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#!/usr/bin/env python3
import sys
def decode_jump(ins: int) -> str:
if (ins & 0x7) == 0:
return ""
if (ins & 0x7) == 0x7:
return "; j"
jl = (ins & (1 << 2)) != 0
je = (ins & (1 << 1)) != 0
jg = (ins & (1 << 0)) != 0
# implied: and not jg
if jl and je:
return "; jle"
# implied: and not je
if jl and jg:
return "; jne"
# implied: and not je
if je and jg:
return "; jge"
# implied: only one flag is 1
if jl:
return "; jl"
if je:
return "; je"
if jg:
return "; jg"
return "; <unknown>"
# return op, and whether it's a one-op or two-op
def decode_ins(ins: int) -> (str, bool):
opcode = (ins >> 8) & 0x03
ar_n_log = (ins & (1 << 10)) != 0
opcode |= ar_n_log << 2
if opcode == 0b000:
return "and", True
if opcode == 0b001:
return "or", True
if opcode == 0b010:
return "xor", True
if opcode == 0b011:
return "neg", False
if opcode == 0b100:
return "add", True
if opcode == 0b101:
return "inc", False
if opcode == 0b110:
return "sub", True
if opcode == 0b111:
return "dec", False
return "<?>"
# normally, X = arg1 = D
def decode_arg1(ins: int) -> str:
use_mem = (ins & (1 << 12)) != 0
zx = (ins & (1 << 7)) != 0
sw = (ins & (1 << 6)) != 0
if zx:
return "0"
if not sw:
return "D"
return "M" if use_mem else "A"
# normally, Y = arg2 = A
def decode_arg2(ins: int) -> str:
use_mem = (ins & (1 << 12)) != 0
# don't care, only X is zeroed
# zx = (ins & (1 << 7)) != 0
sw = (ins & (1 << 6)) != 0
if sw:
return "D"
return "M" if use_mem else "A"
def decode_dest(ins: int) -> str:
dA = (ins & (1 << 5)) != 0
dD = (ins & (1 << 4)) != 0
dM = (ins & (1 << 3)) != 0
dest_s = ""
if dA:
dest_s += "A "
if dD:
dest_s += "D "
if dM:
dest_s += "M"
if dest_s:
dest_s += ", "
return dest_s
def decode(ins: int) -> str:
if ins & 0x8000 == 0:
# mov? ldr? ldi? aaaaaaaaaaa....
return f"mov A, #{ins}"
else:
dest_s = decode_dest(ins)
codename, two_op = decode_ins(ins)
op1 = decode_arg1(ins)
op2 = decode_arg2(ins)
op2_s = f", {op2}" if two_op else ""
return f"{codename:<5}{dest_s:<8}{op1:<3}{op2_s:<5}{decode_jump(ins)}"
def main():
if len(sys.argv) != 2:
print(f"Usage: {sys.argv[0]} [filename]")
sys.exit(1)
try:
filename = sys.argv[1]
with open(filename, "rb") as f:
while True:
insb = f.read(2)
if not insb:
break
ins = int.from_bytes(insb)
print(f"\t{insb[0]:02x} {insb[1]:02x}\t{decode(ins)}")
except FileNotFoundError:
print(f"File {filename} not found.")
sys.exit(1)
# head, tail...
except BrokenPipeError:
sys.exit(0)
if __name__ == "__main__":
main()
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