CRC32 C or C++ implementation [closed]

Answer 1

I am the author of the source code at the specified link. While the intention of the source code license is not clear (it will be later today), the code is in fact open and free for use in your free or commercial applications with no strings attached.

Answer 2

The crc code in zlib (http://zlib.net/) is among the fastest there is, and has a very liberal open source license.

And you should not use adler-32 except for special applications where speed is more important than error detection performance.

Answer 3

Use the Boost C++ libraries. There is a CRC included there and the license is good.

Answer 4

rurban's fork of SMHasher (the original SMHasher seems abandoned) has hardware CRC32 support. The changes were added before the initial commit, but try comparing the new CMakeLists.txt and the old one (which doesn't mention SSE at all).

The best option is probably Intel's zlib fork with PCLMULQDQ support described in this paper. This library also has the SSE 4.2 optimizations.

If you don't need portability and you're on Linux, you can use the kernel's implementation (which is hardware accelerated if available): https://stackoverflow.com/a/11156040/309483

Answer 5

using zlib.h (http://refspecs.linuxbase.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/zlib-crc32-1.html):

#include <zlib.h>
unsigned long  crc = crc32(0L, Z_NULL, 0);
crc = crc32(crc, (const unsigned char*)data_address, data_len);

Answer 6

The most simple and straightforward C/C++ implementation that I found is in a link at the bottom of this page:

Web Page: http://www.barrgroup.com/Embedded-Systems/How-To/CRC-Calculation-C-Code

Code Download Link: https://barrgroup.com/code/crc.zip

It is a simple standalone implementation with one .h and one .c file. There is support for CRC32, CRC16 and CRC_CCITT thru the use of a define. Also, the code lets the user change parameter settings like the CRC polynomial, initial/final XOR value, and reflection options if you so desire.

The license is not explicitly defined ala LGPL or similar. However the site does say that they are placing the code in the public domain for any use. The actual code files also say this.

Hope it helps!