40 lines
844 B
Go
40 lines
844 B
Go
|
package structs
|
||
|
|
|
||
|
|
import "fmt"
|
||
|
|
|
||
|
|
// Bitmap is a simple uncompressed bitmap
|
||
|
|
type Bitmap []byte
|
||
|
|
|
||
|
|
// NewBitmap returns a bitmap with up to size indexes
|
||
|
|
func NewBitmap(size int) (Bitmap, error) {
|
||
|
|
if size <= 0 {
|
||
|
|
return nil, fmt.Errorf("bitmap must be positive size")
|
||
|
|
}
|
||
|
|
if size&7 != 0 {
|
||
|
|
return nil, fmt.Errorf("bitmap must be byte aligned")
|
||
|
|
}
|
||
|
|
b := make([]byte, size>>3)
|
||
|
|
return Bitmap(b), nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// Set is used to set the given index of the bitmap
|
||
|
|
func (b Bitmap) Set(idx uint) {
|
||
|
|
bucket := idx >> 3
|
||
|
|
mask := byte(1 << (idx & 7))
|
||
|
|
b[bucket] |= mask
|
||
|
|
}
|
||
|
|
|
||
|
|
// Check is used to check the given index of the bitmap
|
||
|
|
func (b Bitmap) Check(idx uint) bool {
|
||
|
|
bucket := idx >> 3
|
||
|
|
mask := byte(1 << (idx & 7))
|
||
|
|
return (b[bucket] & mask) != 0
|
||
|
|
}
|
||
|
|
|
||
|
|
// Clear is used to efficiently clear the bitmap
|
||
|
|
func (b Bitmap) Clear() {
|
||
|
|
for i := range b {
|
||
|
|
b[i] = 0
|
||
|
|
}
|
||
|
|
}
|