def assemble_extended_direct_operand(self, operand, opcode_key, statement,
opcode_bytes):
if isinstance(operand.address, Label):
result = self.assemble_label_operand(operand.address)
else:
result = (hi(operand.address), lo(operand.address))
return bytes(result)
def value_to_bytes(self, unsigned_offset, operand_bytes_length):
if operand_bytes_length == 1:
result = bytes((unsigned_offset, ))
elif operand_bytes_length == 2:
result = bytes((hi(unsigned_offset), lo(unsigned_offset)))
else:
assert False, f"Unexpected operand bytes length {operand_bytes_length}"
return result
def _(statement, asm):
operand = statement.operand
opcodes = OPCODES[statement.mnemonic]
opcode_key = single(operand.codes & opcodes.keys())
opcode = opcodes[opcode_key]
asm._opcode_bytes = (opcode, ) if opcode <= 0xFF else (hi(opcode),
lo(opcode))
operand_bytes = assemble_operand(operand, opcode_key, asm, statement)
asm._extend(asm._opcode_bytes + operand_bytes)
def assemble_label_operand(self, label):
if label.name in self._label_addresses:
target_address = self._label_addresses[label.name]
self._unresolved_labels.discard(label)
result = (hi(target_address), lo(target_address))
else:
self._more_passes_required = True
self._unresolved_labels.add(label)
result = (0, 0)
self._unreferenced_labels.discard(label)
return result
def assemble_immediate_operand(self, operand, opcode_key, statement,
opcode_bytes):
if isinstance(operand, Label):
result = self.assemble_label_operand(operand)
else:
assert statement.inherent_register.width in {1, 2}
if statement.inherent_register.width == 1:
result = (operand.value, )
elif statement.inherent_register.width == 2:
result = (hi(operand.value), lo(operand.value))
else:
assert False, f"Unexpected inherent register width {statement.inherent_register.width}"
return bytes(result)
def _(operand, opcode_key, asm, statement):
# If we know the address of the label, use it
if operand.name in asm._label_addresses:
target_address = asm._label_addresses[operand.name]
if opcode_key in branch_operand_widths:
operand_bytes_length = branch_operand_widths[opcode_key]
offset = target_address - asm.pos - len(
asm._opcode_bytes) - operand_bytes_length
unsigned_offset = twos_complement(offset, operand_bytes_length * 8)
if opcode_key == REL8:
return (unsigned_offset, )
elif opcode_key == REL16:
return (hi(unsigned_offset), lo(unsigned_offset))
else:
assert opcode_key is IMM
return (hi(target_address), lo(target_address))
else:
asm._more_passes_required = True
if opcode_key in branch_operand_widths:
return (0, ) * branch_operand_widths[opcode_key]
else:
assert opcode_key is IMM
return (0, 0)
def assemble_indexed_operand(self, operand: Indexed, opcode_key, statement,
opcode_bytes):
if operand.base in RR:
rr = RR[operand.base]
if operand.offset in ACCUMULATOR_OFFSET_POST_BYTE:
# Accumulator offset
post_byte = ACCUMULATOR_OFFSET_POST_BYTE[operand.offset]
post_byte |= rr << 5
return bytes((post_byte, ))
elif isinstance(operand.offset, Integral):
if operand.offset == 0:
post_byte = 0b10000100
post_byte |= rr << 5
return bytes((post_byte, ))
elif -16 <= operand.offset <= +15:
# 5-bit offset
post_byte = twos_complement(operand.offset, 5)
post_byte |= rr << 5
return bytes((post_byte, ))
elif -128 <= operand.offset <= +127:
# 8-bit offset
post_byte = 0b10001000
post_byte |= rr << 5
offset_byte = twos_complement(operand.offset, 8)
return bytes((post_byte, offset_byte))
elif -32768 <= operand.offset <= +32767:
# 16-bit offset
post_byte = 0b10001001
post_byte |= rr << 5
offset_bytes = twos_complement(operand.offset, 16)
return bytes(
(post_byte, hi(offset_bytes), lo(offset_bytes)))
else:
raise ValueError(
f"Cannot use indexed addressing offset {operand.offset} with base {operand.base}"
)
elif isinstance(operand.base, AutoIncrementedRegister):
if operand.base.register not in RR:
raise ValueError(
f"Cannot use auto pre-/post- increment or decrement with register {operand.base.register}"
)
rr = RR[operand.base.register]
post_byte = INDEX_CREMENT_POST_BYTE[operand.base.delta]
post_byte |= rr << 5
return bytes((post_byte, ))
else:
raise ValueError(
f"Cannot use {operand.base} as a base register for indexed addressing modes"
)
def _(operand, opcode_key, asm, statement):
assert statement.inherent_register.width in {1, 2}
if statement.inherent_register.width == 1:
return (operand.value, )
elif statement.inherent_register.width == 2:
return (hi(operand.value), lo(operand.value))