Notes on computers, programming and all the stuff

Base64 decoding could also be vectorized, although the speedup is not very impressive, merely 35%. Read more ...

An SSE code is more than 2 times faster on Core i7, and around 70% faster on Core i5. Read more...

The conversion to string could be 15 times faster than sprintf . Read more...

Although base64 encoding is a very basic algorithm, it could be sped up a little (25% sounds good?) Read more...

The problem is defined as follows: a set of features is saved using bit-sets (usually large), and there is a list/map/whatever of sets conta...

Interesting article by Radford M. Neal : I present two new methods for exactly summing a set of floating-point numbers, and then correctl...

Another interesting paper : Our experimental results currently put our prototype implementation at about twice as fast as the Boost impl...

Recently I've checked different methods to convert numbers to binary representation , including use of new PDEP instruction from BMI2 e...

Nearly 50% faster than naive version for large data sets. Discovered by accident. :)

The problem: there is a ordered dictionary containing only unique keys. Dictionary is read only, and keys are 32-bit (SSE) or 64-bit (AVX2...

Informal specification: __m128i mask_lower(const unsigned n) { assert(n < 16); switch (n) { case 0: return {0x00, ...

Milo Yip has compared different itoa and dtoa implementations on Core i7, including my itoa algorithm 2 , that use SSE2 instructions. R...

Interpolation search revisited -- theoretical complexity of interpolation search is very promising, but...

Conversion numbers to hexadecimal representation - SWAR, plain SSE, and draft of BMI2 implementation. Article SSSE3: printing hex values...

New article Conversion numbers to binary representation — SIMD & SWAR versions. Few years ago I've described an MMX variant of SI...

SSE instruction PMOVMSKB gathers all most significant bits from bytes and stores them as a single 16-bit value; similar action is performed...

Very interesting idea: Asymmetric numeral systems: entropy coding combining speed of Huffman coding with compression rate of arithmetic co...

Rabin-Karp algorithm uses a weak hash function to locate possible substring positions. This modification uses merely equality of first and...

Fast calculate ceil(log10(x)) of some unsigned number is described on Bit Twiddling Hacks , this text show the SIMD solution for 32-bit numb...

The description of Determine if a word has a zero byte from "Bit Twiddling Hacks" says about haszero(v) : " the result is th...