from ...core.enum.ea_mode import EAMode
from ...core.enum.op_size import OpSize
from ...core.enum import ea_mode_bin
from ...core.enum.ea_mode_bin import parse_ea_from_binary
from ...simulator.m68k import M68K
from ...core.opcodes.opcode import Opcode
from ...core.util.split_bits import split_bits
from ...core.util import opcode_util
from ..util.parsing import parse_assembly_parameter
from ..models.assembly_parameter import AssemblyParameter
from ..enum.condition_status_code import ConditionStatusCode
from ..models.memory_value import MemoryValue
class Subq(Opcode): # Forward declaration
pass
[docs]class Subq(Opcode):
"""
SUBQ: Subtract Quick
Operation: Destination – Immediate Data → Destination
Syntax: SUBQ # < data > , < ea >
Attributes: Size = (Byte, Word, Long)
Description: Subtracts the immediate data (1 – 8) from the destination operand. The size
of the operation is specified as byte, word, or long. Only word and long operations can
be used with address registers, and the condition codes are not affected. When
subtracting from address registers, the entire destination address register is used,
despite the operation size.
Condition Codes:
X — Set to the value of the carry bit.
N — Set if the result is negative; cleared otherwise.
Z — Set if the result is zero; cleared otherwise.
V — Set if an overflow occurs; cleared otherwise.
C — Set if a borrow occurs; cleared otherwise.
Data field—Three bits of immediate data; 1 – 7 represent immediate values of 1 – 7,
and zero represents eight.
Size field—Specifies the size of the operation.
00 — Byte operation
01 — Word operation
10 — Long operation
"""
# Allowed sizes for this opcode
valid_sizes = [OpSize.BYTE, OpSize.WORD, OpSize.LONG]
def __init__(self, params: list, size: OpSize = OpSize.WORD):
assert len(params) == 2
assert isinstance(params[0], AssemblyParameter)
assert isinstance(params[1], AssemblyParameter)
# check src param is valid
assert params[0].mode == EAMode.IMM
self.src = params[0]
# check the dest param is valid. Can't be immediate data
assert params[1].mode != EAMode.IMM
self.dest = params[1]
assert size in Subq.valid_sizes
self.size = size
[docs] def assemble(self) -> bytearray:
"""
Assembles this opcode into hex to be inserted into memory
:return: The hex version of this opcode
"""
# 1101 Dn xxx D x S xx M xxx Xn xxx
# ret_opcode is the binary value which represents the assembled instruction
ret_opcode = 0b0101 << 12
ret_opcode |= self.src.data << 9
ret_opcode |= 0b1 << 8
if self.size == OpSize.BYTE:
ret_opcode |= 0b00 << 6
elif self.size == OpSize.WORD:
ret_opcode |= 0b01 << 6
elif self.size == OpSize.LONG:
ret_opcode |= 0b10 << 6
ret_opcode |= ea_mode_bin.parse_from_ea_mode_modefirst(self.dest) << 0
ret_bytes = bytearray(ret_opcode.to_bytes(2, byteorder='big', signed=False))
if self.dest.mode == EAMode.AWA or self.dest.mode == EAMode.ALA:
ret_bytes.extend(opcode_util.ea_to_binary_post_op(self.dest, self.size).get_value_bytearray())
return ret_bytes
[docs] def execute(self, simulator: M68K):
"""
Executes this command in a simulator
:param simulator: The simulator to execute the command on
:return: Nothing
"""
# get the length
val_length = self.size.get_number_of_bytes()
# get the value of src from the simulator
src_val = self.src.get_value(simulator, val_length)
# get the value of dest from the simulator
dest_val = self.dest.get_value(simulator, val_length)
# increment the program counter by the length of the instruction (1 word)
to_increment = OpSize.WORD.value
# repeat for the dest
if self.dest.mode in [EAMode.AbsoluteLongAddress]:
to_increment += OpSize.LONG.value
if self.dest.mode in [EAMode.AbsoluteWordAddress]:
to_increment += OpSize.WORD.value
# mask to apply to the source
mask = 0xFF
if self.size is OpSize.BYTE:
mask = 0xFF
if self.size is OpSize.WORD:
mask = 0xFFFF
if self.size is OpSize.LONG:
mask = 0xFFFFFFFF
# which bits of the total should not be modified
inverted_mask = 0xFFFFFFFF ^ mask
# preserve the upper bits of the operation if they aren't used
preserve = dest_val.get_value_signed() & inverted_mask
raw_total = dest_val.get_value_unsigned() - src_val.get_value_unsigned()
