Message 98308 - Python tracker

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Author	cmcqueen1975
Recipients	cmcqueen1975, dtorp, josiahcarlson, mark.dickinson, tim.peters
Date	2010-01-26.01:06:39
SpamBayes Score	0.00033885657
Marked as misclassified	No
Message-id	<1264468002.06.0.0627214993591.issue1205239@psf.upfronthosting.co.za>
In-reply-to

Content
Just for the record... here is a relevant use case... I'm working on some code for calculating CRCs, and hope to support any CRC width, including CRC-5. This involves, among the calculations: crc >> (crc_width - 8) The complete expression is: crc = table[((crc >> (crc_width - 8)) ^ data_byte) & 0xFF] ^ (crc << 8) where crc_width is typically 32 or 16, but in the case of CRC-5 would be 5. I think the calculation would work fine for all cases, if only Python allowed me to right-shift with a negative number. But now I'll have to handle the two cases separately.

Just for the record... here is a relevant use case...

I'm working on some code for calculating CRCs, and hope to support any CRC width, including CRC-5. This involves, among the calculations:

    crc >> (crc_width - 8)

The complete expression is:

    crc = table[((crc >> (crc_width - 8)) ^ data_byte) & 0xFF] ^ (crc << 8)

where crc_width is typically 32 or 16, but in the case of CRC-5 would be 5.

I think the calculation would work fine for all cases, if only Python allowed me to right-shift with a negative number. But now I'll have to handle the two cases separately.

History
Date	User	Action	Args
2010-01-26 01:06:42	cmcqueen1975	set	recipients: + cmcqueen1975, tim.peters, josiahcarlson, mark.dickinson, dtorp
2010-01-26 01:06:42	cmcqueen1975	set	messageid: <1264468002.06.0.0627214993591.issue1205239@psf.upfronthosting.co.za>
2010-01-26 01:06:40	cmcqueen1975	link	issue1205239 messages
2010-01-26 01:06:39	cmcqueen1975	create