方法CountSetBits返回指定位字段中设置为 1 的位数。 语法 C++复制 DWORDCountSetBits(constDWORD Field ); 参数 字段 将位字段指定为DWORD值。 返回值 返回设置为 1 的位数。 要求 要求值 标头 Winutil.h (包括 Streams.h) 库 Strmbase.lib (零售版本) ; ...
我很好奇,由BitTwiddling Hacks指出,与简单的Lookup Table方法相比,该算法的性能要好得多...现在,我想,也许我的一点研究对其他人也很有趣... PS:并行计数算法大约是35在我的计算机上平均比simpel LUT解决方案快%。 这也很好地显示了与人脑兼容的解决方案与二进制机器最佳解决方案的不同之处:-) PS:请参见代码...
To count set bits by lookup table we construct a static table, lookup_t having 256 entries giving the number of set bits in each possible byte value (e.g. 0 = 0, 1 = 1, 2 = 1, 3 = 2, and so on). Then use this table to find the number of ones in each byte of the ...
unsigned int v; // count the number of bits set in 32-bit value v unsigned int c; // c is the total bits set in v // Option 1: c = BitsSetTable256[v & 0xff] + BitsSetTable256[(v >> 8) & 0xff] + BitsSetTable256[(v >> 16) & 0xff] + BitsSetTable256[v >> 24]...
如果要计算一个整形中的位数有多少位被置位,我们的第一想法就是循环查找。现在我们可以参考:http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel unsignedintbits_counter_v4(unsignedintx) {//count bits of each 2-bit chunkx = x - ((x >>1) &0x55555555);//count bits of ea...
验证WavePrefixCountBits DXIL 指令。 测试详细信息 展开表 规范 Device.Graphics.WDDM22.AdapterRender.D3D12.DXIL.WaveOps.CoreRequirement 平台 Windows 10,客户端版本 (x86) Windows 10,客户端版本 (x64) Windows Server 2016 (x64) Windows 10,客户端版本 (Arm64) Windows 10,移动版本 (Arm) Windows 10...
The result of the compressor tree circuit is a binary value representing a number related to the operation performed (the number of set bits for PopCount, or the bit position of the first set bit encountered by scanning the input word).Ramanarayanan, Rajaraman...
运行 AI代码解释 mysql>SELECTcate,BIT_AND(number),BIT_OR(number),BIT_XOR(number)FROMtestGROUPBYcate;+---+---+---+---+|cate|BIT_AND(number)|BIT_OR(number)|BIT_XOR(number)|+---+---+---+---+|a|100|111|101||b|0|11|10|+---+---+---+---...
<<" set bit\n";// Function tocountthe// number of set bits in b2intresult2 = b2.count();cout<< b2 <<" has "<< result2 <<" set bit";return0; } 输出: 1100 has 2 set bit 001000 has 1 set bit 示例2: // CPP program to illustrate the// bitset::count() function// when...
http://www.varlena.com/GeneralBits/120.php 5.通过扩展插件统计 我们还可以通过pgstattuple这个扩展实现,这种能得到真实的结果,但效率比较慢: 1)创建扩展: akendb=# create extension pgstattuple; CREATE EXTENSION akendb=# \dx List of installed extensions ...