How to use boost::crc?

Question

I want to use boost::crc so that it works exactly like PHP's crc32() function. I tried reading the horrible documentation and many headaches later I haven't made any progress.

Apparently I have to do something like:

int GetCrc32(const string& my_string) {
    return crc_32 = boost::crc<bits, TruncPoly, InitRem, FinalXor,
                   ReflectIn, ReflectRem>(my_string.c_str(), my_string.length());
}

bits should be 32.. What the other things are is a mystery. A little help? ;)

You can also use this http://svn.abisource.com/wv/branches/release-version-0-7-12/crc32.c and http://svn.abisource.com/wv/branches/release-version-0-7-12/crc32.h. I assume the algorithm is the same but the speed is way better than boost crc. — schoetbi, Apr 21 '11 at 12:08

score 77 · Accepted Answer · edited Oct 10 '22 at 22:15

77

Dan Story and ergosys provided good answers (apparently I was looking in the wrong place, that's why the headaches) but while I'm at it I wanted to provide a copy&paste solution for the function in my question for future googlers:

#include <boost/crc.hpp>

uint32_t GetCrc32(const string& my_string) {
    boost::crc_32_type result;
    result.process_bytes(my_string.data(), my_string.length());
    return result.checksum();
}

edited Oct 10 '22 at 22:15

parsley72

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answered Apr 04 '10 at 06:24

Andreas Bonini

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IMHO the return type should be unsigned (e.g. std::uint32_t). – Andreas Florath Aug 28 '21 at 17:23
@AndreasFlorath, I completely agree! Thanks for pointing that out. I updated the answer to use it. – Andreas Bonini Sep 15 '21 at 01:29

score 10 · Answer 2 · answered Apr 04 '10 at 06:20

You probably want to use the crc_32_type instead of using the crc template. The template is general and meant to accommodate a wide range of CRC designs using widely varying parameters, but they ship four built-in pre-configured CRC types for common usage, covering CRC16, CCITT, XMODEM and CRC32.

score 5 · Answer 3 · answered Apr 04 '10 at 06:20

5

The library includes predefined CRC engines. I think the one you want is crc_32_type. See this example: http://www.boost.org/doc/libs/1_37_0/libs/crc/crc_example.cpp

answered Apr 04 '10 at 06:20

ergosys

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score 4 · Answer 4 · answered Apr 04 '10 at 06:21

4

Have you tried using the predefined crc_32_type?

answered Apr 04 '10 at 06:21

Marcelo Cantos

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score 4 · Answer 5 · answered Apr 04 '10 at 06:22

4

On this page, find the particular 32-bit CRC you want, read off all the other parameters: http://regregex.bbcmicro.net/crc-catalogue.htm

answered Apr 04 '10 at 06:22

Ben Voigt

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How to use boost::crc?

5 Answers5