Functions
uint16_t	crc16 (uint16_t poly, uint16_t seed, const uint8_t *src, size_t len)
	Generic function for computing a CRC-16 without input or output reflection. More...

uint16_t	crc16_reflect (uint16_t poly, uint16_t seed, const uint8_t *src, size_t len)
	Generic function for computing a CRC-16 with input and output reflection. More...

uint8_t	crc8 (const uint8_t *src, size_t len, uint8_t polynomial, uint8_t initial_value, bool reversed)
	Generic function for computing CRC 8. More...

uint16_t	crc16_ccitt (uint16_t seed, const uint8_t *src, size_t len)
	Compute the checksum of a buffer with polynomial 0x1021, reflecting input and output. More...

uint16_t	crc16_itu_t (uint16_t seed, const uint8_t *src, size_t len)
	Compute the checksum of a buffer with polynomial 0x1021, no reflection of input or output. More...

static uint16_t	crc16_ansi (const uint8_t *src, size_t len)
	Compute the ANSI (or Modbus) variant of CRC-16. More...

uint32_t	crc32_ieee (const uint8_t *data, size_t len)
	Generate IEEE conform CRC32 checksum. More...

uint32_t	crc32_ieee_update (uint32_t crc, const uint8_t *data, size_t len)
	Update an IEEE conforming CRC32 checksum. More...

uint32_t	crc32_c (uint32_t crc, const uint8_t *data, size_t len, bool first_pkt, bool last_pkt)
	Calculate CRC32C (Castagnoli) checksum. More...

uint8_t	crc8_ccitt (uint8_t initial_value, const void *buf, size_t len)
	Compute CCITT variant of CRC 8. More...

uint8_t	crc7_be (uint8_t seed, const uint8_t *src, size_t len)
	Compute the CRC-7 checksum of a buffer. More...

Detailed Description

Function Documentation

◆ crc16()

uint16_t crc16	(	uint16_t	poly,
		uint16_t	seed,
		const uint8_t *	src,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Generic function for computing a CRC-16 without input or output reflection.

Compute CRC-16 by passing in the address of the input, the input length and polynomial used in addition to the initial value. This is O(n*8) where n is the length of the buffer provided. No reflection is performed.

Note: If you are planning to use a CRC based on poly 0x1012 the functions crc16_itu_t() is faster and thus recommended over this one.

Parameters

poly	The polynomial to use omitting the leading x^16 coefficient
seed	Initial value for the CRC computation
src	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC16 value (without any XOR applied to it)

◆ crc16_ansi()

static uint16_t crc16_ansi	(	const uint8_t *	src,
		size_t	len
	)

inlinestatic

#include <include/zephyr/sys/crc.h>

Compute the ANSI (or Modbus) variant of CRC-16.

The ANSI variant of CRC-16 uses 0x8005 (0xA001 reflected) as its polynomial with the initial * value set to 0xffff.

Parameters

src	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC16 value

◆ crc16_ccitt()

uint16_t crc16_ccitt	(	uint16_t	seed,
		const uint8_t *	src,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Compute the checksum of a buffer with polynomial 0x1021, reflecting input and output.

This function is able to calculate any CRC that uses 0x1021 as it polynomial and requires reflecting both the input and the output. It is a fast variant that runs in O(n) time, where n is the length of the input buffer.

The following checksums can, among others, be calculated by this function, depending on the value provided for the initial seed and the value the final calculated CRC is XORed with:

CRC-16/CCITT, CRC-16/CCITT-TRUE, CRC-16/KERMIT https://reveng.sourceforge.io/crc-catalogue/16.htm#crc.cat.crc-16-kermit initial seed: 0x0000, xor output: 0x0000
CRC-16/X-25, CRC-16/IBM-SDLC, CRC-16/ISO-HDLC https://reveng.sourceforge.io/crc-catalogue/16.htm#crc.cat.crc-16-ibm-sdlc initial seed: 0xffff, xor output: 0xffff

Note: To calculate the CRC across non-contiguous blocks use the return value from block N-1 as the seed for block N.

See ITU-T Recommendation V.41 (November 1988).

Parameters

seed	Value to seed the CRC with
src	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC16 value (without any XOR applied to it)

◆ crc16_itu_t()

uint16_t crc16_itu_t	(	uint16_t	seed,
		const uint8_t *	src,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Compute the checksum of a buffer with polynomial 0x1021, no reflection of input or output.

This function is able to calculate any CRC that uses 0x1021 as it polynomial and requires no reflection on both the input and the output. It is a fast variant that runs in O(n) time, where n is the length of the input buffer.

