github.com/cryptoecc/eth-ecc@v0.0.3/consensus/ethash/LDPCDecoder.go

package ethash

import (
	"math"
)

//OptimizedDecoding return hashVector, outputWord, LRrtl and It is 20% faster than previous decoding function when they use same nonce
//percentage can be changed because of random nonce
func OptimizedDecoding(parameters Parameters, hashVector []int, H, rowInCol, colInRow [][]int) ([]int, []int, [][]float64) {
	outputWord := make([]int, parameters.n)
	LRqtl := make([][]float64, parameters.n)
	LRrtl := make([][]float64, parameters.n)
	LRft := make([]float64, parameters.n)

	for i := 0; i < parameters.n; i++ {
		LRqtl[i] = make([]float64, parameters.m)
		LRrtl[i] = make([]float64, parameters.m)
		LRft[i] = math.Log((1-crossErr)/crossErr) * float64((hashVector[i]*2 - 1))
	}
	LRpt := make([]float64, parameters.n)

	for ind := 1; ind <= maxIter; ind++ {
		for t := 0; t < parameters.n; t++ {
			temp3 := 0.0

			for mp := 0; mp < parameters.wc; mp++ {
				temp3 = infinityTest(temp3 + LRrtl[t][rowInCol[mp][t]])
			}
			for m := 0; m < parameters.wc; m++ {
				temp4 := temp3
				temp4 = infinityTest(temp4 - LRrtl[t][rowInCol[m][t]])
				LRqtl[t][rowInCol[m][t]] = infinityTest(LRft[t] + temp4)
			}
		}

		for k := 0; k < parameters.wr; k++ {
			for l := 0; l < parameters.wr; l++ {
				temp3 := 0.0
				sign := 1.0
				tempSign := 0.0
				for m := 0; m < parameters.wr; m++ {
					if m != l {
						temp3 = temp3 + funcF(math.Abs(LRqtl[colInRow[m][k]][k]))
						if LRqtl[colInRow[m][k]][k] > 0.0 {
							tempSign = 1.0
						} else {
							tempSign = -1.0
						}
						sign = sign * tempSign
					}
				}
				magnitude := funcF(temp3)
				LRrtl[colInRow[l][k]][k] = infinityTest(sign * magnitude)
			}
		}

		for t := 0; t < parameters.n; t++ {
			LRpt[t] = infinityTest(LRft[t])
			for k := 0; k < parameters.wc; k++ {
				LRpt[t] += LRrtl[t][rowInCol[k][t]]
				LRpt[t] = infinityTest(LRpt[t])
			}

			if LRpt[t] >= 0 {
				outputWord[t] = 1
			} else {
				outputWord[t] = 0
			}
		}
	}

	return hashVector, outputWord, LRrtl
}