Processing BCD and Signed Integer Fields with Python

[Carey Evans]

"Chris Lada" <chris.lada at westgroup.com> writes:

>  Being a newbie in python, I have to ask these questions: what functions can
> I use to process these fields ?  What can I use to separate the number from
> the sign ?   Is there a conversion for this type of data to strings ? What
> data types would they be ?

Here's some code that works with the kind of data I can get from our
IBM AS/400.  It could probably be more efficient, and your mainframe
might not be generating the same data formats, but it should give you
the right idea.

For example:

>>> packed2num('\x12\x34\x5f')
12345L
>>> zoned2num('\xf1\xf2\xd3')
-123L

--------------------
import array

def zoned2num(z):
    a = array.array('B', z)
    v = 0L

    for i in a:
        v = (v * 10) + (i & 0xf)

    if (a[-1] & 0xf0) == 0xd0:
        v = -v

    return v

def packed2num(p):
    a = array.array('B', p)
    v = 0L

    for i in a[:-1]:
        v = (v * 100) + (((i & 0xf0) >> 4) * 10) + (i & 0xf)

    i = a[-1]
    v = (v * 10) + ((i & 0xf0) >> 4)
    if (i & 0xf) == 0xd:
        v = -v

    return v
--------------------

-- 
	 Carey Evans  http://home.clear.net.nz/pages/c.evans/

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