119a120,159
> POLY64REVh = 0xd8000000L
> CRCTableh = [0] * 256
> CRCTablel = [0] * 256
> isInitialized = False
> 
> def CRC64(seq):
>     """ given a nucleotide or amino-acid secuence (or any string),
>         returns the CRC64 checksum. CRC64 is used by UNIPROT, EMBL and NCBI
>         as a checksum algorithm.
>         Adapted by Sebastian Bassi (sbassi AT genesdigitales.com) from
>         gian paolo ciceri code (Python Cookbook Receipe 259177) """
>     global isInitialized
>     crcl = 0
>     crch = 0
>     if (isInitialized is not True):
>         isInitialized = True
>         for i in xrange(256): 
>             partl = i
>             parth = 0L
>             for j in xrange(8):
>                 rflag = partl & 1L                
>                 partl >>= 1L               
>                 if (parth & 1):
>                     partl |= (1L << 31L)
>                 parth >>= 1L
>                 if rflag:
> 	                parth ^= POLY64REVh
>             CRCTableh[i] = parth;
>             CRCTablel[i] = partl;
> 
>     for item in seq:
>         shr = 0L
>         shr = (crch & 0xFF) << 24
>         temp1h = crch >> 8L
>         temp1l = (crcl >> 8L) | shr                        
>         tableindex = (crcl ^ ord(item)) & 0xFF
>         
>         crch = temp1h ^ CRCTableh[tableindex]
>         crcl = temp1l ^ CRCTablel[tableindex]
>     return "%08X%08X" % (crch, crcl)