total = (raw_total & mask) | preserve
# If the subtraction of the masked destination and source value is
# negative, then a borrow has been generated.
borrow_bit = (mask & dest_val.get_value_unsigned()) - src_val.get_value_unsigned() < 0
negative_bit = 0
if self.size is OpSize.BYTE:
negative_bit = 0x80
elif self.size is OpSize.WORD:
negative_bit = 0x8000
elif self.size is OpSize.LONG:
negative_bit = 0x80000000
negative = total & negative_bit > 0
# Overflow occurs when a sign change occurs where it shouldn't occur.
# For example: positive - negative != negative.
# This doesn't make sense, so an overflow occurs
overflow = False
if dest_val.get_value_unsigned() & 0x80000000 > 0:
if total & negative_bit == 0:
overflow = True
# set the ccr registorio
simulator.set_ccr_reg(borrow_bit, negative, (total == 0), overflow, borrow_bit)
# and set the value
self.dest.set_value(simulator, MemoryValue(OpSize.LONG, unsigned_int=total))
# set the program counter value
simulator.increment_program_counter(to_increment)
def __str__(self):
# Makes this a bit easier to read in doctest output
return 'Subq command: Size {}, src {}, dest {}'.format(self.size, self.src, self.dest)
[docs] @classmethod
def command_matches(cls, command: str) -> bool:
"""
Checks whether a command string is an instance of this command type
:param command: The command string to check (e.g. 'MOVE.B', 'LEA', etc.)
:return: Whether the string is an instance of this command type
"""
return opcode_util.command_matches(command, 'SUB')
[docs] @classmethod
def get_word_length(cls, command: str, parameters: str) -> int:
"""
>>> Subq.get_word_length('SUBQ.B', '#5, D3')
1
>>> Subq.get_word_length('SUBQ.W', '#4, ($BBBB).W')
2
>>> Subq.get_word_length('SUBQ.L', '#7, ($BBBB).W')
2
>>> Subq.get_word_length('SUBQ.W', '#1, ($BBBB).L')
3
>>> Subq.get_word_length('SUBQ.W', '#8, ($BBBB).L')
3
>>> Subq.get_word_length('SUB.L', '#5, ($BBBB).L')
3
Gets what the end length of this command will be in memory
:param command: The text of the command itself (e.g. "LEA", "MOVE.B", etc.)
:param parameters: The parameters after the command
:return: The length of the bytes in memory in words, as well as a list of warnings or errors encountered
"""
# Split the parameters into EA modes
params = parameters.split(',')
# src = parse_assembly_parameter(params[0].strip()) # Parse the source and make sure it parsed right
dest = parse_assembly_parameter(params[1].strip())
length = 1 # Always 1 word not counting additions to end
if dest.mode == EAMode.AWA: # Appends a word
length += 1
if dest.mode == EAMode.ALA: # Appends a long, so 2 words
length += 2
return length
[docs] @classmethod
def is_valid(cls, command: str, parameters: str) -> (bool, list):
"""
Tests whether the given command is valid
>>> Subq.is_valid('SUBQ.B', '#2, D1')[0]
True
>>> Subq.is_valid('SUBQ.W', 'D0')[0]
False
>>> Subq.is_valid('SUBQ.G', '#5, D1')[0]
False
>>> Subq.is_valid('SUBQ.L', 'D0, A2')[0]
False
>>> Subq.is_valid('SU.L', '#2, D1')[0]
False
>>> Subq.is_valid('SUBQ.', '#5, D1')[0]
False
>>> Subq.is_valid('SUBQ.W', '#2, #6500')[0]
False
:param command: The command itself (e.g. 'MOVE.B', 'LEA', etc.)
