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package tensor
// BitMap is a very simple bitmap. It only supports Set, IsSet and Clear methods. It's mostly used for tracking which element has been set
type BitMap struct {
n []uint64
max int
}
// NewBitMap creates a new BitMap.
func NewBitMap(size int) *BitMap {
q, r := divmod(size, 64)
if r > 0 {
q++
}
return &BitMap{
n: make([]uint64, q),
max: size,
}
}
// Set sets the ith bit of the bit map to 1. It panics if i is greater or equal to the defined max
func (bm *BitMap) Set(i int) {
if i >= bm.max || i < 0 {
panic("Index out of range")
}
block, pos := divmod(i, 64)
bm.n[block] |= uint64(1) << uint64(pos)
}
// IsSet returns true if the ith bit is set. It panics if the i is greater or equal to the defined max
func (bm *BitMap) IsSet(i int) bool {
if i >= bm.max || i < 0 {
panic("Index out of range")
}
block, pos := divmod(i, 64)
return bm.n[block]>>uint64(pos)&uint64(1) == uint64(1)
}
// Clear clears the ith bit. It panics if i is greater or equal to the defined max
func (bm *BitMap) Clear(i int) {
if i >= bm.max || i < 0 {
panic("Index out of range")
}
block, pos := divmod(i, 64)
bm.n[block] &= ^(uint64(1) << uint64(pos))
}
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