Displaying 1 to 8 from 8 results

Vc - SIMD Vector Classes for C++

  •    C++

Recent generations of CPUs, and GPUs in particular, require data-parallel codes for full efficiency. Data parallelism requires that the same sequence of operations is applied to different input data. CPUs and GPUs can thus reduce the necessary hardware for instruction decoding and scheduling in favor of more arithmetic and logic units, which execute the same instructions synchronously. On CPU architectures this is implemented via SIMD registers and instructions. A single SIMD register can store N values and a single SIMD instruction can execute N operations on those values. On GPU architectures N threads run in perfect sync, fed by a single instruction decoder/scheduler. Each thread has local memory and a given index to calculate the offsets in memory for loads and stores. Current C++ compilers can do automatic transformation of scalar codes to SIMD instructions (auto-vectorization). However, the compiler must reconstruct an intrinsic property of the algorithm that was lost when the developer wrote a purely scalar implementation in C++. Consequently, C++ compilers cannot vectorize any given code to its most efficient data-parallel variant. Especially larger data-parallel loops, spanning over multiple functions or even translation units, will often not be transformed into efficient SIMD code.

xsimd - Modern, portable C++ wrappers for SIMD intrinsics and parallelized, optimized math implementations

  •    C++

SIMD (Single Instruction, Multiple Data) is a feature of microprocessors that has been available for many years. SIMD instructions perform a single operation on a batch of values at once, and thus provide a way to significantly accelerate code execution. However, these instructions differ between microprocessor vendors and compilers. xsimd provides a unified means for using these features for library authors. Namely, it enables manipulation of batches of numbers with the same arithmetic operators as for single values. It also provides accelerated implementation of common mathematical functions operating on batches.

dictionary - High-performance dictionary coding

  •    C++

Suppose you want to compress a large array of values with (relatively) few distinct values. For example, maybe you have 16 distinct 64-bit values. Only four bits are needed to store a value in the range [0,16) using binary packing, so if you have long arrays, it is possible to save 60 bits per value (compress the data by a factor of 16).We consider the following (simple) form of dictionary coding. We have a dictionary of 64-bit values (could be pointers) stored in an array. In the compression phase, we convert the values to indexes and binary pack them. In the decompression phase, we try to recover the dictionary-coded values as fast as possible.

FastDifferentialCoding - Fast differential coding functions (using SIMD instructions)

  •    C

These functions compute fast successive differences, and recover the original values from the fast successive differences (i.e., they compute a prefix sum) using fast SIMD instructions.They can be useful as part of compressed index.




SIMDCompressionAndIntersection - A C++ library to compress and intersect sorted lists of integers using SIMD instructions

  •    C++

As the name suggests, this is a C/C++ library for fast compression and intersection of lists of sorted integers using SIMD instructions. The library focuses on innovative techniques and very fast schemes, with particular attention to differential coding. It introduces new SIMD intersections schemes such as SIMD Galloping.This library can decode at least 4 billions of compressed integers per second on most desktop or laptop processors. That is, it can decompress data at a rate of 15 GB/s. This is significantly faster than generic codecs like gzip, LZO, Snappy or LZ4.

SIMDxorshift - Fast random number generators: Vectorized (SIMD) version of xorshift128+

  •    C

Xorshift are a family of pseudo-random number generators (RNG) invented by Marsaglia.We present a vectorized version of xorshift128+, a popular random-number generator part of this family. It is written in C. The implementation uses Intel's SIMD instructions and is based on Vigna's original (pure C) implementation.