esp-idf/components/esp_rom/include/esp32s2/rom/crc.h

// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ROM_CRC_H
#define ROM_CRC_H

#include <stdint.h>

#define ESP_ROM_HAS_CRC8LE      1
#define ESP_ROM_HAS_CRC16LE     1
#define ESP_ROM_HAS_CRC32LE     1

#ifdef __cplusplus
extern "C" {
#endif

/** \defgroup crc_apis, uart configuration and communication related apis
  * @brief crc apis
  */

/** @addtogroup crc_apis
  * @{
  */


/* Standard CRC8/16/32 algorithms. */
// CRC-8        x8+x2+x1+1              0x07
// CRC16-CCITT  x16+x12+x5+1   1021   ISO HDLC, ITU X.25, V.34/V.41/V.42, PPP-FCS
// CRC32:
//G(x) = x32 +x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x1 + 1
//If your buf is not continuous, you can use the first result to be the second parameter.

/**
  * @brief Crc32 value that is in little endian.
  *
  * @param  uint32_t crc : init crc value, use 0 at the first use.
  *
  * @param  uint8_t const *buf : buffer to start calculate crc.
  *
  * @param  uint32_t len : buffer length in byte.
  *
  * @return None
  */
uint32_t crc32_le(uint32_t crc, uint8_t const *buf, uint32_t len);

/**
  * @brief Crc16 value that is in little endian.
  *
  * @param  uint16_t crc : init crc value, use 0 at the first use.
  *
  * @param  uint8_t const *buf : buffer to start calculate crc.
  *
  * @param  uint32_t len : buffer length in byte.
  *
  * @return None
  */
uint16_t crc16_le(uint16_t crc, uint8_t const *buf, uint32_t len);

/**
  * @brief Crc8 value that is in little endian.
  *
  * @param  uint8_t crc : init crc value, use 0 at the first use.
  *
  * @param  uint8_t const *buf : buffer to start calculate crc.
  *
  * @param  uint32_t len : buffer length in byte.
  *
  * @return None
  */
uint8_t crc8_le(uint8_t crc, uint8_t const *buf, uint32_t len);

/**
  * @}
  */

#ifdef __cplusplus
}
#endif


#endif