Extract data from ASCII file

[Anton Vredegoor]

eley_greg at bah.com (eleyg) wrote:

>> :10000000E7280530AC00A530AD00AD0B0528AC0BE2
>> 
>> The data I want to extract are 8 hexadecimal strings, the first of
>> which is E728, like this:
>> 
>> :10000000 E728 0530 AC00 A530 AD00 AD0B 0528 AC0B E2
>> 
>> Also, the bytes in the string are reversed. The E728 needs to be 28E7,
>> 0530 needs to be 3005 and so on.
>
>The first response only works with python-2.3 (yield is a newly
>reserved word).
>
>The second response did not work for me and left off the last couple
>values.

The third response uses typechecking and stores a value in an
unreachable place ...

Maybe the feachur-less code is better (tested very lightly):

def asBytes(line,offset):
    """ split a line into 2-char chunks, starting at offset'"""
    res = []
    for i in range(offset,len(line),2):
        res.append(line[i:i+2])
    return res

def asWords(line,offset=0,swapbytes=0):
    """split a line into words that have maximally 4 chars,
        starting at offset, optionally swapping 2-char chunks"""
    res = []
    flip = 0
    for b in asBytes(line,offset):
        if flip: 
            if swapbytes:
                res.append(b+prev)
            else:
                res.append(prev+b)                
        else: 
            prev = b
        flip = 1-flip
    if flip: 
        res.append(b)
    return res

def test():
    line =":10000000E7280530AC00A530AD00AD0B0528AC0BE2"
    print asWords(line,offset=9,swapbytes=1)

if __name__=='__main__':
    test()

output is:

['28E7', '3005', '00AC', '30A5', '00AD', '0BAD', '2805', '0BAC', 'E2']

Anton