1 files changed, 25 insertions, 17 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/token.go b/vendor/github.com/klauspost/compress/flate/token.go
index b3df0d894..099c0ddbc 100644
--- a/vendor/github.com/klauspost/compress/flate/token.go
+++ b/vendor/github.com/klauspost/compress/flate/token.go
@@ -184,9 +184,7 @@ func (t *tokens) indexTokens(in []token) {
 	t.Reset()
 	for _, tok := range in {
 		if tok < matchType {
-			t.tokens[t.n] = tok
-			t.litHist[tok]++
-			t.n++
+			t.AddLiteral(tok.literal())
 			continue
 		}
 		t.AddMatch(uint32(tok.length()), tok.offset())
@@ -211,43 +209,53 @@ func (t *tokens) AddLiteral(lit byte) {
 	t.nLits++
 }
 
+// from https://stackoverflow.com/a/28730362
+func mFastLog2(val float32) float32 {
+	ux := int32(math.Float32bits(val))
+	log2 := (float32)(((ux >> 23) & 255) - 128)
+	ux &= -0x7f800001
+	ux += 127 << 23
+	uval := math.Float32frombits(uint32(ux))
+	log2 += ((-0.34484843)*uval+2.02466578)*uval - 0.67487759
+	return log2
+}
+
 // EstimatedBits will return an minimum size estimated by an *optimal*
 // compression of the block.
 // The size of the block
 func (t *tokens) EstimatedBits() int {
-	shannon := float64(0)
+	shannon := float32(0)
 	bits := int(0)
 	nMatches := 0
 	if t.nLits > 0 {
-		invTotal := 1.0 / float64(t.nLits)
+		invTotal := 1.0 / float32(t.nLits)
 		for _, v := range t.litHist[:] {
 			if v > 0 {
-				n := float64(v)
-				shannon += math.Ceil(-math.Log2(n*invTotal) * n)
+				n := float32(v)
+				shannon += -mFastLog2(n*invTotal) * n
 			}
 		}
 		// Just add 15 for EOB
 		shannon += 15
-		for _, v := range t.extraHist[1 : literalCount-256] {
+		for i, v := range t.extraHist[1 : literalCount-256] {
 			if v > 0 {
-				n := float64(v)
-				shannon += math.Ceil(-math.Log2(n*invTotal) * n)
-				bits += int(lengthExtraBits[v&31]) * int(v)
+				n := float32(v)
+				shannon += -mFastLog2(n*invTotal) * n
+				bits += int(lengthExtraBits[i&31]) * int(v)
 				nMatches += int(v)
 			}
 		}
 	}
 	if nMatches > 0 {
-		invTotal := 1.0 / float64(nMatches)
-		for _, v := range t.offHist[:offsetCodeCount] {
+		invTotal := 1.0 / float32(nMatches)
+		for i, v := range t.offHist[:offsetCodeCount] {
 			if v > 0 {
-				n := float64(v)
-				shannon += math.Ceil(-math.Log2(n*invTotal) * n)
-				bits += int(offsetExtraBits[v&31]) * int(n)
+				n := float32(v)
+				shannon += -mFastLog2(n*invTotal) * n
+				bits += int(offsetExtraBits[i&31]) * int(v)
 			}
 		}
 	}
-
 	return int(shannon) + bits
 }