.. _crc:

CRC

Overview

The CRC subsystem provides software implementations of various Cyclic Redundancy Check algorithms for data integrity verification. CRCs are commonly used to detect accidental changes to data in storage and communication systems.

The subsystem offers a comprehensive set of CRC algorithms including CRC-4, CRC-7, CRC-8, CRC-16, CRC-24, and CRC-32 variants, and provides optional hardware acceleration support when available.

.. note:: This library is distinct from the :ref:CRC hardware driver API <crc_api>, which provides an interface to hardware CRC acceleration peripherals.

When a hardware CRC unit is available and the zephyr,crc property has been set in the /chosen node in Devicetree, the library functions will default to using hardware acceleration for improved performance (can be disabled by setting :kconfig:option:CONFIG_CRC_HW_HANDLER to n).

Usage

To compute a CRC, include the appropriate header and call the desired function:

.. code-block:: c

#include <zephyr/sys/crc.h>

uint8_t data[] = {0x01, 0x02, 0x03, 0x04}; uint32_t checksum = crc32_ieee(data, sizeof(data));

For streaming data processed in chunks, use the "update" variants:

.. code-block:: c

uint32_t crc = 0; crc = crc32_ieee_update(crc, chunk1, len1); crc = crc32_ieee_update(crc, chunk2, len2); /* Final CRC value is in 'crc' */

The generic :c:func:crc_by_type function provides a unified interface to select the CRC algorithm at runtime.

Configuration

Related configuration options:

:kconfig:option:CONFIG_CRC - Enable CRC support
:kconfig:option:CONFIG_CRC_HW_HANDLER - Enable hardware CRC acceleration
:kconfig:option:CONFIG_CRC_SHELL - Enable CRC shell commands
:kconfig:option-regex:CONFIG_CRC[0-9].* - Enable software implementations of specific CRC algorithms

API Reference

.. doxygengroup:: crc