Calculating 32 bit CRCs

From GumstixDocsWiki

When transferring files, it is sometimes desirable to verify that the file was transferred properly. One of the simplest ways of doing this is to calculate a 32-bit CRC before and after transferring the file.

Using zip & unzip

The zip and unzip utilities calculate a 32-bit CRC for each file stored in the zip archive. You can determine this CRC by doing the following:

zip test.zip somefile
unzip -lv test.zip

Using U-Boot

U-Boot has a builtin command called crc32 which will calculate over a region of memory. This is most useful after transferring a file into memory. In this scenario, a tyical invocation would look like:

crc32 a2000000 ${filesize}

Using a standalone program

You can also compile a stanalone program which will run on your host machine and/or the gumstix. Copy crc32.c and the Makefile to a directory on your build machine.

The Makefile assumes that you create a directory parallel to the gumstix-buildroot (i.e. on my system, gumstix-build root can be found at /home/dhylands/gumstix/gumstix-buildroot, so for this project I'd create /home/dhylands/gumstix/crc32). Typing make will build both the local version (called crc32) and the version which runs on the gumstix (arm-crc32).

The crc32 and arm-crc32 programs both take a single argument, the name of the file to calculate the 32-bit CRC of.