chunkenc: Bugfix and naming tweaks
@@ -388,41 +388,44 @@ func (it *xorIterator) readValue() bool {
func xorWrite(
b *bstream,
- current, previous float64,
+ newValue, currentValue float64,
currentLeading, currentTrailing uint8,
) (newLeading, newTrailing uint8) {
- delta := math.Float64bits(current) ^ math.Float64bits(previous)
+ delta := math.Float64bits(newValue) ^ math.Float64bits(currentValue)
if delta == 0 {
b.writeBit(zero)
- return
+ return currentLeading, currentTrailing
}
b.writeBit(one)
- leading := uint8(bits.LeadingZeros64(delta))
- trailing := uint8(bits.TrailingZeros64(delta))
+ newLeading = uint8(bits.LeadingZeros64(delta))
+ newTrailing = uint8(bits.TrailingZeros64(delta))
// Clamp number of leading zeros to avoid overflow when encoding.
- if leading >= 32 {
- leading = 31
+ if newLeading >= 32 {
+ newLeading = 31
}
- if currentLeading != 0xff && leading >= currentLeading && trailing >= currentTrailing {
+ if currentLeading != 0xff && newLeading >= currentLeading && newTrailing >= currentTrailing {
+ // In this case, we stick with the current leading/trailing.
b.writeBit(zero)
b.writeBits(delta>>currentTrailing, 64-int(currentLeading)-int(currentTrailing))
return currentLeading, currentTrailing
}
b.writeBit(one)
- b.writeBits(uint64(leading), 5)
-
- // Note that if leading == trailing == 0, then sigbits == 64. But that value doesn't actually fit into the 6 bits we have.
- // Luckily, we never need to encode 0 significant bits, since that would put us in the other case (vdelta == 0).
- // So instead we write out a 0 and adjust it back to 64 on unpacking.
- sigbits := 64 - leading - trailing
+ b.writeBits(uint64(newLeading), 5)
+
+ // Note that if newLeading == newTrailing == 0, then sigbits == 64. But
+ // that value doesn't actually fit into the 6 bits we have. Luckily, we
+ // never need to encode 0 significant bits, since that would put us in
+ // the other case (vdelta == 0). So instead we write out a 0 and adjust
+ // it back to 64 on unpacking.
+ sigbits := 64 - newLeading - newTrailing
b.writeBits(uint64(sigbits), 6)
- b.writeBits(delta>>trailing, int(sigbits))
- return leading, trailing
+ b.writeBits(delta>>newTrailing, int(sigbits))
+ return
}
func xorRead(
