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sys/checksum: Adding three new crc16 variations #18516

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sys/checksum: Adding three new crc16 variations #18516

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69 changes: 64 additions & 5 deletions sys/checksum/crc16_ccitt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,42 @@

#include "checksum/crc16_ccitt.h"

static const uint16_t _crc16_lookuptable[256] = {
static const uint16_t crc_ccitt_lookuptable[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};

static const uint16_t _crc16_ccitt_false_lookuptable[256] = {
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
Expand Down Expand Up @@ -58,16 +93,40 @@ static const uint16_t _crc16_lookuptable[256] = {
0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
};

uint16_t crc16_ccitt_update(uint16_t crc, const unsigned char *buf, size_t len)
uint16_t crc16_ccitt_kermit_update(uint16_t crc, const unsigned char *buf, size_t len)
{
while (len--) {
crc = (crc >> 8) ^ crc_ccitt_lookuptable[(crc ^ (*buf++)) & 0xff];
}

return crc;
}

uint16_t crc16_ccitt_kermit_calc(const unsigned char *buf, size_t len)
{
return crc16_ccitt_kermit_update(0x0000, buf, len);
}

uint16_t crc16_ccitt_mcrf4xx_calc(const unsigned char *buf, size_t len)
{
return crc16_ccitt_kermit_update(0xFFFF, buf, len);
}

uint16_t crc16_ccitt_false_update(uint16_t crc, const unsigned char *buf, size_t len)
{
while (len--) {
crc = ((crc << 8) ^ _crc16_lookuptable[((crc >> 8) ^ ((*buf++) & 0x00FF))]);
crc = ((crc << 8) ^ _crc16_ccitt_false_lookuptable[((crc >> 8) ^ ((*buf++) & 0x00FF))]);
}

return crc;
}

uint16_t crc16_ccitt_calc(const unsigned char *buf, size_t len)
uint16_t crc16_ccitt_aug_calc(const unsigned char *buf, size_t len)
{
return crc16_ccitt_false_update(0x1D0F, buf, len);
}

uint16_t crc16_ccitt_false_calc(const unsigned char *buf, size_t len)
{
return crc16_ccitt_update(0x1D0F, buf, len);
return crc16_ccitt_false_update(0xFFFF, buf, len);
}
174 changes: 162 additions & 12 deletions sys/include/checksum/crc16_ccitt.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,21 +10,18 @@
* @defgroup sys_checksum_crc16_ccitt CRC16-CCITT
* @ingroup sys_checksum
*
* @brief CRC16-CCITT checksum algorithm
* @details This implementation of CRC16 is based on the CCITT
* specification using 0x1D0F as a start value.
* Using a different start value is possible by calling
* crc16_ccitt_update() with the desired start value
* instead of crc16_ccitt_calc().
*
* @brief Variations of CRC16-CCITT checksum algorithms
* @details This provides implementations for multiple variations
* of CRC16 checks.
* There is a more generalized version in @ref sys_checksum_ucrc16,
* that does not utilize a look-up table as this implementation
* does (and is thus also for more memory efficient). Its caveat
* however is that it is slower by about factor 8 than this version.
* that does not utilize a look-up table as these implementation
* do (and is thus also far more memory efficient). Its caveat
* however is that it is slower by about factor 8 than these versions.
*
* @{
* @file
* @author Ludwig Knüpfer <[email protected]>
* @author Bennet Blischke <[email protected]>
*/

#ifndef CHECKSUM_CRC16_CCITT_H
Expand All @@ -37,8 +34,153 @@
extern "C" {
#endif

/**
* @brief Update CRC16-CCITT-KERMIT
*
* @param[in] crc A start value for the CRC calculation, usually the
* return value of a previous call to
* crc16_ccitt_kermit_calc() or crc16_ccitt_kermit_update()
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area based on the
* given start value
*/
uint16_t crc16_ccitt_kermit_update(uint16_t crc, const unsigned char *buf, size_t len);

/**
* @brief Calculate CRC16-CCITT-KERMIT
*
* Parameter | Value
* --------: | :----
* Polynom | `0x1021`
* Init | `0x0000`
* Refin | `true`
* Refout | `true`
* Xorout | `0x0000`
* Check | `0x2189`
*
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area
*/
uint16_t crc16_ccitt_kermit_calc(const unsigned char *buf, size_t len);

