link_crc.c File Reference

CRC-16, polynomial 0x1021, computed bit by bit; see link_crc.h. More...

#include "link_crc.h"

Functions
uint16_t	link_crc (uint16_t crc, const void *data, size_t len)
	Fold len bytes into crc and return the new accumulator.
uint32_t	link_fnv1a32 (uint32_t hash, const void *data, size_t len)
	FNV-1a, 32 bits: per byte, XOR then multiply by 16777619.

Detailed Description

CRC-16, polynomial 0x1021, computed bit by bit; see link_crc.h.

SPDX-License-Identifier: MIT

Function Documentation

link_crc()

uint16_t link_crc	(	uint16_t	crc,
		const void *	data,
		size_t	len )

Fold len bytes into crc and return the new accumulator.

Incremental, so a receiver can check a frame as it arrives without buffering it first.

Parameters

crc	The accumulator: LINK_CRC_INIT, or the value a previous call returned.
data	The bytes to fold in.
len	Number of bytes in data.

Returns

The new accumulator.

link_fnv1a32()

uint32_t link_fnv1a32	(	uint32_t	hash,
		const void *	data,
		size_t	len )

FNV-1a, 32 bits: per byte, XOR then multiply by 16777619.

The content key of the board drawing (LINK_AW_HASH_LO/HI) next to its CRC. Not a cryptographic hash; it tells two drawings apart, it does not authenticate one. Incremental like link_crc().

Parameters

hash	The hash: LINK_FNV_INIT, or the value a previous call returned.
data	The bytes to fold in.
len	Number of bytes in data.

Returns

The new hash.