newbie sending hex values over UDP socket
robmccrea at spaamadelphiaspremoveam.net
Tue Sep 14 01:58:20 CEST 2004
Bill Seitz wrote:
> Peter Hansen <peter at engcorp.com> wrote in message news:<QYGdnckJ3ukLf9zcRVn-sQ at powergate.ca>...
>>Bill Seitz wrote:
>>>Are you saying I can just do something as simple as
>>Exactly. That sends three bytes corresponding to the
>>"raw" byte values you showed before.
>>>(This interface is typically used over a modem connection between 2
>>>embedded/hardware devices, if that provides a clue/context. So it's
>>>entirely possible that I've thought the situation was more complicated
>>>than it really is because the other guy is used to dealing with these
>>The beauty of Python... makes working with even low-level hardware
>>a pleasure compared to many languages. :-)
> Excellent - now how about calculating a parity-check byte?
well, I'm new to python, but the language hardly matters here, i believe.
is the parity a bit, a few bits, or a full byte? granted the bits will
be stored in a byte, but we need to know exactly, of course. I believe
parity usually indicates a single bit (on or off), but I don't trust
I'll mention these hard-coded example, but I wouldn't be at all
surprised if python has built in bit-methods.
I number the 8 bits in a byte from 7 to 0, where 7 is the high bit.
if I wanted to check the bit number 5 in thatbyte, I would do simply,
(well, as I said, I'm new, I'm going to use extra parens)
if (thatbyte & (2**5)) == (2**5):
print 'Bit 5 is on.'
print 'Bit 5 is off.'
for more than one bit, say the "first" 3 bits: 7, 6, and 5:
for bit in [7, 6, 5]:
if (thatbyte & (2**bit)) == (2**bit):
print 'Bit ' + str(bit) + 'is on.'
print 'Bit ' + str(bit) + 'is off.'
Its bit math.
I think those're right. hope so.
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