/**
* @brief Update CRC16-CCITT-MCRF4XX
*
* @param[in] crc A start value for the CRC calculation, usually the
* return value of a previous call to
* crc16_ccitt_mcrf4xx_calc() or crc16_ccitt_mcrf4xx_update()
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area based on the
* given start value
*/
static inline uint16_t crc16_ccitt_mcrf4xx_update(uint16_t crc, const unsigned char *buf,
size_t len)
{
/* Since CCITT-KERMIT and CCITT-MCRF4XX only differ in the starting
* seed, we wrap around crc16_ccitt_kermit_update() for updating */
return crc16_ccitt_kermit_update(crc, buf, len);
}

/**
* @brief Calculate CRC16-CCITT-MCRF4XX
*
* Parameter | Value
* --------: | :----
* Polynom | `0x1021`
* Init | `0xffff`
* Refin | `true`
* Refout | `true`
* Xorout | `0x0000`
* Check | `0x6f91`
*
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area
*/
uint16_t crc16_ccitt_mcrf4xx_calc(const unsigned char *buf, size_t len);

/**
* @brief Update CRC16-CCITT-FALSE
*
* @param[in] crc A start value for the CRC calculation, usually the
* return value of a previous call to
* crc16_ccitt_false_calc() or crc16_ccitt_false_update()
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area based on the
* given start value
*/
uint16_t crc16_ccitt_false_update(uint16_t crc, const unsigned char *buf, size_t len);

/**
* @brief Calculate CRC16-CCITT-FALSE
*
* Parameter | Value
* --------: | :----
* Polynom | `0x1021`
* Init | `0xffff`
* Refin | `false`
* Refout | `false`
* Xorout | `0x0000`
* Check | `0x29b1`
*
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area
*/
uint16_t crc16_ccitt_false_calc(const unsigned char *buf, size_t len);

/**
* @brief Update CRC16-CCITT-AUG
*
* @param[in] crc A start value for the CRC calculation, usually the
* return value of a previous call to
* crc16_ccitt_aug_calc() or crc16_ccitt_aug_update()
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area based on the
* given start value
*/
static inline uint16_t crc16_ccitt_aug_update(uint16_t crc, const unsigned char *buf, size_t len)
{
/* Since CCITT-AUG and CCITT-FALSE only differ in the starting
* seed, we wrap around crc16_ccitt_false_update() for updating */
return crc16_ccitt_false_update(crc, buf, len);
}

/**
* @brief Calculate CRC16-CCITT-AUG
*
* Parameter | Value
* --------: | :----
* Polynom | `0x1021`
* Init | `0x1d0f`
* Refin | `false`
* Refout | `false`
* Xorout | `0x0000`
* Check | `0xe5cc`
*
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area
*/
uint16_t crc16_ccitt_aug_calc(const unsigned char *buf, size_t len);

/**
* @brief Update CRC16-CCITT
* @deprecated Use @ref crc16_ccitt_aug_update instead.
* Will be removed after 2023.01 release.
*
* @param[in] crc A start value for the CRC calculation, usually the
* return value of a previous call to
Expand All @@ -49,17 +191,25 @@ extern "C" {
* @return Checksum of the specified memory area based on the
* given start value
*/
uint16_t crc16_ccitt_update(uint16_t crc, const unsigned char *buf, size_t len);
static inline uint16_t crc16_ccitt_update(uint16_t crc, const unsigned char *buf, size_t len)
{
return crc16_ccitt_false_update(crc, buf, len);
}

/**
* @brief Calculate CRC16-CCITT
* @deprecated Use @ref crc16_ccitt_aug_calc instead.
* Will be removed after 2023.01 release.
*
* @param[in] buf Start of the memory area to checksum
* @param[in] len Number of bytes to checksum
*
* @return Checksum of the specified memory area
*/
uint16_t crc16_ccitt_calc(const unsigned char *buf, size_t len);
static inline uint16_t crc16_ccitt_calc(const unsigned char *buf, size_t len)
{
return crc16_ccitt_aug_calc(buf, len);
}

#ifdef __cplusplus
}
Expand Down
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