codegrp2file.py

import bitstring
import sys
import os

def printusage():
    print('Usage: codegrp2file.py infile')
    exit()

bs = bitstring.BitStream()
lastchar = 0
digpos = 0
block = 0
s = ''

def processline(s):
    global block
    global lastchar
    global digpos
    global bs
    for i in range(len(s)):
        if s[i] in '0123456789':
            block = block * 9 + (ord(s[i]) - 49 - lastchar) % 10
            lastchar = ord(s[i]) - 48
            digpos += 1
            if digpos == 6:
                digpos = 0
                tbs = bitstring.Bits(uint=block, length=19)
                bs.append(tbs)
                block = 0


if len(sys.argv) < 2:
    printusage()
infile_name = sys.argv[1]
try:
    f1 = open(infile_name, 'r')
except:
    print('Error opening infile')
    print("Unexpected error:", sys.exc_info()[0])
    printusage()
s = f1.read(512)
if len(s)==0:
    print('Unexpected EOF')
    exit()
processline(s)
print(bs)
failed = True
while failed:
    try:
        fnlen = bs.read('uie')
        print('fnlen=',fnlen)
        failed = False
    except:
        failed = True
        s = f1.read(512)
        if len(s)==0:
            print('Unexpected EOF')
            exit()
        processline(s)
del bs[:bs.pos]
bs.pos = 0
failed = True
while failed:
    try:
        fn = bs.read('bytes:'+str(fnlen))
        print('fn=',fn)
        failed = False
    except:
        failed = True
        s = f1.read(512)
        if len(s)==0:
            print('Unexpected EOF')
            exit()
        processline(s)
del bs[:bs.pos]
bs.pos = 0
outfile_name = fn.decode('utf-8')
try:
    f2 = open(outfile_name, 'wb')
except:
    print('Error opening outfile')
    print("Unexpected error:", sys.exc_info()[0])
    printusage()
failed = True
while failed:
    try:
        flen = bs.read('uie')
        print('flen=',flen)
        failed = False
    except:
        failed = True
        s = f1.read(512)
        if len(s)==0:
            print('Unexpected EOF')
            exit()
        processline(s)
del bs[:bs.pos]
bs.pos = 0
for i in range(flen):
    failed = True
    while failed:
        try:
            nb = bs.read('bytes:1')
            failed = False
        except:
            failed = True
            s = f1.read(512)
            if len(s)==0:
                print('Unexpected EOF')
                exit()
            processline(s)
    del bs[:bs.pos]
    bs.pos = 0
    f2.write(nb)

f1.close()
f2.close()