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Consolidate all the CRC functions and LUTs in one place
Posted: Wed Oct 11, 2017 2:00 pm
by faisal
At the title says ... There are a couple CRC functions and LUTs scatter throughout the source. I think they should be in one place. I use pycrc to generate my crc library, and a little script to automate it (it renames some constants that were otherwise common). The license is permissive too (MIT). See attached.
For example, the crc in os/ex/subsystems/mfs/mfs.c, is actually crc_16ccitt. It also support arbitrary polynomial generation, so the crc7 used in os/hal/src/hal_mmc_spi.c could just as easily be generated.
Re: Consolidate all the CRC functions and LUTs in one place
Posted: Sun Oct 22, 2017 11:37 am
by Giovanni
Hi,
I am adding a crypto driver to the HAL, all such algorithms will have a place there (maybe I will add a separate one for just CRCs).
Giovanni
Re: Consolidate all the CRC functions and LUTs in one place
Posted: Sun Oct 22, 2017 2:14 pm
by steved
Giovanni wrote:maybe I will add a separate one for just CRCs
Good idea - I suspect CRCs are more commonly used than specific crypto functions.
If you envisage pre-generating LUTs for the more popular CRCs, I mostly need CCITT-16, and occasionally CRC-16. Also worth remembering the 8-bit CRCs; there's one used with the
Dallas OWB which could be handy.
Re: Consolidate all the CRC functions and LUTs in one place
Posted: Mon Oct 23, 2017 1:43 pm
by steved
Looking at the crypto interface, a separate CRC interface is definitely going to be simpler.
Three parameters usually suffice for me:
Code: Select all
uint16_t crcCCITT16(unsigned char *data, uint16_t length, uint16_t seed);
Re: Consolidate all the CRC functions and LUTs in one place
Posted: Wed Jan 17, 2018 7:41 pm
by faisal
A separate CRC directory makes more sense. The library of CRC functions I included in my first post need not (actually shouldn't ..) be part of HAL drivers. It probably deserves to be in HAL/lib. Hope we can get all those included (the one missing is crc7 whic is used in hal_mmc_spi.c. PyCRC can easily generate that as well ...).
Re: Consolidate all the CRC functions and LUTs in one place
Posted: Mon Dec 10, 2018 10:27 pm
by faisal
*Bump*
Here is an example of a script to generate a bunch of CRC functions using pyCRC and an associated makefile. Something like this could be included in hal/lib, with the pyCRC dependency in os/ext
Code: Select all
#!/bin/bash
declare -a model_names=\
(
"crc-5"
"crc-8"
"dallas-1-wire"
"crc-12-3gpp"
"crc-15"
"crc-16"
"crc-16-usb"
"crc-16-modbus"
"crc-16-genibus"
"crc-16-ccitt"
"r-crc-16"
"kermit"
"x-25"
"xmodem"
"zmodem"
"crc-24"
"crc-32"
"crc-32c"
"crc-32-mpeg"
"crc-32-bzip2"
"posix"
"jam"
"xfer"
"crc-64"
"crc-64-jones"
"crc-64-xz"
)
declare -a source_names=\
(
"crc_5"
"crc_8"
"crc_ow"
"crc_12_3g"
"crc_15"
"crc_16"
"crc_16usb"
"crc_16mb"
"crc_16gb"
"crc_16ccitt"
"crc_r16"
"crc_kmt"
"crc_x25"
"crc_xm"
"crc_zm"
"crc_24"
"crc_32"
"crc_32c"
"crc_32mpg"
"crc_32bzip2"
"crc_psx"
"crc_jam"
"crc_xfer"
"crc_64"
"crc_64jones"
"crc_64xz"
)
arr_len=${#model_names[@]}
arr_len_test=${#source_names[@]}
if [ $arr_len -ne $arr_len_test ];
then
echo "ERROR: Length mismatch between model_names and source_names."
exit 1
fi
PYCRC_PATH="./pycrc-0.9.1"
for ((i=1;i<${arr_len}+1; i++));
do
echo "Generating model: ${model_names[$i-1]}"
$PYCRC_PATH/pycrc.py --model ${model_names[$i-1]} --algorithm table-driven --generate h -o ${source_names[$i-1]}.h --symbol-prefix ${source_names[$i-1]}
$PYCRC_PATH/pycrc.py --model ${model_names[$i-1]} --algorithm table-driven --generate c -o ${source_names[$i-1]}.c --symbol-prefix ${source_names[$i-1]}
sed -i "s/CRC_ALGO_/${source_names[$i-1]^^}_ALGO_/" ${source_names[$i-1]}.h
done
# Autogenerate crc.mk
rm crc.mk
{ echo -e "\n#Generated using gen_src.sh. Do not modify manually. \n"
echo -e "CRCPATH := \$(UTILS)/crc"
echo -e "CRCSRC :="
echo -e "UTILSINC += \$(CRCPATH)/"
echo -e "CRCSRC += \\"
for srcn in "${source_names[@]::${#source_names[@]}-1}"
do
echo -e " \$(CRCPATH)/$srcn.c \\"
done
echo -e " \$(CRCPATH)/${source_names[-1]}.c"
echo
echo -e "UTILSSRC += \$(CRCSRC)"
echo
} >> crc.mk
Re: Consolidate all the CRC functions and LUTs in one place
Posted: Sat Jan 05, 2019 8:27 pm
by Giovanni
bump