On Tue, 16 May 2006, Alan Gauld wrote:
> Your approach is fine. Personally however I'd just have defined
> some constants and done a direct bitwise and - this is the
> approach used in the stat module:
>
> VMASK = 0x14 # 00011000
> VER00 = 0x00
> VER01 = 0x04
> VER10 = 0x10
> VER11 = 0x14
>
> version = byte & VMASK
> if version == VER00: #do something
> elif version == VER01: # do another
> etc...
Good idea. In this particular case, I actualy need the value, because
it's to be used either as a key to a dictionary or a subscript to a list
later on; i.e., my if tree would look like this:
if version == VER00:
ver_num = 0
elif version == VER01:
ver_num = 1
elif version == VER02:
ver_num = 2
elif version == VER03:
ver_num = 3
Actually, the version number doesn't equal the two-bit number; values of
0, 2 and 3 mean versions 2.5, 2 or 1, respectively (1 being reserved), but
you get the idea. The key is I need later to be able to use the value
itself.
But I have a number of other parts of the frame header where the defined
constants are a great way to go; thanks.
> But I'm just an old assembler programmer in disguise :-)
Heh, you and me both. I cut my teeth on IBM System/370 assembler. Last
time I had a job where I actually did programming as part of it, it was
System/390 machine code. That's right, machine code, not assembler; I'd
directly type my hexadecimal programs into low storage at the operator's
console.
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