def check_file(opt):
    if opt.undefined_crc_parameters:
        sys.stderr.write("{0:s}: error: undefined parameters\n".format(sys.argv[0]))
        sys.exit(1)
    alg = Crc(
        width=opt.width, poly=opt.poly,
        reflect_in=opt.reflect_in, xor_in=opt.xor_in,
        reflect_out=opt.reflect_out, xor_out=opt.xor_out,
        table_idx_width=opt.tbl_idx_width)

    if not opt.reflect_in:
        register = opt.xor_in
    else:
        register = alg.reflect(opt.xor_in, opt.width)

    try:
        with open(opt.check_file, 'rb') as f:
            check_bytes = bytearray(f.read(1024))
            while check_bytes != b"":
                register = crc_file_update(alg, register, check_bytes)
                check_bytes = bytearray(f.read(1024))
    except IOError:
        sys.stderr.write(
            "{0:s}: error: can't open file {1:s}\n".format(sys.argv[0], opt.check_file))
        sys.exit(1)

    if opt.reflect_out:
        register = alg.reflect(register, opt.width)
    register = register ^ opt.xor_out
    return register


# function write_file
###############################################################################
Return mail information within a dict.
dataset/ETHPy150Open tpircher/pycrc/pycrc.py/check_file--crossover with--dataset/ETHPy150Open Gentux/imap-cli/imap_cli/fetch.py/read