[Discuss-gnuradio] CRC32 discrepancy

[ERIC BANWART]

I am using the Stream CRC32 block and was having trouble getting the CRCs to pass. After some debugging I discovered that the calculated CRC is different depending on whether or not the source data is packed. This can be observed using the attached flow graph. The result of the packed stream appears to be correct. I looked at the code for the block (crc32_impl_bb.cc) and that see that regardless of the Packed setting in the block the CRC calculated with:  d_crc_impl.process_bytes(in, packet_length);

I believe that for the unpacked case, either the bits need be repacked before the calculation or repeated calls to process_bits should be used in place of the the call to process_bytes.

My version of gnuradio is:  3.7.12git-126-g37d373ac

Thanks!

Eric

crc_test.grc
Description: crc_test.grc