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#!/usr/bin/env python3
import sys
if len(sys.argv) != 2:
print(f"Usage: {sys.argv[0]} [filename]")
sys.exit(1)
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"
# and not sw?
# zx and swap: don't care, other arg is zeroed
if not zx and not sw and not use_mem: return "A"
if not zx and not sw and use_mem: return "M"
return "?"
# normally, Y = arg2 = A
def decode_arg2(ins: int) -> str:
use_mem = (ins & (1<<12)) != 0
zx = (ins & (1<<7)) != 0
sw = (ins & (1<<6)) != 0
if zx and sw: return "0"
# zx and not swap: don't care, other arg is zeroed
# zx ???
if sw and not use_mem: return "A"
if sw and use_mem: return "M"
return "?"
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():
try:
with open(sys.argv[1], "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 not found.")
sys.exit(1)
# head, tail...
except BrokenPipeError:
sys.exit(0)
if __name__ == "__main__":
main()
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