计算机基础 —— 海明码 (C++实现)

 
     附 海明码原理校验方法

前言

     海明（汉明）码是广泛采用的一种有效的校验码，它实际上是一种多重奇偶校验码。

     海明码的原理就是在有效信息位中加入几个校验位形成海明码，并把海明码的每一个二进制分配到几个奇偶校验中。当某一位出错的时候，不仅能检错，还能发现出错位的位置。假设校验位有k位，那么校验码最多有2k个，显然其中有一个校验码是正确的，那么就能校验出2k-1个错位。所以，如果能满足一个n位数n+k<=2k-1,则在理论上即可判断出哪一位数出错。

C++代码

     C++实现海明码如下代码，Vs2017编译通过。

#define JHM(value)  ((value==1||value==49)?1:(value==0||value==48)?0:0)// 支持序列长度为:3~11位
char *TrickTest::TotalHMCodec(char *hm)
{if (!hm) { return nullptr; }// 计算k k^2≥k+n+1unsigned short hmLen = strlen(hm);if (hmLen <= 1) { return nullptr; }	unsigned short K = 0;if (hmLen <= 4)			{ K = 3; }else if (hmLen <= 11)	{ K = 4; }else if (hmLen <= 26)	{ K = 5; }else if (hmLen <= 26)	{ K = 5; }// 创建处理新字符串int *HM = new int[hmLen * sizeof(int)], *pHM = HM;memset(HM, 0, hmLen * sizeof(int));for (short index = hmLen - 1; index >= 0; *pHM++ = hm[index], --index);pHM = nullptr;// 构建表格const unsigned short tableLen = K + hmLen;char *tableBuf = new char[tableLen +1];memset(tableBuf, 0, tableLen+1);std::vector<unsigned short> nTmp;for (unsigned short index = 0; index < K; nTmp.push_back(pow(2, index)-1), ++index);// 表格填充pHM = HM;for (unsigned short index = 0; index < tableLen; ++index){if (std::find(nTmp.begin(), nTmp.end(), index) == nTmp.end()) { tableBuf[index] = *pHM++; }else { tableBuf[index] = '-'; }}if (HM) { delete[]HM; }HM = pHM = nullptr;// 异或运算int *kBuf = new int[K * sizeof(int)];memset(kBuf, 0, K * sizeof(int));for (unsigned short index = 0; index < K; ++index){if (index + 1 == 1){if (tableLen == 5		|| tableLen == 6)	{ kBuf[index] = JHM((int)(tableBuf[2] ^ tableBuf[4])); }									// 6else if (tableLen == 7  || tableLen == 8)	{ kBuf[index] = JHM((int)(tableBuf[2] ^ tableBuf[4] ^ tableBuf[6])); }						// 7else if (tableLen == 9  || tableLen == 10)  { kBuf[index] = JHM((int)(tableBuf[2] ^ tableBuf[4] ^ tableBuf[6] ^ tableBuf[8])); }		// 9else if (tableLen == 11 || tableLen == 12)	{ kBuf[index] = JHM((int)(tableBuf[2] ^ tableBuf[4] ^ tableBuf[6] ^ tableBuf[8] ^ tableBuf[10])); }}else if (index + 1 == 2){if (tableLen == 5)							{ kBuf[index] = JHM((int)(tableBuf[2])); }else if (tableLen == 6)						{ kBuf[index] = JHM((int)(tableBuf[5])); }													// 6else if (tableLen >= 7 && tableLen <= 9)	{ kBuf[index] = JHM((int)(tableBuf[5] ^ tableBuf[6])); }									// 7 9else if (tableLen == 10)					{ kBuf[index] = JHM((int)(tableBuf[2] ^ tableBuf[5] ^ tableBuf[6] ^ tableBuf[9])); }else if (tableLen == 11 || tableLen == 12)	{ kBuf[index] = JHM((int)(tableBuf[2] ^ tableBuf[5] ^ tableBuf[6] ^ tableBuf[9] ^ tableBuf[10])); }}else if (index + 1 == 3){if (tableLen == 5)							{ kBuf[index] = JHM((int)(tableBuf[4])); }else if (tableLen == 6)						{ kBuf[index] = JHM((int)(tableBuf[4] ^ tableBuf[5])); }									// 6else if (tableLen >=7 && tableLen <=11)		{ kBuf[index] = JHM((int)(tableBuf[4] ^ tableBuf[5] ^ tableBuf[6]));}						// 7 9else if (tableLen == 12)					{ kBuf[index] = JHM((int)(tableBuf[4] ^ tableBuf[5] ^ tableBuf[6] ^ tableBuf[11])); }}else if (index + 1 == 4){if (tableLen == 9)							{ kBuf[index] = JHM((int)(tableBuf[8]));}													// 9else if (tableLen == 10)					{ kBuf[index] = JHM((int)(tableBuf[8] ^ tableBuf[9])); }else if (tableLen == 11)					{ kBuf[index] = JHM((int)(tableBuf[8] ^ tableBuf[9] ^ tableBuf[10])); }else if (tableLen == 12)					{ kBuf[index] = JHM((int)(tableBuf[8] ^ tableBuf[9] ^ tableBuf[11] ^ tableBuf[11])); }}}// 填充完善if (K == 3 || K == 4){tableBuf[0] = (char)(kBuf[0]+48);tableBuf[1] = (char)(kBuf[1]+48);tableBuf[3] = (char)(kBuf[2]+48);if (K == 4) { tableBuf[7] = (char)(kBuf[3] + 48); }}if (kBuf) { delete[]kBuf; }kBuf = nullptr;// 翻转for (unsigned short index = 0; index < tableLen / 2; ++index){char tmp = tableBuf[index];tableBuf[index] = tableBuf[tableLen - 1 - index];tableBuf[tableLen - 1 - index] = tmp;}std::cout  << tableBuf;// 调用者需要释放return tableBuf;
}

关注

笔者 - jxd

微信公众号搜索 “码农总动员” 或 微信扫描下方二维码，了解更多你不知道的XX，O(∩_∩)O

本文来自互联网用户投稿，文章观点仅代表作者本人，不代表本站立场，不承担相关法律责任。如若转载，请注明出处。 如若内容造成侵权/违法违规/事实不符，请点击【内容举报】进行投诉反馈！