WebJan 31, 2012 · As far as I'm aware, there is no MSIL instruction for this "find first set" operation. The simplest thing to do is write your own C++ native DLL that exports a … WebSep 26, 2013 · See if your compiler supports the X86 bit scan forward instruction as an intrinsic function. For microsoft, this is _bitscanforward() and _bitscanforward64() (if in 64 bit mode). If not, and speed is important except for initialization, you could use a char array of size 65536, which is indexed by a 16 bit value where each char contains the ...
Bit scanning equivalencies The ryg blog
WebJan 2, 2024 · it will include all SSE/AVX headers which are enabled according to compiler switches like -march=haswell or just -march=native. Additionally some x86 specific instructions like bswap or ror become available as intrinsics. The MSVC equivalent of this header . If you just want portable SIMD, use #include . WebJun 20, 2014 · LUT[N % k] with k-position LUT: one modulo, one lookup (k=37 for 32-bit and 67 for 64-bit numbers) In practice, #1 is great with small n , #2 may be fastest on certain hardware (something without fast multiply), but the code looks ugly. #3 probably never beats DeBruijn on a real machine, but it has fewer operations. opening to horseland 2010 dvd
BSF -- Bit Scan Forward - Massachusetts Institute of …
WebBit Instructions. Bit Scan Forward (bsf) bsf{wl} r/m[16 32], reg[16 32] Operation (r/m = 0) 0 -> ZF (r/m [ne ] 0) 0 -> ZF. Description. bsf scans the bits, starting at bit 0, in the … WebOct 21, 2024 · The TZCNT (Count the Number of Trailing Zero Bits) instruction is often described as doing "basically the same thing as" or as being "an extension of" the BSF (Bit Scan Forward) instruction. There are two differences between them: BSF is undefined for an input of 0 (in practice it leaves the output register unmodified), whereas TZCNT is … WebBSF - Bit Scan Forward (386+) Usage: BSF dest,src Modifies flags: ZF Scans source operand for first bit set. Sets ZF if a bit is found set and loads the destination with an … opening to hooray for thomas vhs