?? crc16.c
字號:
包含三種方法的計算 CRC16 校驗（查表、計算、查表＋計算）- -
附件 RTX51中容易混淆的幾個問題.doc：http://blog.blogchina.com/upload/2004-11-17/200411170906168061.doc/////////////////////////////////////////////////////
//文件: crc.c //
//功能: 計算 CRC16 校驗 //
//作者: 邵子揚 shaoziyang@126.com //
//時間: 2004-Fer-26 //
//版本: 1.0 //
//說明: 這是針對PIC的版本，對于Keil51需要將下面數組//
// 中的const換成code //
//-------------------------------------------------//
//修改: //
// 版本: 1.2 //
// 作者:邵子揚 //
// 時間:2004-Oct-12 //
// 原因:程序優化，計算花費的時間更短。經過模擬仿真//
// ，計算100個數據的速度提高27% //
//-------------------------------------------------//
// 版本: 1.4 //
// 作者:邵子揚 //
// 時間:2004-Oct-20 //
// 原因:將三種計算方法合在一個文件中，根據實際需要//
// 選擇，用宏定義區分，默認查表法 //
// Method_Calc 計算法 //
// Method_TableCalc 計算＋查表 //
// Method_Table 查表 //
// __ __ //
// by ( / _ _/ '(__/_ _ //
// 2004 __)/)(/()/__/ / (//)(/ @126.com //
// _/ //
/////////////////////////////////////////////////////
//#define Method_Calc
//#define Method_TableCalc
#if !defined(Method_Table) && \
!defined(Method_Calc) && \
!defined(Method_TableCalc)
#define Method_Table
#endif
void crc16(unsigned char *buf,unsigned char n,unsigned char *h,unsigned char *l);
#if defined(Method_Table)
//查表
const unsigned char crctableh[256]={
0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
0x81, 0x91, 0xA1, 0xB1, 0xC1, 0xD1, 0xE1, 0xF1,
0x12, 0x02, 0x32, 0x22, 0x52, 0x42, 0x72, 0x62,
0x93, 0x83, 0xB3, 0xA3, 0xD3, 0xC3, 0xF3, 0xE3,
0x24, 0x34, 0x04, 0x14, 0x64, 0x74, 0x44, 0x54,
0xA5, 0xB5, 0x85, 0x95, 0xE5, 0xF5, 0xC5, 0xD5,
0x36, 0x26, 0x16, 0x06, 0x76, 0x66, 0x56, 0x46,
0xB7, 0xA7, 0x97, 0x87, 0xF7, 0xE7, 0xD7, 0xC7,
0x48, 0x58, 0x68, 0x78, 0x08, 0x18, 0x28, 0x38,
0xC9, 0xD9, 0xE9, 0xF9, 0x89, 0x99, 0xA9, 0xB9,
0x5A, 0x4A, 0x7A, 0x6A, 0x1A, 0x0A, 0x3A, 0x2A,
0xDB, 0xCB, 0xFB, 0xEB, 0x9B, 0x8B, 0xBB, 0xAB,
0x6C, 0x7C, 0x4C, 0x5C, 0x2C, 0x3C, 0x0C, 0x1C,
0xED, 0xFD, 0xCD, 0xDD, 0xAD, 0xBD, 0x8D, 0x9D,
0x7E, 0x6E, 0x5E, 0x4E, 0x3E, 0x2E, 0x1E, 0x0E,
0xFF, 0xEF, 0xDF, 0xCF, 0xBF, 0xAF, 0x9F, 0x8F,
0x91, 0x81, 0xB1, 0xA1, 0xD1, 0xC1, 0xF1, 0xE1,
0x10, 0x00, 0x30, 0x20, 0x50, 0x40, 0x70, 0x60,
0x83, 0x93, 0xA3, 0xB3, 0xC3, 0xD3, 0xE3, 0xF3,
0x02, 0x12, 0x22, 0x32, 0x42, 0x52, 0x62, 0x72,
0xB5, 0xA5, 0x95, 0x85, 0xF5, 0xE5, 0xD5, 0xC5,
0x34, 0x24, 0x14, 0x04, 0x74, 0x64, 0x54, 0x44,
0xA7, 0xB7, 0x87, 0x97, 0xE7, 0xF7, 0xC7, 0xD7,
0x26, 0x36, 0x06, 0x16, 0x66, 0x76, 0x46, 0x56,
0xD9, 0xC9, 0xF9, 0xE9, 0x99, 0x89, 0xB9, 0xA9,
0x58, 0x48, 0x78, 0x68, 0x18, 0x08, 0x38, 0x28,
0xCB, 0xDB, 0xEB, 0xFB, 0x8B, 0x9B, 0xAB, 0xBB,
0x4A, 0x5A, 0x6A, 0x7A, 0x0A, 0x1A, 0x2A, 0x3A,
0xFD, 0xED, 0xDD, 0xCD, 0xBD, 0xAD, 0x9D, 0x8D,
0x7C, 0x6C, 0x5C, 0x4C, 0x3C, 0x2C, 0x1C, 0x0C,
0xEF, 0xFF, 0xCF, 0xDF, 0xAF, 0xBF, 0x8F, 0x9F,
0x6E, 0x7E, 0x4E, 0x5E, 0x2E, 0x3E, 0x0E, 0x1E,
};
const unsigned char crctablel[256]={
0x00, 0x21, 0x42, 0x63, 0x84, 0xA5, 0xC6, 0xE7,
0x08, 0x29, 0x4A, 0x6B, 0x8C, 0xAD, 0xCE, 0xEF,
