file2codegrp.py

import bitstring
import sys
import os

def printusage():
    print('Usage: file2codegrp.py infile [outfile]')
    exit()

def str_base(number, base):
    (d,m) = divmod(number,len(base))
    if d > 0:
        return str_base(d,base)+base[m]
    return base[m]

#bitstring.BitArray(uie=1322)

bs = bitstring.BitArray()
lastchar = 0
s = []

def putchar(c):
    global s
    s += c
    if len(s) >= 5:
        f2.write(' '.join(s[:5])+'. ')
        del s[:5]

def putbytes(b):
    global lastchar
    bs.append(b)
    while len(bs) >= 19:
        code = bs[:19].uint
        del bs[:19]
        code = str_base(code, [[0], [1], [2], [3], [4], [5], [6], [7], [8]])
        if len(code) < 6:
            code = [0] * (6 - len(code)) + code
        for i in range(len(code)):
            code[i] = (lastchar + code[i] + 1) % 10
            lastchar = code[i]
            putchar([chr(lastchar+48)])

if len(sys.argv) < 2:
    printusage()
infile_name = sys.argv[1]
if len(sys.argv) > 2:
    outfile_name = sys.argv[2]
else:
    outfile_name = infile_name + '.txt'
try:
    f1 = open(infile_name, 'rb')
except:
    print('Error opening infile')
    print("Unexpected error:", sys.exc_info()[0])
    printusage()
try:
    f2 = open(outfile_name, 'w')
except:
    print('Error opening outfile')
    print("Unexpected error:", sys.exc_info()[0])
    printusage()
fn = os.path.basename(infile_name).encode('utf-8')
bs.append(bitstring.Bits(uie=len(fn)))
bs.append(fn)
bs.append(bitstring.Bits(uie=os.stat(infile_name).st_size))
buf = f1.read(512)
while len(buf) > 0:
    putbytes(buf)
    buf = f1.read(512)
f1.close()
putbytes(b'\0' * (((19 - len(bs)) % 19 + 7) // 8))
putchar('0' * ((5 - len(s)) % 5))
f2.close()