/* Write as a d-gaps list */
func (bv *BitVector) writeClearedDgaps(output store.IndexOutput) error {
err := store.Stream(output).
WriteInt(-1). // mark using d-gaps
WriteInt(int32(bv.size)).
WriteInt(int32(bv.Count())).
Close()
if err != nil {
return err
}
last, numCleared := 0, bv.size-bv.Count()
for i, v := range bv.bits {
if v == byte(0xff) {
continue
}
err = output.WriteVInt(int32(i - last))
if err == nil {
err = output.WriteByte(v)
}
if err != nil {
return err
}
last = i
numCleared -= (8 - util.BitCount(v))
assert(numCleared >= 0 ||
i == len(bv.bits)-1 && numCleared == -(8-(bv.size&7)))
if numCleared <= 0 {
break
}
}
return nil
}
/*
Returns the total number of bits in this vector. This is efficiently
computed and cached, so that, if the vector is not changed, no
recomputation is done for repeated calls.
*/
func (bv *BitVector) Count() int {
// if the vector has been modified
if bv.count == -1 {
c := 0
for _, v := range bv.bits {
c += util.BitCount(v) // sum bits per byte
}
bv.count = c
}
assert2(bv.count <= bv.size, "count=%v size=%v", bv.count, bv.size)
return bv.count
}