how to reading binary data...
peter at engcorp.com
Thu Oct 21 12:59:43 CEST 2004
marcos at nordesia.org wrote:
> SIGNIFICANCE = [0,1,2,3] # this list is useful when reading bigendian longs
> #SIGNIFICANCE = [3,2,1,0] # this list is useful when reading littleendian
> def str2long(s):
> """Returns a long, using the first four byte of a string"""
> l = 0L # the long we will get
> for pos in SIGNIFICANCE: # get each byte in the order specified by the
> significance list
> if pos < len(s):
> c = s[pos]
> else: # if we take a byte that is not in byte string (this happens at
> the end of file when file length is not multiple of 4.
> c = chr(0)
> l*=0x100 # shift left 8 bits
> l+=ord(c) # add the readed byte at the LSB.
> return l
Ditch this! It would be much easier, faster,
more maintainable to use the struct module:
This returns an integer from little-endian data, while
using >l assumes big-endian data.
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