The following checksums can, among others, be calculated by this function, depending on the value provided for the initial seed and the value the final calculated CRC is XORed with:

CRC-16/XMODEM, CRC-16/ACORN, CRC-16/LTE https://reveng.sourceforge.io/crc-catalogue/16.htm#crc.cat.crc-16-xmodem initial seed: 0x0000, xor output: 0x0000
CRC16/CCITT-FALSE, CRC-16/IBM-3740, CRC-16/AUTOSAR https://reveng.sourceforge.io/crc-catalogue/16.htm#crc.cat.crc-16-ibm-3740 initial seed: 0xffff, xor output: 0x0000
CRC-16/GSM https://reveng.sourceforge.io/crc-catalogue/16.htm#crc.cat.crc-16-gsm initial seed: 0x0000, xor output: 0xffff

Note: To calculate the CRC across non-contiguous blocks use the return value from block N-1 as the seed for block N.

See ITU-T Recommendation V.41 (November 1988) (MSB first).

Parameters

seed	Value to seed the CRC with
src	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC16 value (without any XOR applied to it)

◆ crc16_reflect()

uint16_t crc16_reflect	(	uint16_t	poly,
		uint16_t	seed,
		const uint8_t *	src,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Generic function for computing a CRC-16 with input and output reflection.

Compute CRC-16 by passing in the address of the input, the input length and polynomial used in addition to the initial value. This is O(n*8) where n is the length of the buffer provided. Both input and output are reflected.

Note: If you are planning to use a CRC based on poly 0x1012 the function crc16_ccitt() is faster and thus recommended over this one.

The following checksums can, among others, be calculated by this function, depending on the value provided for the initial seed and the value the final calculated CRC is XORed with:

CRC-16/ANSI, CRC-16/MODBUS, CRC-16/USB, CRC-16/IBM https://reveng.sourceforge.io/crc-catalogue/16.htm#crc.cat.crc-16-modbus poly: 0x8005 (0xA001) initial seed: 0xffff, xor output: 0x0000

Parameters

poly	The polynomial to use omitting the leading x^16 coefficient. Important: please reflect the poly. For example, use 0xA001 instead of 0x8005 for CRC-16-MODBUS.
seed	Initial value for the CRC computation
src	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC16 value (without any XOR applied to it)

◆ crc32_c()

uint32_t crc32_c	(	uint32_t	crc,
		const uint8_t *	data,
		size_t	len,
		bool	first_pkt,
		bool	last_pkt
	)

#include <include/zephyr/sys/crc.h>

Calculate CRC32C (Castagnoli) checksum.

Parameters

crc	CRC32C checksum that needs to be updated.
*data	Pointer to data on which the CRC should be calculated.
len	Data length.
first_pkt	Whether this is the first packet in the stream.
last_pkt	Whether this is the last packet in the stream.

Returns: CRC32 value.

◆ crc32_ieee()

uint32_t crc32_ieee	(	const uint8_t *	data,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Generate IEEE conform CRC32 checksum.

Parameters

*data	Pointer to data on which the CRC should be calculated.
len	Data length.

Returns: CRC32 value.

◆ crc32_ieee_update()

uint32_t crc32_ieee_update	(	uint32_t	crc,
		const uint8_t *	data,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Update an IEEE conforming CRC32 checksum.

Parameters

crc	CRC32 checksum that needs to be updated.
*data	Pointer to data on which the CRC should be calculated.
len	Data length.

Returns: CRC32 value.

◆ crc7_be()

uint8_t crc7_be	(	uint8_t	seed,
		const uint8_t *	src,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Compute the CRC-7 checksum of a buffer.

See JESD84-A441. Used by the MMC protocol. Uses 0x09 as the polynomial with no reflection. The CRC is left justified, so bit 7 of the result is bit 6 of the CRC.

Parameters

seed	Value to seed the CRC with
src	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC7 value

◆ crc8()

uint8_t crc8	(	const uint8_t *	src,
		size_t	len,
		uint8_t	polynomial,
		uint8_t	initial_value,
		bool	reversed
	)

#include <include/zephyr/sys/crc.h>

Generic function for computing CRC 8.

Compute CRC 8 by passing in the address of the input, the input length and polynomial used in addition to the initial value.

Parameters

src	Input bytes for the computation
len	Length of the input in bytes
polynomial	The polynomial to use omitting the leading x^8 coefficient
initial_value	Initial value for the CRC computation
reversed	Should we use reflected/reversed values or not

Returns: The computed CRC8 value

◆ crc8_ccitt()

uint8_t crc8_ccitt	(	uint8_t	initial_value,
		const void *	buf,
		size_t	len
	)

#include <include/zephyr/sys/crc.h>

Compute CCITT variant of CRC 8.

Normal CCITT variant of CRC 8 is using 0x07.

Parameters

initial_value	Initial value for the CRC computation
buf	Input bytes for the computation
len	Length of the input in bytes

Returns: The computed CRC8 value

Functions

Detailed Description

Function Documentation

◆ crc16()

◆ crc16_ansi()

◆ crc16_ccitt()

◆ crc16_itu_t()

◆ crc16_reflect()

◆ crc32_c()

◆ crc32_ieee()

◆ crc32_ieee_update()

◆ crc7_be()

◆ crc8()

◆ crc8_ccitt()