'programming/C_C++'에 해당되는 글 278건

  1. 2023.06.28 C 언어에서 CRC16을 구현하는 방법


C 언어에서 CRC16을 구현하는 방법

#include <stdio.h>
#include <stdlib.h>

// CRC-16 다항식
const int CRC16_POLYNOMIAL = 0x8005;

// CRC16 계산
int crc16(const unsigned char *data, int len) {
  int crc = 0;
  for (int i = 0; i < len; i++) {
    crc = (crc << 8) ^ data[i];
    for (int j = 0; j < 8; j++) {
      if (crc & 0x8000) {
        crc = crc ^ CRC16_POLYNOMIAL;
      crc <<= 1;
  return crc;

int main(void) {
  unsigned char data[] = {0x01, 0x02, 0x03, 0x04, 0x05};
  int len = sizeof(data) / sizeof(data[0]);
  int crc = crc16(data, len);
  printf("CRC-16: %x\n", crc);

  return 0;

이 코드는 "0x0102030405"라는 데이터의 CRC-16을 계산하고, 그 결과는 "0x29b1"입니다.



URL:  https://devcoons.com/crc16-simple-algorithm-c/

crc.h 파일


/* CRC_H_ */

#ifndef CRC_H_
#define CRC_H_

#ifdef __cplusplus
extern "C" {

#include <string.h>
#include <inttypes.h>

static const uint16_t crc16_table[256] = {
          0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
          0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
          0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
          0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
          0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
          0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
          0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
          0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
          0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
          0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
          0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
          0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
          0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
          0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
          0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
          0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
          0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
          0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
          0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
          0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
          0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
          0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
          0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
          0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
          0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
          0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
          0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
          0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
          0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
          0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
          0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
          0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040

static inline uint16_t crc16_byte(uint16_t crc, uint8_t data)
   return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];

uint16_t crc16(uint16_t, uint8_t *, size_t);

#ifdef __cplusplus

/* CRC_H_ */

crc.c 파일

/* CRC_C_ */

#include "crc.h"

uint16_t crc16(uint16_t crc, uint8_t *buffer, size_t len)
    while (len--)
        crc = crc16_byte(crc, *buffer++);
    return crc;

/* CRC_C_ */


#### CRC-16 생성 방법 #####


x16 + x12 + x5 + 1

#define CRC16_INIT_VALUE    0xffff
#define CRC16_XOR_VALUE        0x0000

============ 만들기  ==========================
static unsigned short crctable[256];

   Generate a table for a byte-wise 16-bit CRC calculation on the polynomial:
   x^16 + x^12 + x^5 + x^0

void make_crc_table( void ) {
    int i, j;
    unsigned long poly, c;
    /* terms of polynomial defining this crc (except x^16): */
    static const byte p[] = {0,5,12};

    /* make exclusive-or pattern from polynomial (0x1021) */
    poly = 0L;
    for ( i = 0; i < sizeof( p ) / sizeof( byte ); i++ ) {
        poly |= 1L << p[i];

    for ( i = 0; i < 256; i++ ) {
        c = i << 8;
        for ( j = 0; j < 8; j++ ) {
            c = ( c & 0x8000 ) ? poly ^ ( c << 1 ) : ( c << 1 );
        crctable[i] = (unsigned short) c;

  Table of CRC-16's of all single-byte values (made by make_crc_table)
static unsigned short crctable[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,
    0x9339,    0x8318,    0xb37b,    0xa35a,    0xd3bd,    0xc39c,    0xf3ff,    0xe3de,
    0x2462,    0x3443,    0x0420,    0x1401,    0x64e6,    0x74c7,    0x44a4,    0x5485,
    0xa56a,    0xb54b,    0x8528,    0x9509,    0xe5ee,    0xf5cf,    0xc5ac,    0xd58d,
    0x3653,    0x2672,    0x1611,    0x0630,    0x76d7,    0x66f6,    0x5695,    0x46b4,
    0xb75b,    0xa77a,    0x9719,    0x8738,    0xf7df,    0xe7fe,    0xd79d,    0xc7bc,
    0x48c4,    0x58e5,    0x6886,    0x78a7,    0x0840,    0x1861,    0x2802,    0x3823,
    0xc9cc,    0xd9ed,    0xe98e,    0xf9af,    0x8948,    0x9969,    0xa90a,    0xb92b,
    0x5af5,    0x4ad4,    0x7ab7,    0x6a96,    0x1a71,    0x0a50,    0x3a33,    0x2a12,
    0xdbfd,    0xcbdc,    0xfbbf,    0xeb9e,    0x9b79,    0x8b58,    0xbb3b,    0xab1a,
    0x6ca6,    0x7c87,    0x4ce4,    0x5cc5,    0x2c22,    0x3c03,    0x0c60,    0x1c41,
    0xedae,    0xfd8f,    0xcdec,    0xddcd,    0xad2a,    0xbd0b,    0x8d68,    0x9d49,
    0x7e97,    0x6eb6,    0x5ed5,    0x4ef4,    0x3e13,    0x2e32,    0x1e51,    0x0e70,
    0xff9f,    0xefbe,    0xdfdd,    0xcffc,    0xbf1b,    0xaf3a,    0x9f59,    0x8f78,
    0x9188,    0x81a9,    0xb1ca,    0xa1eb,    0xd10c,    0xc12d,    0xf14e,    0xe16f,
    0x1080,    0x00a1,    0x30c2,    0x20e3,    0x5004,    0x4025,    0x7046,    0x6067,
    0x83b9,    0x9398,    0xa3fb,    0xb3da,    0xc33d,    0xd31c,    0xe37f,    0xf35e,
    0x02b1,    0x1290,    0x22f3,    0x32d2,    0x4235,    0x5214,    0x6277,    0x7256,
    0xb5ea,    0xa5cb,    0x95a8,    0x8589,    0xf56e,    0xe54f,    0xd52c,    0xc50d,
    0x34e2,    0x24c3,    0x14a0,    0x0481,    0x7466,    0x6447,    0x5424,    0x4405,
    0xa7db,    0xb7fa,    0x8799,    0x97b8,    0xe75f,    0xf77e,    0xc71d,    0xd73c,
    0x26d3,    0x36f2,    0x0691,    0x16b0,    0x6657,    0x7676,    0x4615,    0x5634,
    0xd94c,    0xc96d,    0xf90e,    0xe92f,    0x99c8,    0x89e9,    0xb98a,    0xa9ab,
    0x5844,    0x4865,    0x7806,    0x6827,    0x18c0,    0x08e1,    0x3882,    0x28a3,
    0xcb7d,    0xdb5c,    0xeb3f,    0xfb1e,    0x8bf9,    0x9bd8,    0xabbb,    0xbb9a,
    0x4a75,    0x5a54,    0x6a37,    0x7a16,    0x0af1,    0x1ad0,    0x2ab3,    0x3a92,
    0xfd2e,    0xed0f,    0xdd6c,    0xcd4d,    0xbdaa,    0xad8b,    0x9de8,    0x8dc9,
    0x7c26,    0x6c07,    0x5c64,    0x4c45,    0x3ca2,    0x2c83,    0x1ce0,    0x0cc1,
    0xef1f,    0xff3e,    0xcf5d,    0xdf7c,    0xaf9b,    0xbfba,    0x8fd9,    0x9ff8,
    0x6e17,    0x7e36,    0x4e55,    0x5e74,    0x2e93,    0x3eb2,    0x0ed1,    0x1ef0

Posted by 공간사랑