import os
import sys
import struct

argc = len(sys.argv)

if argc != 3:
    script = os.path.basename(__file__)
    sys.exit("usage: {} <filename> <value>".format(script))


filename = sys.argv[1]
value = int(sys.argv[2], 0)

if value < 0 or value > 0xff:
    sys.exit("value must be in the range [0, 0xff]")

with open(filename, "r+b") as file:

    # Determine the size of the file
    file.seek(0, os.SEEK_END)
    size = file.tell()

    address = 0
    while address < size:

        # Read the next byte
        file.seek(address)
        byte = struct.unpack("B", file.read(1))[0]

        # Check for a match
        if byte == value:
            print hex(address)

        address += 1