Package org.apache.hadoop.io.erasurecode.rawcoder.util

Class GF256

java.lang.Object

org.apache.hadoop.io.erasurecode.rawcoder.util.GF256

@Private
public final class GF256
extends Object

A GaloisField utility class only caring of 256 fields for efficiency. Some of the codes are borrowed from ISA-L implementation (C or ASM codes).

Method Summary

Modifier and Type	Method	Description
static byte[]	gfBase()
static byte	gfInv(byte a)
static void	gfInvertMatrix(byte[] inMatrix, byte[] outMatrix, int n)	Invert a matrix assuming it's invertible.
static byte[]	gfLogBase()
static byte	gfMul(byte a, byte b)
static byte[][]	gfMulTab()	Get the big GF multiply table so utilize it efficiently.
static void	gfVectMulInit(byte c, byte[] tbl, int offset)	Ported from Intel ISA-L library.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

gfBase

public static byte[] gfBase()

gfLogBase

public static byte[] gfLogBase()

gfMulTab

public static byte[][] gfMulTab()

Get the big GF multiply table so utilize it efficiently.

Returns:

the big GF multiply table

gfMul

public static byte gfMul(byte a,
 byte b)

gfInv

public static byte gfInv(byte a)

gfInvertMatrix

public static void gfInvertMatrix(byte[] inMatrix,
 byte[] outMatrix,
 int n)

Invert a matrix assuming it's invertible. Ported from Intel ISA-L library.

Parameters:

inMatrix - inMatrix.

outMatrix - outMatrix.

n - n

gfVectMulInit

public static void gfVectMulInit(byte c,
 byte[] tbl,
 int offset)

Ported from Intel ISA-L library. Calculates const table gftbl in GF(2^8) from single input A gftbl(A) = {A{00}, A{01}, A{02}, ... , A{0f} }, {A{00}, A{10}, A{20}, ... , A{f0} } -- from ISA-L implementation.

Parameters:

c - c.

tbl - tbl.

offset - offset.