:param parameters: The parameters after the command (such as the source and destination of a move)
:return: Whether the given command is valid and a list of issues/warnings encountered
"""
return opcode_util.n_param_is_valid(command, parameters, "SUBQ", 2, param_invalid_modes=[[EAMode.ARD],
[EAMode.ARD,
EAMode.IMM]])[:2]
[docs] @classmethod
def disassemble_instruction(cls, data: bytearray) -> Opcode:
"""
This has a non-subq opcode
>>> Subq.disassemble_instruction(bytearray.fromhex('0280'))
SUBQ.B #2,D7
>>> op = Subq.disassemble_instruction(bytearray.fromhex('5507'))
>>> str(op.src)
'EA Mode: EAMode.IMM, Data: 2'
>>> str(op.dest)
'EA Mode: EAMode.DRD, Data: 7'
SUBQ.W #5,D1
>>> op = Subq.disassemble_instruction(bytearray.fromhex('5B41'))
>>> str(op.src)
'EA Mode: EAMode.IMM, Data: 5'
>>> str(op.dest)
'EA Mode: EAMode.DRD, Data: 1'
SUBQ.L #7,(A0)
>>> op = Subq.disassemble_instruction(bytearray.fromhex('5F90'))
>>> str(op.src)
'EA Mode: EAMode.IMM, Data: 7'
>>> str(op.dest)
'EA Mode: EAMode.ARI, Data: 0'
SUBQ.L #3,$4000
>>> op = Subq.disassemble_instruction(bytearray.fromhex('57B84000'))
>>> str(op.src)
'EA Mode: EAMode.IMM, Data: 3'
>>> str(op.dest)
'EA Mode: EAMode.AWA, Data: 16384'
Parses some raw data into an instance of the opcode class
:param data: The data used to convert into an opcode instance
:return: The constructed instance or none if there was an error and
the amount of data in words that was used (e.g. extra for immediate
data) or 0 for not a match
"""
assert len(data) >= 2, 'Opcode size is at least one word'
first_word = int.from_bytes(data[0:2], 'big')
[opcode_bin,
data_bin,
one_bin,
size_bin,
ea_mode_binary,
ea_reg_bin] = split_bits(first_word, [4, 3, 1, 2, 3, 3])
if opcode_bin != 0b0101 or one_bin != 0b1:
return None
src = None
dest = None
size = None
# populate source data
src = AssemblyParameter(EAMode.IMM, data_bin)
# Determine size
if size_bin == 0b00:
size = OpSize.BYTE
elif size_bin == 0b01:
size = OpSize.WORD
elif size_bin == 0b10:
size = OpSize.LONG
else:
return None
# populate destination data
dest = dest = parse_ea_from_binary(ea_mode_binary, ea_reg_bin, size, False, data[2:])[0]
return cls([src, dest], size)
[docs] @classmethod
def from_str(cls, command: str, parameters: str):
"""
Parses a SUBQ command from text.
>>> str(Subq.from_str('SUBQ.B', '#4, D1'))
'Subq command: Size OpSize.BYTE, src EA Mode: EAMode.IMM, Data: 4, dest EA Mode: EAMode.DRD, Data: 1'
>>> str(Subq.from_str('SUBQ.L', '#1, (A0)'))
'Subq command: Size OpSize.LONG, src EA Mode: EAMode.IMM, Data: 1, dest EA Mode: EAMode.ARI, Data: 0'
:param command: The command itself (e.g. 'MOVE.B', 'LEA', etc.)
:param parameters: The parameters after the command (such as the source and destination of a move)
:return: The parsed command
"""
return opcode_util.n_param_from_str(command, parameters, Subq, 2, OpSize.WORD)