github.com/benz9527/xboot@v0.0.0-20240504061247-c23f15593274/lib/bits/bitmap.go (about)

     1  package bits
     2  
     3  import "bytes"
     4  
     5  type Bitmap interface {
     6  	SetBit(offset uint64) bool
     7  	UnsetBit(offset uint64) bool
     8  	GetBit(offset uint64) bool
     9  	GetBits() []byte
    10  	EqualTo(bm Bitmap) bool
    11  	Purge()
    12  }
    13  
    14  const (
    15  	maxBitMapSize = 1 << 32
    16  )
    17  
    18  type x32Bitmap struct {
    19  	bits []byte
    20  	size uint64
    21  }
    22  
    23  func NewX32Bitmap(size uint64) Bitmap {
    24  	if size <= 0 || size > maxBitMapSize {
    25  		size = maxBitMapSize
    26  	}
    27  	if remainder := size & 0x07; remainder != 0 {
    28  		size = size + (8 - remainder)
    29  	}
    30  	return &x32Bitmap{
    31  		bits: make([]byte, size>>3),
    32  		size: size - 1,
    33  	}
    34  }
    35  
    36  func (bm *x32Bitmap) SetBit(offset uint64) bool {
    37  	idx, pos := offset>>3, offset&0x07
    38  	if bm.size < offset {
    39  		return false
    40  	}
    41  	bm.bits[idx] |= 1 << pos
    42  	return true
    43  }
    44  
    45  func (bm *x32Bitmap) UnsetBit(offset uint64) bool {
    46  	idx, pos := offset>>3, offset&0x07
    47  	if bm.size < offset {
    48  		return false
    49  	}
    50  	bm.bits[idx] &= ^(1 << pos) // &^=
    51  	return true
    52  }
    53  
    54  func (bm *x32Bitmap) GetBit(offset uint64) bool {
    55  	idx, pos := offset>>3, offset&0x07
    56  	if bm.size < offset {
    57  		return false
    58  	}
    59  	return bm.bits[idx]>>pos != 0
    60  }
    61  
    62  func (bm *x32Bitmap) GetBits() []byte {
    63  	return bm.bits
    64  }
    65  
    66  func (bm *x32Bitmap) EqualTo(that Bitmap) bool {
    67  	return bytes.Compare(bm.GetBits(), that.GetBits()) == 0
    68  }
    69  
    70  func (bm *x32Bitmap) Purge() {
    71  	clear(bm.bits)
    72  }