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- package binary
-
- import (
- "fmt"
- "math/rand"
- "strings"
-
- . "github.com/tendermint/tendermint/common"
- )
-
- // Not goroutine safe
- type BitArray struct {
- Bits uint // NOTE: persisted via reflect, must be exported
- Elems []uint64 // NOTE: persisted via reflect, must be exported
- }
-
- func NewBitArray(bits uint) BitArray {
- return BitArray{bits, make([]uint64, (bits+63)/64)}
- }
-
- func (bA BitArray) Size() uint {
- return bA.Bits
- }
-
- func (bA BitArray) IsZero() bool {
- return bA.Bits == 0
- }
-
- // NOTE: behavior is undefined if i >= bA.Bits
- func (bA BitArray) GetIndex(i uint) bool {
- if i >= bA.Bits {
- return false
- }
- return bA.Elems[i/64]&uint64(1<<(i%64)) > 0
- }
-
- // NOTE: behavior is undefined if i >= bA.Bits
- func (bA BitArray) SetIndex(i uint, v bool) bool {
- if i >= bA.Bits {
- return false
- }
- if v {
- bA.Elems[i/64] |= uint64(1 << (i % 64))
- } else {
- bA.Elems[i/64] &= ^uint64(1 << (i % 64))
- }
- return true
- }
-
- func (bA BitArray) Copy() BitArray {
- c := make([]uint64, len(bA.Elems))
- copy(c, bA.Elems)
- return BitArray{bA.Bits, c}
- }
-
- func (bA BitArray) copyBits(bits uint) BitArray {
- c := make([]uint64, (bits+63)/64)
- copy(c, bA.Elems)
- return BitArray{bits, c}
- }
-
- // Returns a BitArray of larger bits size.
- func (bA BitArray) Or(o BitArray) BitArray {
- c := bA.copyBits(MaxUint(bA.Bits, o.Bits))
- for i := 0; i < len(c.Elems); i++ {
- c.Elems[i] |= o.Elems[i]
- }
- return c
- }
-
- // Returns a BitArray of smaller bit size.
- func (bA BitArray) And(o BitArray) BitArray {
- c := bA.copyBits(MinUint(bA.Bits, o.Bits))
- for i := 0; i < len(c.Elems); i++ {
- c.Elems[i] &= o.Elems[i]
- }
- return c
- }
-
- func (bA BitArray) Not() BitArray {
- c := bA.Copy()
- for i := 0; i < len(c.Elems); i++ {
- c.Elems[i] = ^c.Elems[i]
- }
- return c
- }
-
- func (bA BitArray) Sub(o BitArray) BitArray {
- if bA.Bits > o.Bits {
- c := bA.Copy()
- for i := 0; i < len(o.Elems)-1; i++ {
- c.Elems[i] &= ^c.Elems[i]
- }
- i := uint(len(o.Elems) - 1)
- if i >= 0 {
- for idx := i * 64; idx < o.Bits; idx++ {
- c.SetIndex(idx, c.GetIndex(idx) && !o.GetIndex(idx))
- }
- }
- return c
- } else {
- return bA.And(o.Not())
- }
- }
-
- func (bA BitArray) PickRandom() (uint, bool) {
- length := len(bA.Elems)
- if length == 0 {
- return 0, false
- }
- randElemStart := rand.Intn(length)
- for i := 0; i < length; i++ {
- elemIdx := ((i + randElemStart) % length)
- if elemIdx < length-1 {
- if bA.Elems[elemIdx] > 0 {
- randBitStart := rand.Intn(64)
- for j := 0; j < 64; j++ {
- bitIdx := ((j + randBitStart) % 64)
- if (bA.Elems[elemIdx] & (1 << uint(bitIdx))) > 0 {
- return 64*uint(elemIdx) + uint(bitIdx), true
- }
- }
- panic("should not happen")
- }
- } else {
- // Special case for last elem, to ignore straggler bits
- elemBits := int(bA.Bits) % 64
- if elemBits == 0 {
- elemBits = 64
- }
- randBitStart := rand.Intn(elemBits)
- for j := 0; j < elemBits; j++ {
- bitIdx := ((j + randBitStart) % elemBits)
- if (bA.Elems[elemIdx] & (1 << uint(bitIdx))) > 0 {
- return 64*uint(elemIdx) + uint(bitIdx), true
- }
- }
- }
- }
- return 0, false
- }
-
- func (bA BitArray) String() string {
- return bA.StringIndented("")
- }
-
- func (bA BitArray) StringIndented(indent string) string {
- lines := []string{}
- bits := ""
- for i := uint(0); i < bA.Bits; i++ {
- if bA.GetIndex(i) {
- bits += "X"
- } else {
- bits += "_"
- }
- if i%100 == 99 {
- lines = append(lines, bits)
- bits = ""
- }
- if i%10 == 9 {
- bits += " "
- }
- if i%50 == 49 {
- bits += " "
- }
- }
- if len(bits) > 0 {
- lines = append(lines, bits)
- }
- return fmt.Sprintf("BA{%v:%v}", bA.Bits, strings.Join(lines, indent))
- }
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