crc.c

此软件是CRC的软件实现方法

/****************************************************************
 *文件名：crc.c
 *描述：CRC校验计算，包括CRC8与CRC16的计算方法。
 *环境：任意
 *版本：v1.0
 *作者：wentsing
 *日期：2006/03/07
******************************************************************/

#include "include.h"

#define CRC_C		1

#if CRC8

/****************************************************************
 *函数性质：公共
 *入口：要进行CRC校验的数据缓冲unsigned char *ptr，要进行CRC校验的数据长度
 *出口：CRC计算结果
 *功能：CRC8计算
 *调用方式：unsigned char CalCRC8( unsigned char *ptr,unsigned char len)
*****************************************************************/
#if KEILC51
unsigned char code dscrc_table[] = {
#else
const unsigned char dscrc_table[] = {
#endif
        0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
      157,195, 33,127,252,162, 64, 30, 95,  1,227,189, 62, 96,130,220,
       35,125,159,193, 66, 28,254,160,225,191, 93,  3,128,222, 60, 98,
      190,224,  2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
       70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89,  7,
      219,133,103, 57,186,228,  6, 88, 25, 71,165,251,120, 38,196,154,
      101, 59,217,135,  4, 90,184,230,167,249, 27, 69,198,152,122, 36,
      248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91,  5,231,185,
      140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
       17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
      175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
       50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
      202,148,118, 40,171,245, 23, 73,  8, 86,180,234,105, 55,213,139,
       87,  9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
      233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
      116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};

unsigned char CalCRC8( unsigned char *ptr,unsigned char len)
{
	unsigned char i,crc = 0;
	while(len--!0)
	{
		crc = dscrc_table[crc ^ *ptr];
		ptr++;
	}
	return crc;
}
#endif


/****************************************************************
 *函数性质：公共
 *入口：要进行CRC校验的数据缓冲unsigned char *ptr，要进行CRC校验的数据长度
 *出口：CRC计算结果
 *功能：CRC16计算（计算速度慢，程序空间小）
 *调用方式：unsigned short CalCRC16Slow(unsigned char *ptr, unsigned char len)
*****************************************************************/
#if CRC16 == CRC16SLOW
unsigned short CalCRC16Slow(unsigned char *ptr, unsigned char len)
{
	unsigned char i;
	unsigned short crc = 0;
	while(len--!=0) 
	{
		for(i = 0x80; i != 0; i/=2) 
		{
			if((crc&0x8000)!=0) 
			{
				crc*=2; 
				crc^=0x1021;
			}											/* 余式CRC乘以2再求CRC  */
			else crc*=2;
			if((*ptr&i)!=0) crc^=0x1021;				/* 再加上本位的CRC */
		}
		ptr++;
	}
	return(crc);
}
#endif


/****************************************************************
 *函数性质：公共
 *入口：要进行CRC校验的数据缓冲unsigned char *ptr，要进行CRC校验的数据长度
 *出口：CRC计算结果
 *功能：CRC16计算（计算速度快，程序空间大）
 *调用方式：unsigned short CalCRC16Quick(unsigned char *ptr,  unsigned char len) 
*****************************************************************/
#if CRC16 == CRC16QUICK

#if KEILC51
unsigned char code crc_ta[256] = {
#else
const unsigned short crc_ta[256] = {					/* CRC余式表 */
#endif
    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
	};
unsigned short CalCRC16Quick(unsigned char *ptr,  unsigned char len) 
{
	unsigned short crc;
	unsigned char da;

	crc=0;
	while(len--!=0) {
	da=(unsigned char) (crc/256);						/* 以8位二进制数的形式暂存CRC的高8位 */
	crc<<=8;											/* 左移8位，相当于CRC的低8位乘以  */
	crc^=crc_ta[da^*ptr];								/* 高8位和当前字节相加后再查表求CRC ，再加上以前的CRC */
	ptr++;
	}
	return(crc);
}
#endif


/****************************************************************
 *函数性质：公共
 *入口：要进行CRC校验的数据缓冲unsigned char *ptr，要进行CRC校验的数据长度
 *出口：CRC计算结果
 *功能：CRC16计算（计算速度折中，程序空间折中）
 *调用方式：unsigned short CalCRC16Mid(unsigned char *ptr,  unsigned char len)
*****************************************************************/
#if CRC16 == CRC16MID
#if KEILC51
unsigned short code crc_ta[16] = {
#else
const unsigned short crc_ta[16]={						/* CRC余式表 */
#endif
    0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
	0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef
	};
unsigned short CalCRC16Mid(unsigned char *ptr,  unsigned char len)
{
	unsigned short crc;
	unsigned char da;

	crc = 0;
	while(len--!=0) 
	{
		da = ((unsigned char)(crc/256))/16;				/* 暂存CRC的高四位 */
		crc<<=4;										/* CRC右移4位，相当于取CRC的低12位）*/
		crc^=crc_ta[da^(*ptr/16)];						/* CRC的高4位和本字节的前半字节相加后查表计算CRC，然后加上上一次CRC的余数 */
		da = ((unsigned char)(crc/256))/16;				/* 暂存CRC的高4位 */
		crc<<=4;										/* CRC右移4位， 相当于CRC的低12位） */
		crc^=crc_ta[da^(*ptr&0x0f)];					/* CRC的高4位和本字节的后半字节相加后查表计算CRC，然后再加上上一次CRC的余数 */
		ptr++;
	}
	return(crc);
}
#endif