Made changes based in reference implementation

fifo.go

@@ -106,13 +106,13 @@ func (s *fifo) getValue(ad *adapter) (value int32) {
 	s.bcount--
 
 	var level, k, tmp uint32
-	if value != 0 {
+	if value == 0 {
+		level = 0
+		k = ad.k0
+	} else {
 		level = 1
 		k = ad.k1
 		value--
-	} else {
-		level = 0
-		k = ad.k0
 	}
 	if k != 0 {
 		for s.bcount < k {
@@ -125,7 +125,7 @@ func (s *fifo) getValue(ad *adapter) (value int32) {
 		s.bcount -= k
 		s.bcache &= bitMask[s.bcount]
 	}
-	if level != 0 {
+	if level == 1 {
 		ad.sum1 += uint32(value) - (ad.sum1 >> 4)
 		if ad.k1 > 0 && ad.sum1 < shift16[ad.k1] {
 			ad.k1--