[fix] package nazabits: BitWriter::WriteBit如果原数据不为非零值时，会错误覆盖非写入的位

pkg/nazabits/bits.go

@@ -84,7 +84,11 @@ func NewBitWriter(b []byte) BitWriter {
 
 // @param b: 当b不为0和1时，取b的最低位
 func (bw *BitWriter) WriteBit(b uint8) {
-	bw.core[bw.index] |= (b & 0x1) << (7 - bw.pos)
+	if b&0x1 == 1 {
+		bw.core[bw.index] |= 1 << (7 - bw.pos)
+	} else {
+		bw.core[bw.index] &= ^(1 << (7 - bw.pos))
+	}
 	bw.pos++
 	if bw.pos == 8 {
 		bw.pos = 0

pkg/nazabits/bits_test.go

@@ -147,6 +147,19 @@ func TestBitWriter_WriteBit(t *testing.T) {
 	}
 	assert.Equal(t, uint8(48), v[0])
 	assert.Equal(t, uint8(57), v[1])
+
+	// 对非0原值进行位写入
+	v = []uint8{0xF0}
+	bw = nazabits.NewBitWriter(v)
+	bw.WriteBit(0)
+	bw.WriteBit(0)
+	bw.WriteBit(0)
+	bw.WriteBit(0)
+	bw.WriteBit(1)
+	bw.WriteBit(1)
+	bw.WriteBit(1)
+	bw.WriteBit(1)
+	assert.Equal(t, uint8(0x0F), v[0])
 }
 
 func TestBitWriter_WriteBits8(t *testing.T) {