encoding

README

Encoding

This is a set of integer compression algorithms implemented in Go. It is an (incomplete) port of the JavaFastPFOR by Dr. Daniel Lemire.

For more detailed benchmark results please see http://zhen.org/blog/benchmarking-integer-compression-in-go/

Documentation

Index

• func CeilBy(value, factor int) int
• func Delta(in, out []int32, offset int32)
• func DeltaMaxBits(initoffset int32, buf []int32) int32
• func FloorBy(value, factor int) int
• func InverseDelta(in, out []int32, offset int32)
• func InverseZigZagDelta(in, out []int32)
• func LeadingBitPosition(x uint32) int32
• func MaxBits(buf []int32) int32
• func PrintInt32sInBits(buf []int32)
• func UnrolledDelta128(in, out []int32, offset int32)
• func UnrolledInverseDelta128(in, out []int32, offset int32)
• func UnrolledLeadingBitFrequency128(in, freqs []int32)
• func ZigZagDelta(in, out []int32)
• type Integer

Functions

func CeilBy

func CeilBy(value, factor int) int

func Delta

func Delta(in, out []int32, offset int32)

func DeltaMaxBits

func DeltaMaxBits(initoffset int32, buf []int32) int32

func FloorBy

func FloorBy(value, factor int) int

func InverseDelta

func InverseDelta(in, out []int32, offset int32)

func InverseZigZagDelta

func InverseZigZagDelta(in, out []int32)

func LeadingBitPosition

func LeadingBitPosition(x uint32) int32

func MaxBits

func MaxBits(buf []int32) int32

func PrintInt32sInBits

func PrintInt32sInBits(buf []int32)

func UnrolledDelta128

func UnrolledDelta128(in, out []int32, offset int32)

The following are unrolled versions, but they are probably slower due to range checks

func UnrolledInverseDelta128

func UnrolledInverseDelta128(in, out []int32, offset int32)

func UnrolledLeadingBitFrequency128

func UnrolledLeadingBitFrequency128(in, freqs []int32)

func ZigZagDelta

func ZigZagDelta(in, out []int32)

https://developers.google.com/protocol-buffers/docs/encoding#types

Types

type Integer

type Integer interface {
	// Compress data from an array to another array.
	//
	// Both inpos and outpos are modified to represent how much data was read and written to
	// if 12 ints (inlength = 12) are compressed to 3 ints, then inpos will be incremented by 12
	// while outpos will be incremented by 3 we use IntWrapper to pass the values by reference.
	// @param in  input array
	// @param inpos location in the input array
	// @param inlength how many integers to compress
	// @param out output array
	//* @param outpos  where to write in the output array
	Compress(in []int32, inpos *cursor.Cursor, inlength int, out []int32, outpos *cursor.Cursor) error

	/**
	 * Uncompress data from an array to another array.
	 *
	 * Both inpos and outpos parameters are modified to indicate new positions after read/write.
	 *
	 * @param in array containing data in compressed form
	 * @param inpos where to start reading in the array
	 * @param inlength length of the compressed data (ignored by some schemes)
	 * @param out array where to write the compressed output
	 * @param outpos where to write the compressed output in out
	 */
	Uncompress(in []int32, inpos *cursor.Cursor, inlength int, out []int32, outpos *cursor.Cursor) error
}