Add BitArray.Bytes()

bit_array.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"encoding/binary"
 	"fmt"
 	"math/rand"
 	"strings"
@@ -273,3 +274,17 @@ func (bA *BitArray) stringIndented(indent string) string {
 	}
 	return fmt.Sprintf("BA{%v:%v}", bA.Bits, strings.Join(lines, indent))
 }
+
+func (bA *BitArray) Bytes() []byte {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	numBytes := (bA.Bits + 7) / 8
+	bytes := make([]byte, numBytes)
+	for i := 0; i < len(bA.Elems); i++ {
+		elemBytes := [8]byte{}
+		binary.LittleEndian.PutUint64(elemBytes[:], bA.Elems[i])
+		copy(bytes[i*8:], elemBytes[:])
+	}
+	return bytes
+}

bit_array_test.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"bytes"
 	"testing"
 )
 
@@ -118,3 +119,32 @@ func TestPickRandom(t *testing.T) {
 		}
 	}
 }
+
+func TestBytes(t *testing.T) {
+	bA := NewBitArray(4)
+	bA.SetIndex(0, true)
+	check := func(bA *BitArray, bz []byte) {
+		if !bytes.Equal(bA.Bytes(), bz) {
+			panic(Fmt("Expected %X but got %X", bz, bA.Bytes()))
+		}
+	}
+	check(bA, []byte{0x01})
+	bA.SetIndex(3, true)
+	check(bA, []byte{0x09})
+
+	bA = NewBitArray(9)
+	check(bA, []byte{0x00, 0x00})
+	bA.SetIndex(7, true)
+	check(bA, []byte{0x80, 0x00})
+	bA.SetIndex(8, true)
+	check(bA, []byte{0x80, 0x01})
+
+	bA = NewBitArray(16)
+	check(bA, []byte{0x00, 0x00})
+	bA.SetIndex(7, true)
+	check(bA, []byte{0x80, 0x00})
+	bA.SetIndex(8, true)
+	check(bA, []byte{0x80, 0x01})
+	bA.SetIndex(9, true)
+	check(bA, []byte{0x80, 0x03})
+}

int.go

@@ -20,7 +20,7 @@ func SearchUint64s(a []uint64, x uint64) int {
 
 func (p Uint64Slice) Search(x uint64) int { return SearchUint64s(p, x) }
 
-//-----------------------------------------------------------------------------
+//--------------------------------------------------------------------------------
 
 func PutUint64LE(dest []byte, i uint64) {
 	binary.LittleEndian.PutUint64(dest, i)