Initial working fully go release

pkg/pva/pvdata/bitset.go

@@ -0,0 +1,73 @@
+package pvdata
+
+import "io"
+
+// BitSet is a variable-length set of bit indices, encoded on the wire as:
+//   compact-size(n_bytes) + n_bytes of little-endian bits.
+// Bit 0 of byte 0 is field index 0, bit 1 of byte 0 is field index 1, etc.
+// Used in pvData Monitor responses for "changed" and "overrun" masks.
+type BitSet struct {
+	bits []byte
+}
+
+// NewBitSet returns an empty BitSet.
+func NewBitSet() BitSet { return BitSet{} }
+
+// Set sets bit i in the BitSet.
+func (bs *BitSet) Set(i int) {
+	byteIdx := i / 8
+	for len(bs.bits) <= byteIdx {
+		bs.bits = append(bs.bits, 0)
+	}
+	bs.bits[byteIdx] |= 1 << (uint(i) % 8)
+}
+
+// Has reports whether bit i is set.
+func (bs *BitSet) Has(i int) bool {
+	byteIdx := i / 8
+	if byteIdx >= len(bs.bits) {
+		return false
+	}
+	return bs.bits[byteIdx]&(1<<(uint(i)%8)) != 0
+}
+
+// ReadBitSet reads a BitSet from r.
+func ReadBitSet(r io.Reader) (BitSet, error) {
+	n, err := ReadSize(r)
+	if err != nil {
+		return BitSet{}, err
+	}
+	if n == 0 {
+		return BitSet{}, nil
+	}
+	buf := make([]byte, n)
+	if _, err := io.ReadFull(r, buf); err != nil {
+		return BitSet{}, err
+	}
+	return BitSet{bits: buf}, nil
+}
+
+// WriteBitSet writes bs to w.
+func WriteBitSet(w io.Writer, bs BitSet) error {
+	if err := WriteSize(w, int64(len(bs.bits))); err != nil {
+		return err
+	}
+	if len(bs.bits) == 0 {
+		return nil
+	}
+	_, err := w.Write(bs.bits)
+	return err
+}
+
+// FieldIndices returns all set bit indices in ascending order.
+func (bs *BitSet) FieldIndices() []int {
+	var out []int
+	for bi, b := range bs.bits {
+		for bit := 0; bit < 8; bit++ {
+			if b&(1<<uint(bit)) != 0 {
+				out = append(out, bi*8+bit)
+			}
+		}
+	}
+	return out
+}