README.md

crc32c v1.2

This is an amalgamation of Mark Adler's hardware-accelerated C-language implementation of the CRC-32C (Castagnoli) algorithm as found on Stack Overflow, additional code of his, and some other bits and bobs created by me (Dan Cassidy), all in order to create a crc32c binary that could be easily compiled.

None of the C code was developed by me. I simply collected the disparate parts, tweaked things ever so slightly, added a few complimentary files, and stuck the resultant bits in a git repo.

Compiling

NOTE: Requires make and gcc.

Run make.

Installing

Run sudo make install to install the crc32c binary to "/usr/local/bin" (compiling it first, if necessary).

Alternatively, you can just manually copy the binary to wherever you need it.

Usage

crc32c [[-]nnn] < data will checksum anything passed in via the stdin stream nnn times (defaults to 1), preferably using the hardware implementation. If nnn is negative, the software implementation is forced.

• echo "foo" > foo.txt; crc32c < foo.txt: 9626347b
• crc32c <<< "text to checksum": c748368b
• echo "more text to checksum" | crc32c: bc55db06

File Origins

• .gitignore: Created for this repo
• Makefile: Created for this repo
• README.md: Created for this repo
• crc32c.c: https://stackoverflow.com/a/17646775 (first code block), retrieved 2023-06-22
  • the TEST macro is a graft onto the end of this file and comes from https://github.com/madler/brotli/blob/46ecea69a993a7ebd2de4a60ae6042d31e26213f/crc32c.c#L426-L472, retrieved 2023-06-22
  • NOTE: The TEST macro is altered to remove the preceding 0x from the checksum when printed to keep the resulting binary's behavior consistent with that of other checksum-generating tools.
• generate_crc32c_h.c: https://stackoverflow.com/a/17646775 (second code block), retrieved 2023-06-22
• load.c: https://github.com/madler/brotli/blob/46ecea69a993a7ebd2de4a60ae6042d31e26213f/load.c, retrieved 2023-06-22
• load.h: https://github.com/madler/brotli/blob/46ecea69a993a7ebd2de4a60ae6042d31e26213f/load.h, retrieved 2023-06-22

Licenses

• .gitignore: MIT, Copyright 2023 Dan Cassidy
• Makefile: MIT, Copyright 2023 Dan Cassidy
• README.md: MIT, Copyright 2023 Dan Cassidy
• crc32c.c: CC BY-SA 4.0, via the Stack Exchange Terms of Service as detailed here and here
  • The TEST macro is Apache 2.0, via the license in its origin repo
• generate_crc32c_h.c: CC BY-SA 4.0, via the Stack Exchange Terms of Service as detailed here and here
• load.c: Apache 2.0, via the license in its origin repo
• load.h: Apache 2.0, via the license in its origin repo