On 8/10/04 11:32 AM, "Bert Klaps" <bertk@txc.com> wrote:
I ran into a problem using the CRC library for SDH LCAS control words (3-bit CRC) and SDH Trail Trace Identifier messages (7-bit CRC).
Could you provide sample data and answer so a new test case can be added?
For CRC widths smaller than character width the theoretical and optimized CRC computers produce different results for non-reflected input. Gcc produces this warning:
/usr/local/boost/boost_1_31_0/boost/crc.hpp:581: warning: right shift count >= width of type
The problem is that for the table based computer the msb of the remainder needs to be compared to the msb of the input byte. For most popular CRC parameters that's a right shift, but for CRC widths smaller than a character this should be a left shift...
Reflected input requires comparing lsb's which doesn't involve any shifting.
I've attached a patch that solved the problem for me. [TRUNCATED list of errors and the patch]
Does anyone know how to add patches to a file? (It looked like it was in a "diff" format. Isn't there an automated tool for this, or do I apply the changes manually?) Have we branched for release yet? I don't want to add the changes (to the main line) until then so I won't risk breaking the release build. -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com