crc8校验查表法实现方法

/*CRC-8forDallasiButtonproductsFromMaxim/DallasAPNote27"UnderstandingandUsingCyclicRedundancyCheckswithDallasSemiconductoriButtonProducts"TheApnotedescribestheCRC-8algorithmusedintheiButtonproducts.Theirimplementationinvolvesa256byteCRCtable.Thisalgorithmisimplementedhere.Inadditiontwootheralgorithmsareshown.Oneusesnibblearraysandtheotherusesbooleanarithmetic.18JAN03-T.ScottDattalo*//*crcarrayfromtheMaximApNote*/unsignedcharcrc_array[256]={0x00,0x5e,0xbc,0xe2,0x61,0x3f,0xdd,0x83,0xc2,0x9c,0x7e,0x20,0xa3,0xfd,0x1f,0x41,0x9d,0xc3,0x21,0x7f,0xfc,0xa2,0x40,0x1e,0x5f,0x01,0xe3,0xbd,0x3e,0x60,0x82,0xdc,0x23,0x7d,0x9f,0xc1,0x42,0x1c,0xfe,0xa0,0xe1,0xbf,0x5d,0x03,0x80,0xde,0x3c,0x62,0xbe,0xe0,0x02,0x5c,0xdf,0x81,0x63,0x3d,0x7c,0x22,0xc0,0x9e,0x1d,0x43,0xa1,0xff,0x46,0x18,0xfa,0xa4,0x27,0x79,0x9b,0xc5,0x84,0xda,0x38,0x66,0xe5,0xbb,0x59,0x07,0xdb,0x85,0x67,0x39,0xba,0xe4,0x06,0x58,0x19,0x47,0xa5,0xfb,0x78,0x26,0xc4,0x9a,0x65,0x3b,0xd9,0x87,0x04,0x5a,0xb8,0xe6,0xa7,0xf9,0x1b,0x45,0xc6,0x98,0x7a,0x24,0xf8,0xa6,0x44,0x1a,0x99,0xc7,0x25,0x7b,0x3a,0x64,0x86,0xd8,0x5b,0x05,0xe7,0xb9,0x8c,0xd2,0x30,0x6e,0xed,0xb3,0x51,0x0f,0x4e,0x10,0xf2,0xac,0x2f,0x71,0x93,0xcd,0x11,0x4f,0xad,0xf3,0x70,0x2e,0xcc,0x92,0xd3,0x8d,0x6f,0x31,0xb2,0xec,0x0e,0x50,0xaf,0xf1,0x13,0x4d,0xce,0x90,0x72,0x2c,0x6d,0x33,0xd1,0x8f,0x0c,0x52,0xb0,0xee,0x32,0x6c,0x8e,0xd0,0x53,0x0d,0xef,0xb1,0xf0,0xae,0x4c,0x12,0x91,0xcf,0x2d,0x73,0xca,0x94,0x76,0x28,0xab,0xf5,0x17,0x49,0x08,0x56,0xb4,0xea,0x69,0x37,0xd5,0x8b,0x57,0x09,0xeb,0xb5,0x36,0x68,0x8a,0xd4,0x95,0xcb,0x29,0x77,0xf4,0xaa,0x48,0x16,0xe9,0xb7,0x55,0x0b,0x88,0xd6,0x34,0x6a,0x2b,0x75,0x97,0xc9,0x4a,0x14,0xf6,0xa8,0x74,0x2a,0xc8,0x96,0x15,0x4b,0xa9,0xf7,0xb6,0xe8,0x0a,0x54,0xd7,0x89,0x6b,0x35,};unsignedcharr1[16]={0x00,0x5e,0xbc,0xe2,0x61,0x3f,0xdd,0x83,0xc2,0x9c,0x7e,0x20,0xa3,0xfd,0x1f,0x41,};unsignedcharr2[16]={0x00,0x9d,0x23,0xbe,0x46,0xdb,0x65,0xf8,0x8c,0x11,0xaf,0x32,0xca,0x57,0xe9,0x74};/*crc-globalcrcstoredhere*/unsignedcharcrc;/*===========================================================*/unsignedcharcrc_bits(intdata){inti=(data^crc)&0xff;crc=0;if(i&1)crc^=0x5e;if(i&2)crc^=0xbc;if(i&4)crc^=0x61;if(i&8)crc^=0xc2;if(i&0x10)crc^=0x9d;if(i&0x20)crc^=0x23;if(i&0x40)crc^=0x46;if(i&0x80)crc^=0x8c;returncrc;}/*===========================================================*/unsignedcharcrc_table(intdata){inti=(data^crc)&0xff;crc =crc_array[(data^crc)&0xff];returncrc;}/*===========================================================*/unsignedcharcrc_nibbles(intdata){inti=(data^crc)&0xff;crc=r1[i&0xf]^r2[i>>4];returncrc;}/*===========================================================*//*crc8-testallthreecrcalgorithms*/unsignedcharcrc8(intdata){unsignedcharc;c=crc;crc_table(data);printf("0xx0xx",data,crc);crc=c;crc_bits(data);printf("0xx",crc);crc=c;crc_nibbles(data);printf("0xx\n",crc);returncrc;}/*===========================================================*/intmain(intargc,char**argv){inti;crc=0xff;/*Standardcheckforthestring"123456789"*/for(i='1';i<='9';i){crc8(i);printf("%d0xx\n",i,crc);}printf("\n----\n\n");/*OrthogonalcheckSetthecrc=0anddata=2^nandcomputenewcrc*/crc=0x00;crc8(1);crc=0x00;crc8(2);crc=0x00;crc8(4);crc=0x00;crc8(8);crc=0x00;crc8(16);crc=0x00;crc8(32);crc=0x00;crc8(64);crc=0x00;crc8(128);/*CRCexampleintheDallasAPNote*/crc=0;i=0x02;printf("%3x0xx\n",i,crc8(i));i=0x1c;printf("%3x0xx\n",i,crc8(i));i=0xb8;printf("%3x0xx\n",i,crc8(i));i=0x01;printf("%3x0xx\n",i,crc8(i));i=0x00;printf("%3x0xx\n",i,crc8(i));i=0x00;printf("%3x0xx\n",i,crc8(i));i=0x00;printf("%3x0xx\n",i,crc8(i));i=0xa2;printf("%3x0xx\n",i,crc8(i));return0;}