// // NSString+WithCRCModbus.m // iOS-CRC // // Created by leon on 2017/3/7. // // /** * CRC在线检验网址:https://www.lammertbies.nl/comm/info/crc-calculation.html * http://stackoverflow.com/questions/33794878/when-converting-nsdata-to-unsigned-char-i-get-the-wrong-result * http://stackoverflow.com/questions/10214990/how-to-convert-nsdata-to-char-array-containing-hexa-values * http://stackoverflow.com/questions/12971117/how-to-convert-nsdata-to-char */ #import "NSString+WithCRCModbus.h" @implementation NSString (WithCRCModbus) - (NSString*)withCrc16CCITT{ if(self.length%2!=0){ return nil; } return [self stringByAppendingString:[self getCrcString2]]; } uint16_t xmodem_crc16_ccitt_2(const uint8_t *pbBuf, uint32_t dwLen) { uint16_t wCRC = 0; uint16_t bCycle; while (dwLen-- > 0) { wCRC ^= (unsigned short) *pbBuf++ << 8; for (bCycle = 0; bCycle < 8; bCycle++) { if (wCRC & 0x8000) { wCRC = wCRC << 1 ^ 0x1021; } else { wCRC <<= 1; } } } return wCRC; } - (NSString*)getCrcString2{ NSData *nsdataString = [self toNSData]; unsigned char *chars = (unsigned char *)[nsdataString bytes]; // unsigned short result = [self CRC16:chars length:nsdataString.length]; unsigned short result = xmodem_crc16_ccitt_2(chars, nsdataString.length); //下面这种方式方可，直接用dataWithBytes传short的地址可能导致字节反序 // 参考：http://www.jianshu.com/p/0d8cf741584a Byte b1=result & 0xff; Byte b2=(result>>8) & 0xff; Byte byte[] = {b1, b2}; NSData *data = [NSData dataWithBytes:byte length:sizeof(byte)]; return [self toNSString:data]; } - (NSString*)withCrc16Modbus{ if(self.length%2!=0){ return nil; } return [self stringByAppendingString:[self getCrcString]]; } - (NSString*)getCrcString{ NSData *nsdataString = [self toNSData]; unsigned char *chars = (unsigned char *)[nsdataString bytes]; unsigned short result = [self CRC16:chars length:nsdataString.length]; //下面这种方式方可，直接用dataWithBytes传short的地址可能导致字节反序 // 参考：http://www.jianshu.com/p/0d8cf741584a Byte b1=result & 0xff; Byte b2=(result>>8) & 0xff; Byte byte[] = {b1, b2}; NSData *data = [NSData dataWithBytes:byte length:sizeof(byte)]; return [self toNSString:data]; } // http://liumh.com/2015/06/06/convert-between-nsdata-and-hexstr/ - (NSData *)toNSData{ if (!self || [self length] == 0) { return nil; } NSMutableData *hexData = [[NSMutableData alloc] initWithCapacity:8]; NSRange range; if ([self length] % 2 == 0) { range = NSMakeRange(0, 2); } else { range = NSMakeRange(0, 1); } for (NSInteger i = range.location; i < [self length]; i += 2) { unsigned int anInt; NSString *hexCharStr = [self substringWithRange:range]; NSScanner *scanner = [[NSScanner alloc] initWithString:hexCharStr]; [scanner scanHexInt:&anInt]; NSData *entity = [[NSData alloc] initWithBytes:&anInt length:1]; [hexData appendData:entity]; range.location += range.length; range.length = 2; } return hexData; } // http://liumh.com/2015/06/06/convert-between-nsdata-and-hexstr/ - (NSString *)toNSString:(NSData*)data{ if (!self || [self length] == 0) { return @""; } NSMutableString *string = [[NSMutableString alloc] initWithCapacity:[self length]]; [data enumerateByteRangesUsingBlock:^(const void *bytes, NSRange byteRange, BOOL *stop) { unsigned char *dataBytes = (unsigned char*)bytes; for (NSInteger i = 0; i < byteRange.length; i++) { NSString *hexStr = [NSString stringWithFormat:@"%x", (dataBytes[i]) & 0xff]; if ([hexStr length] == 2) { [string appendString:hexStr]; } else { [string appendFormat:@"0%@", hexStr]; } } }]; return string; } const char chCRCHTalbe[]={ 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40 }; const char chCRCLTalbe[] = { 0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3, 0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26, 0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5, 0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C, 0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83, 0x41, 0x81, 0x80, 0x40 }; /* *decription: 计算CRC校验码 *input: 无符号进制字符串数组 *output: CRC检验码 */ -(unsigned short)CRC16:(unsigned char *)puchMsg length:(unsigned int) usDataLen { unsigned char chCRCHi = 0xFF; // 高CRC字节初始化 unsigned char chCRCLo = 0xFF; // 低CRC字节初始化 unsigned short wIndex; while(usDataLen--) { wIndex = chCRCLo ^ *puchMsg++ ; chCRCLo = chCRCHi ^ chCRCHTalbe[wIndex]; chCRCHi = chCRCLTalbe[wIndex] ; } return ((chCRCHi << 8) | chCRCLo) ; } @end