-
Notifications
You must be signed in to change notification settings - Fork 0
/
bitmap.go
147 lines (126 loc) · 2.86 KB
/
bitmap.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
package util
import (
"encoding/json"
"unsafe"
)
// For this 'Bitmap', every single bit is born to be 0.
type Bitmap struct {
val []uint64
length int
}
var bitmapStructMemUsage int
func init() {
bitmapStructMemUsage = int(unsafe.Sizeof(Bitmap{}))
}
func NewBitmap() *Bitmap {
return &Bitmap{}
}
// NewBitmapWithCap cap's unit is [bit]
func NewBitmapWithCap(cap uint64) *Bitmap {
return &Bitmap{
val: make([]uint64, 0, (cap>>6)+1),
}
}
func getSegAndOffsetByNum(num int) (seg int, offset uint) {
seg = num >> 6 // num/64
offset = uint(num - (seg << 6)) // num%64
return
}
func (bitmap *Bitmap) getBit(seg int, offset uint) uint64 {
return bitmap.val[seg] & (1 << offset)
}
func (bitmap *Bitmap) setBit(seg int, offset uint) {
bitmap.val[seg] |= 1 << offset
bitmap.length++
}
func (bitmap *Bitmap) clearBit(seg int, offset uint) {
bitmap.val[seg] -= 1 << offset
bitmap.length--
}
func (bitmap *Bitmap) Has(num int) bool {
seg, offset := getSegAndOffsetByNum(num)
return seg < len(bitmap.val) && (bitmap.getBit(seg, offset)) != 0
}
func (bitmap *Bitmap) Set(num int) {
seg, offset := getSegAndOffsetByNum(num)
// expand capacity
for seg >= len(bitmap.val) {
bitmap.val = append(bitmap.val, 0)
}
// check if 'num' has already been in the bitmap
if bitmap.getBit(seg, offset) == 0 {
bitmap.setBit(seg, offset)
}
}
func (bitmap *Bitmap) Clear(num int) {
seg, offset := getSegAndOffsetByNum(num)
if seg >= len(bitmap.val) || bitmap.getBit(seg, offset) == 0 {
return
}
bitmap.clearBit(seg, offset)
}
func (bitmap *Bitmap) Len() int {
return bitmap.length
}
func (bitmap *Bitmap) Cap() int {
return len(bitmap.val) << 6
}
func hammingWeight(n uint64) int {
res := 0
for n != 0 {
n = n & (n - 1)
res++
}
return res
}
func (bitmap *Bitmap) BitCount(start int, end int) int {
if start < 0 || end < 0 || start >= bitmap.Cap() {
return -1
}
if end > bitmap.Cap() {
end = bitmap.Cap()
}
startSeg, startOffset := getSegAndOffsetByNum(start)
endSeg, endOffset := getSegAndOffsetByNum(end)
count := 0
for i := startSeg; i <= endSeg; i++ {
count += hammingWeight(bitmap.val[i])
}
// the segment 'start' at
for i := uint(0); i < startOffset; i++ {
if bitmap.getBit(startSeg, i) != 0 {
count--
}
}
// the segment 'end' at
for i := endOffset; i < 64; i++ {
if bitmap.getBit(endSeg, i) != 0 {
count--
}
}
return count
}
func (bitmap *Bitmap) Value() []uint64 {
arr := make([]uint64, bitmap.length)
index := 0
for seg, v := range bitmap.val {
if v == 0 {
continue
}
// offset
for j := uint(0); j < 64; j++ {
if v&(1<<j) != 0 {
arr[index] = uint64(64*uint(seg) + j)
index++
}
}
}
return arr
}
func (bitmap *Bitmap) String() string {
bytes, _ := json.Marshal(bitmap.Value())
return string(bytes)
}
func (bitmap *Bitmap) MemoryUsage() int {
return (len(bitmap.val) << 3) + bitmapStructMemUsage
}