, name):
"""
Maps the *block* to the given *address* and assigns it with *name*.
If the *name* is already in use, a :class:`ValueException` is raised.
Raises an :class:`OverflowError` if the address is not in the allowable
range.
"""
if name in self._block_by_name:
raise ValueError('Block with name {} already exists'.format(name))
self._blocks += [(block, vm.size16(address))]
self._block_by_name[name] = block
def _setitem_single(self, index, value):
"""
Notifies listeners for each byte store and calls abstract _load.
Emits warning if read only.
"""
if self.read_only:
raise ReadOnlyError('Write {} to read-only location {}'
.format(vm.hex8(value), vm.hex16(index)))
else:
self._store(vm.size16(index), value)
[listener(index, value) for listener in self.store_listeners]
def label(self, name, address=None):
"""
Defines a the label, *name*, at *address*. If *address* is not
specified, the current position of the assembler is used. Raises an
:class:`OverflowError` if the address is out of range.
"""
if address is None:
address = self.position
self._check_meta()
resolved = self.meta.define_label(name, vm.size16(address))
map(self._resolve, resolved)
def load(self):
"""
Loads a byte from the current position and advances the position by
one. If *increment_first* is ``True``, the position is advanced
before loading the byte. Raises an :class:`OverflowError` if the
:attr:`position` is invalid.
"""
if self.increment_first:
self.position += 1
value = self.mem[vm.size16(self.position)]
if not self.increment_first:
self.position += 1
return value
def load2(self):
"""
Loads a word from the current position and advances the position by
two. If *increment_first* is ``True``, the position is advanced
before loading the word. Raises an :class:`OverflowError` if the
:attr:`position` is invalid.
"""
if self.increment_first:
self.position += 1
value = self.mem[vm.size16(self.position)::2]
if self.increment_first:
self.position += 1
else:
self.position += 2
return value
def define_label(self, name, address, reserved=False):
"""
Defines a label, *name*, for *address*. Raises a
:class:`SymbolConflictError` if an alias or label with the same name is
already defined. Raises a :class:`OverflowError` if *address* is not a
16-bit value. If *reserved* is ``True``, the alias cannot be removed
once added. If this definition resolves references, a list of addresses
where unresolved references exist is returned, otherwise an empty list
is returned.
"""
address = vm.size16(address)
resolvable = self._check_symbol(name, reserved)
self.labels[name] = address
self.addresses[address].add(name)
return resolvable
def next(self):
"""
Description
"""
d = Disassembled()
d.address = vm.size16(self.position)
d.labels = self.meta.get_labels(d.address)
d.remarks = self.meta.get_remarks(d.address)
d.argument = self.meta.get_argument(d.address)
d.data = self.meta.get_data(d.address)
if d.data is not None:
self.position = d.data.address + d.data.length
return d
opcode = self.pc.load()
if opcode in self._opcodes:
i = self._opcodes[opcode]
else:
op = '?{:02X}'.format(opcode)
i = x6502.Instruction(opcode, op, am.IMP, None)
d.instruction = i
if i.addressing_mode in AM_ADDRESS_16:
arg = self.pc.load2()
d.bytes = [opcode, vm.lb(arg), vm.hb(arg)]
elif (i.addressing_mode in AM_ADDRESS_8 or
i.addressing_mode in (am.REL, am.IMM)):
arg = self.pc.load()
if i.addressing_mode == am.REL and d.argument is None:
# Branch is displacement after consuming bytes, therefore
# add two.
d.argument = vm.hex16(d.address + vm.twos_inverse(arg) + 2)
d.bytes = [opcode, arg]
elif i.addressing_mode in AM_NO_ARGUMENT:
d.bytes = [opcode]
else:
assert False
return d
def test_size16_negative(self):
self.assertEquals(vm.SWORD_MIN, vm.size16(vm.SWORD_MIN))
def test_size16(self):
self.assertEquals(0xffff, vm.size16(0xffff))
def assemble(self, *args):
"""
To assemble an instruction, call the object with the
:class:`instruction <mach8.instruction.Instruction>` and the
argument (if necessary). Example::
a = Assembler(mem, position=0x4000)
_; a(lda_imm, 0x42)
Call the object with a string to create a label at the current address.
Forward references allowed. Example::
_; a(jmp_abs, 'skip_brk')
_; a(brk)
_; a('skip_brk')
_; a(nop)
Use :mod:`expressions <mach8.expressions>` for enhanced disassembly
display::
_; a(lda_imm, 9 + 2) # Disassembles to lda #$0B
_; a(lda_imm, add(9, 2)) # Disassembles to lda #[9 + 2]
Returns the address where the instruction was assembled.
Note: Any reference to a label or alias that does not exist is
considered to be an unresolved reference and will be entered in as a
zero until resolved. Invoking :meth:`verify` will raise a
:class:`SymbolUnresolvedError` if there are any outstanding unresolved
references.
"""
instruction_address = self.position
if len(args) == 0:
return instruction_address
# Label definition
if isinstance(args[0], str):
if len(args) != 1:
raise TypeError('Expected 1 argument but received {:d}'
.format(len(args)))
label = args[0]
self.label(label)
return
inst = args[0]
required_args = 1 if inst.addressing_mode in AM_NO_ARGUMENT else 2
if len(args) != required_args:
raise TypeError('Expected {:d} arguments but received {:d}'
.format(required_args, len(args)))
self._check_meta()
if inst.addressing_mode in AM_ADDRESS_16:
self.meta.clear(instruction_address + 1,
instruction_address + 3)
address = self.meta.add_reference(args[1], instruction_address,
REFERENCE_ABSOLUTE)
address = vm.size16(address)
self._pc.store(inst.opcode)
self._pc.store2(address)
elif inst.addressing_mode in AM_ADDRESS_8:
self.meta.clear(instruction_address + 1,
instruction_address + 2)
address = self.meta.add_reference(args[1], instruction_address,
REFERENCE_ZERO_PAGE)
address = vm.size8(address)
self._pc.store(inst.opcode)
self._pc.store(address)
elif inst.addressing_mode == am.IMM:
self.meta.clear(instruction_address + 1,
instruction_address + 2)
value = self.meta.add_reference(args[1], instruction_address,
REFERENCE_VALUE)
value = vm.size8s(value)
self._pc.store(inst.opcode)
self._pc.store(vm.mask8(value))
elif inst.addressing_mode in AM_NO_ARGUMENT:
self._pc.store(inst.opcode)
elif inst.addressing_mode == am.REL:
self.meta.clear(instruction_address + 1,
instruction_address + 2)
abs_address = self.meta.add_reference(args[1], instruction_address,
REFERENCE_RELATIVE)
if self.meta.lookup(args[1], default=None) is not None:
# Branch is relative to PC after instruction has been consumed.
# Since we have not yet 'consumed' it, the PC has to be
# adjusted by two (opcode and offset)
rel_address = abs_address - (self.position + 2)
assert_branch_displacement(rel_address)
# TODO: Cleanup
address = rel_address & vm.BITS8
else:
address = 0
self._pc.store(inst.opcode)
self._pc.store(address)
else:
raise ValueError('Invalid instruction: ' + str(inst))
self._new_position = True
