CPP/CRC

A very small, fast, header-only, C++ library for generating CRCs

Requirements

• C++14 or greater

Features

• Can be used to generate arbitrary/custom CRC calculators, and CRC lookup tables at compile time
• Header-only, single file, very small backend implementation (<100 lines)
• Very fast check out the benchmarks
• Each CRC function has the signature:

constexpr out_t crc_type::crc_name::calc(
    const uint8_t *bytes, size_t num_bytes, out_t prior_crc_value = null_crc)

• Support for the following algorithms are built-in:
  • CRC8::CRC8::calc
  • CRC8::CDMA2000::calc
  • CRC8::DARC::calc
  • CRC8::DVB_S2::calc
  • CRC8::EBU::calc
  • CRC8::I_CODE::calc
  • CRC8::ITU::calc
  • CRC8::MAXIM::calc
  • CRC8::ROHC::calc
  • CRC8::WCDMA::calc
  • CRC16::ARC::calc
  • CRC16::AUG_CCITT::calc
  • CRC16::BUYPASS::calc
  • CRC16::CCITT_FALSE::calc
  • CRC16::CDMA2000::calc
  • CRC16::DDS_110::calc
  • CRC16::DECT_R::calc
  • CRC16::DECT_X::calc
  • CRC16::DNP::calc
  • CRC16::EN_13757::calc
  • CRC16::GENIBUS::calc
  • CRC16::KERMIT::calc
  • CRC16::MAXIM::calc
  • CRC16::MCRF4XX::calc
  • CRC16::MODBUS::calc
  • CRC16::RIELLO::calc
  • CRC16::T10_DIF::calc
  • CRC16::TELEDISK::calc
  • CRC16::TMS37157::calc
  • CRC16::USB::calc
  • CRC16::X_25::calc
  • CRC16::XMODEM::calc
  • CRC16::A::calc
  • CRC32::CRC32::calc
  • CRC32::BZIP2::calc
  • CRC32::JAMCRC::calc
  • CRC32::MPEG_2::calc
  • CRC32::POSIX::calc
  • CRC32::SATA::calc
  • CRC32::XFER::calc
  • CRC32::C::calc
  • CRC32::D::calc
  • CRC32::Q::calc
  • CRC64::ECMA::calc
  • CRC64::GO_ISO::calc
  • CRC64::WE::calc
  • CRC64::XY::calc

Usage Examples

Using the built-in CRC functions

// 1) include "cppcrc.h"
#include "cppcrc.h"
#include <stdio.h>

// 2) use the CRC8/CRC16/CRC32 functions, for example:
int main()
{
    uint8_t data[] = {0x12, 0x5A, 0x23, 0x19, 0x92, 0xF3, 0xDE, 0xC2, 0x5A, 0x1F, 0x91, 0xA3};

    // calculate a checksum:
    uint16_t crc_value = CRC16::CCITT_FALSE::calc(data, sizeof(data));
    printf("crc_value = 0x%04X\n", crc_value);

    // view the lookup table:
    auto &crc_table = CRC16::CCITT_FALSE::table();
    printf("crc_table = {0x%04X", crc_table[0]);
    for (int i = 1; i < 256; i++)
        printf(", 0x%04X", crc_table[i]);
    printf("}\n");
}

Creating Your Own CRC Function

// 1) include "cppcrc.h"
#include "cppcrc.h"
#include <stdio.h>

int main()
{
    // 2) pick some CRC settings (these are just an example)
    using base_type = uint8_t;
    constexpr base_type poly = 0x12;
    constexpr base_type init_value = 0x34;
    constexpr bool reflect_in = true;
    constexpr bool reflect_out = true;
    constexpr base_type Xor_out = 0xFF;

    // 3) create a new CRC type by filling in the CRC parameters
    using your_crc_name = crc_utils::crc<base_type, poly, init_value, reflect_in, reflect_out, Xor_out>;

    // you can use your new CRC type to calculate a checksum
    uint8_t data[] = {0x12, 0x34, 0x56};
    auto calculated_crc = your_crc_name::calc(data, sizeof(data));
    printf("calculated_crc = 0x%02X\n", calculated_crc);

    // and even continue an existing calculation
    uint8_t more_data[] = {0x78, 0x9A};
    calculated_crc = your_crc_name::calc(more_data, sizeof(more_data),  calculated_crc);
    printf("calculated_crc = 0x%02X\n", calculated_crc);

    // and access the underlying lookup table for your CRC function
    auto &crc_table = your_crc_name::table();
}

Benchmarks

Using data generated at run-time with various array sizes and checksum algorithms

ns/64kB	64kB/s	err%	ins/64kB	bra/64kB	miss%	total	Checkum Calculators
118,718.50	8,423.29	0.5%	527,620.00	65,943.00	0.0%	1.20	DarrenLevine/cppcrc
118,729.00	8,422.54	0.5%	577,143.00	65,959.00	0.0%	1.20	boostorg/crc
122,306.00	8,176.21	0.5%	560,697.00	65,987.00	0.0%	1.23	d-bahr/CRCpp [w/ static table]
151,351.00	6,607.16	0.5%	890,311.00	65,943.00	0.0%	1.53	pstolarz/CRaC
380,683.00	2,626.86	1.2%	3,083,889.00	115,556.00	5.3%	3.83	d-bahr/CRCpp

Using data generated at compile-time with various array sizes and checksum algorithms

ns/64kB	64kB/s	err%	ins/64kB	bra/64kB	miss%	total	Checkum Calculators
0.45	2,229,858,535.96	0.5%	1.00	0.00	0.0%	0.22	DarrenLevine/cppcrc [w/ constexpr data]
0.45	2,219,406,249.99	0.5%	1.00	0.00	0.0%	0.22	pstolarz/CRaC [w/ constexpr data]
995.09	1,004,933.31	0.5%	5,805.27	643.95	0.2%	0.22	boostorg/crc [w/ constexpr data]
1,014.95	985,270.21	0.4%	5,716.24	667.95	0.2%	0.22	d-bahr/CRCpp [w/ constexpr data]

Benchmarked using nanobench on a AMD Ryzen 9 5900HS CPU. See benchmark/main.cpp for exact details.

How to run the benchmarks (it's recommended you install boost first):

git clone https://github.com/DarrenLevine/cppcrc.git
cd cppcrc/benchmark && make