wehub-resource-sync
123 lines
4.3 KiB
C
123 lines
4.3 KiB
C
/*
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* SPDX-FileCopyrightText: 2010-2026 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#pragma once
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdint.h>
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/** Notes about CRC API
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* The ROM CRC helpers accelerate CRC-8, CRC-16, and CRC-32 calculations for
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* the following base polynomials:
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* CRC-8 x8+x2+x1+1 0x07
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* CRC16-CCITT x16+x12+x5+1 0x1021
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* CRC32 x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x1+1 0x04c11db7
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*
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* The `_le` and `_be` suffixes describe the bit processing order:
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* - use the little-endian helper when `refin == true` and `refout == true`
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* - use the big-endian helper when `refin == false` and `refout == false`
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*
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* These helpers invert the CRC register before and after processing each call.
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* As a result:
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* - the first call must receive the bitwise inverse of the CRC variant's
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* initial value
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* - each later call must receive the previous helper's return value so
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* non-contiguous buffers can be chained
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* - the final CRC value must be bitwise inverted again before applying the
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* CRC variant's `xorout`
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*
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* The initial value and final XOR depend on the CRC flavor that you are
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* implementing, so these helpers do not define a single universal
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* INITIAL/FINAL_XOR pair.
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*
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* Example for a CRC-32 flavor with `init = 0xffffffff`, `refin = true`,
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* `refout = true`, `xorout = 0xffffffff`:
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* uint32_t crc = (uint32_t)~0xffffffff;
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* crc = crc32_le(crc, buf0, length0);
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* crc = crc32_le(crc, buf1, length1);
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* crc = ~crc ^ 0xffffffff;
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*
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* Example for CRC-16/XMODEM with `init = 0x0000`, `refin = false`,
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* `refout = false`, `xorout = 0x0000`:
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* uint16_t crc = (uint16_t)~0x0000;
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* crc = crc16_be(crc, buf0, length0);
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* crc = crc16_be(crc, buf1, length1);
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* crc = (uint16_t)(~crc ^ 0x0000);
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*/
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/**
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* @brief CRC32 value in little endian.
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*
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* @param crc: Bitwise inverse of the CRC variant's initial value on the first
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* call, or the previous return value to continue a calculation
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* @param buf: Data buffer that used to calculate the CRC value
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* @param len: Length of the data buffer
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* @return CRC32 value
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*/
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uint32_t esp_rom_crc32_le(uint32_t crc, uint8_t const *buf, uint32_t len);
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/**
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* @brief CRC32 value in big endian.
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*
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* @param crc: Bitwise inverse of the CRC variant's initial value on the first
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* call, or the previous return value to continue a calculation
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* @param buf: Data buffer that used to calculate the CRC value
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* @param len: Length of the data buffer
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* @return CRC32 value
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*/
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uint32_t esp_rom_crc32_be(uint32_t crc, uint8_t const *buf, uint32_t len);
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/**
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* @brief CRC16 value in little endian.
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*
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* @param crc: Bitwise inverse of the CRC variant's initial value on the first
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* call, or the previous return value to continue a calculation
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* @param buf: Data buffer that used to calculate the CRC value
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* @param len: Length of the data buffer
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* @return CRC16 value
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*/
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uint16_t esp_rom_crc16_le(uint16_t crc, uint8_t const *buf, uint32_t len);
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/**
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* @brief CRC16 value in big endian.
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*
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* @param crc: Bitwise inverse of the CRC variant's initial value on the first
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* call, or the previous return value to continue a calculation
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* @param buf: Data buffer that used to calculate the CRC value
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* @param len: Length of the data buffer
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* @return CRC16 value
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*/
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uint16_t esp_rom_crc16_be(uint16_t crc, uint8_t const *buf, uint32_t len);
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/**
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* @brief CRC8 value in little endian.
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*
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* @param crc: Bitwise inverse of the CRC variant's initial value on the first
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* call, or the previous return value to continue a calculation
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* @param buf: Data buffer that used to calculate the CRC value
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* @param len: Length of the data buffer
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* @return CRC8 value
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*/
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uint8_t esp_rom_crc8_le(uint8_t crc, uint8_t const *buf, uint32_t len);
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/**
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* @brief CRC8 value in big endian.
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*
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* @param crc: Bitwise inverse of the CRC variant's initial value on the first
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* call, or the previous return value to continue a calculation
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* @param buf: Data buffer that used to calculate the CRC value
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* @param len: Length of the data buffer
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* @return CRC8 value
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*/
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uint8_t esp_rom_crc8_be(uint8_t crc, uint8_t const *buf, uint32_t len);
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#ifdef __cplusplus
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}
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#endif
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