Message98394
| Author |
cmcqueen1975 |
| Recipients |
cmcqueen1975, dtorp, josiahcarlson, mark.dickinson, tim.peters |
| Date |
2010年01月27日.00:38:45 |
| SpamBayes Score |
5.0492734e-05 |
| Marked as misclassified |
No |
| Message-id |
<1264552727.16.0.225292370736.issue1205239@psf.upfronthosting.co.za> |
| In-reply-to |
| Content |
Thanks, good points. I'm thinking with a C background and the fixed-width data types. The 0xFF could be needed if the data_byte is actually a larger number and you need to ensure only the lowest 8 bits are set. Or, if there is some sign-extending going on with the right-shift. That could happen in Python if the user passed a negative 'crc' in to the function (for whatever reason).
Yes, I'm missing a final mask. Thanks for pointing that out. I was thinking like a C programmer!
As for crc << 8 >> crc_width... the 'crc << 8' could bump an integer into long territory, making calculations slower. E.g.:
>>> 2**23 << 8 >> 16
32768L
>>> 2**23 >> (16 - 8)
32768 |
|