0x31, 0x10, 0x73, 0x52, 0xB5, 0x94, 0xF7, 0xD6,
0x39, 0x18, 0x7B, 0x5A, 0xBD, 0x9C, 0xFF, 0xDE,
0x62, 0x43, 0x20, 0x01, 0xE6, 0xC7, 0xA4, 0x85,
0x6A, 0x4B, 0x28, 0x09, 0xEE, 0xCF, 0xAC, 0x8D,
0x53, 0x72, 0x11, 0x30, 0xD7, 0xF6, 0x95, 0xB4,
0x5B, 0x7A, 0x19, 0x38, 0xDF, 0xFE, 0x9D, 0xBC,
0xC4, 0xE5, 0x86, 0xA7, 0x40, 0x61, 0x02, 0x23,
0xCC, 0xED, 0x8E, 0xAF, 0x48, 0x69, 0x0A, 0x2B,
0xF5, 0xD4, 0xB7, 0x96, 0x71, 0x50, 0x33, 0x12,
0xFD, 0xDC, 0xBF, 0x9E, 0x79, 0x58, 0x3B, 0x1A,
0xA6, 0x87, 0xE4, 0xC5, 0x22, 0x03, 0x60, 0x41,
0xAE, 0x8F, 0xEC, 0xCD, 0x2A, 0x0B, 0x68, 0x49,
0x97, 0xB6, 0xD5, 0xF4, 0x13, 0x32, 0x51, 0x70,
0x9F, 0xBE, 0xDD, 0xFC, 0x1B, 0x3A, 0x59, 0x78,
0x88, 0xA9, 0xCA, 0xEB, 0x0C, 0x2D, 0x4E, 0x6F,
0x80, 0xA1, 0xC2, 0xE3, 0x04, 0x25, 0x46, 0x67,
0xB9, 0x98, 0xFB, 0xDA, 0x3D, 0x1C, 0x7F, 0x5E,
0xB1, 0x90, 0xF3, 0xD2, 0x35, 0x14, 0x77, 0x56,
0xEA, 0xCB, 0xA8, 0x89, 0x6E, 0x4F, 0x2C, 0x0D,
0xE2, 0xC3, 0xA0, 0x81, 0x66, 0x47, 0x24, 0x05,
0xDB, 0xFA, 0x99, 0xB8, 0x5F, 0x7E, 0x1D, 0x3C,
0xD3, 0xF2, 0x91, 0xB0, 0x57, 0x76, 0x15, 0x34,
0x4C, 0x6D, 0x0E, 0x2F, 0xC8, 0xE9, 0x8A, 0xAB,
0x44, 0x65, 0x06, 0x27, 0xC0, 0xE1, 0x82, 0xA3,
0x7D, 0x5C, 0x3F, 0x1E, 0xF9, 0xD8, 0xBB, 0x9A,
0x75, 0x54, 0x37, 0x16, 0xF1, 0xD0, 0xB3, 0x92,
0x2E, 0x0F, 0x6C, 0x4D, 0xAA, 0x8B, 0xE8, 0xC9,
0x26, 0x07, 0x64, 0x45, 0xA2, 0x83, 0xE0, 0xC1,
0x1F, 0x3E, 0x5D, 0x7C, 0x9B, 0xBA, 0xD9, 0xF8,
0x17, 0x36, 0x55, 0x74, 0x93, 0xB2, 0xD1, 0xF0,
};
void crc16(unsigned char *buf,unsigned char n,unsigned char *h,unsigned char *l)
{
unsigned char i,t,a,b;
a = b = 0;
/* while(n != 0)
{
t = a ^ *buf;
a = b ^ crctableh[t];
b = crctablel[t];
n --;
buf ++;
}*/
for(i=0;i {
t = a ^ buf[i];
a = b ^ crctableh[t];
b = crctablel[t];
}
*h = a;
*l = b;
}
#elif defined(Method_Calc)
//計算
void crc16(unsigned char *buf,unsigned char n,unsigned char *h,unsigned char *l)
{
unsigned char i,t;
union
{
unsigned char c[2];
unsigned int x;
}crc;
crc.x = 0;
while(n > 0)
{
crc.c[0] ^= *buf;
for(i = 8;i > 0;i --)
{
t = crc.c[0];
crc.x <<= 1;
if( t & 0x80)crc.x ^= 0x1021;
}
buf ++;
n --;
}
*h = crc.c[0];
*l = crc.c[1];
}
#elif defined(Method_TableCalc)
//查表＋計算
void crc16(unsigned char *buf,unsigned char n,unsigned char *h,unsigned char *l)
{
unsigned char t;
const unsigned int crch[16]= // CRC余式表
{
0x00,0x10,0x20,0x30,0x40,0x50,0x60,0x70,
0x81,0x91,0xa1,0xb1,0xc1,0xd1,0xe1,0xf1,
};
const unsigned int crcl[16]= // CRC余式表
{
0x00,0x21,0x42,0x63,0x84,0xa5,0xc6,0xe7,
0x08,0x29,0x4a,0x6b,0x8c,0xad,0xce,0xef,
};
union
{
unsigned char c[2];
unsigned int x;
}crc;
crc.x=0;
while( n -- != 0)
{
t = (crc.c[0] / 16) ^ (*buf / 16);
crc.x <<= 4;
crc.c[0] ^= crch[t];
crc.c[1] ^= crcl[t];
t = (crc.c[0] / 16) ^ (*buf % 16);
crc.x <<= 4;
crc.c[0] ^= crch[t];
crc.c[1] ^= crcl[t];
buf ++;
}
*h = crc.c[0];
*l = crc.c[1];
}
#endif
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