Merge pull request #201 from Bytom/v0.1

[bytom/vapor.git] / common / bit_map.go

diff --git a/common/bit_map.go b/common/bit_map.go
new file mode 100644 (file)
index 0000000..6dabaeb
--- /dev/null
+++ b/common/bit_map.go
@@ -0,0 +1,53 @@
+package common
+
+import (
+       "errors"
+)
+
+const bitLen = 32
+
+var (
+       errIndexOutOfBounds = errors.New("index out of bounds error")
+)
+
+type BitMap struct {
+       size uint32
+       arr []int32
+}
+
+func NewBitMap(size uint32) *BitMap {
+       obj := &BitMap{size: size}
+       num := (size + bitLen - 1) / bitLen
+       arr := make([]int32, num)
+       obj.arr = arr
+       return obj
+}
+
+func (b *BitMap) Set(index uint32) error {
+       if index >= b.size {
+               return errIndexOutOfBounds
+       }
+
+       arrIndex, bitIndex := index / bitLen, index % bitLen
+       b.arr[arrIndex] |= (1 << bitIndex)
+       return nil
+}
+
+func (b *BitMap) Clean(index uint32) error {
+       if index >= b.size {
+               return errIndexOutOfBounds
+       }
+
+       arrIndex, bitIndex := index / bitLen, index % bitLen
+       b.arr[arrIndex] &= (^(1 << bitIndex))
+       return nil
+}
+
+func (b *BitMap) Test(index uint32) (bool, error) {
+       if index >= b.size {
+               return false, errIndexOutOfBounds
+       }
+
+       arrIndex, bitIndex := index / bitLen, index % bitLen
+       return b.arr[arrIndex] & (1 << bitIndex) != 0, nil
+}