3 files changed, 63 insertions, 0 deletions
diff --git a/pkg/util/bitfield.go b/pkg/util/bitfield.go
new file mode 100644
index 0000000..5e2ba06
--- /dev/null
+++ b/pkg/util/bitfield.go
@@ -0,0 +1,31 @@
+package util
+
+import (
+	"fmt"
+	"strings"
+)
+
+func BitfieldString[T ~uint8 | ~uint16 | ~uint32 | ~uint64](bitfield T, bitnames []string) string {
+	var out strings.Builder
+	fmt.Fprintf(&out, "0x%0X", uint64(bitfield))
+	if bitfield == 0 {
+		out.WriteString("(none)")
+	} else {
+		rest := bitfield
+		sep := '('
+		for i := 0; rest != 0; i++ {
+			if rest&(1<<i) != 0 {
+				out.WriteRune(sep)
+				if i < len(bitnames) {
+					out.WriteString(bitnames[i])
+				} else {
+					fmt.Fprintf(&out, "(1<<%d)", i)
+				}
+				sep = '|'
+			}
+			rest &^= 1 << i
+		}
+		out.WriteRune(')')
+	}
+	return out.String()
+}
diff --git a/pkg/util/int.go b/pkg/util/int.go
new file mode 100644
index 0000000..fab553d
--- /dev/null
+++ b/pkg/util/int.go
@@ -0,0 +1,3 @@
+package util
+
+const MaxUint64pp = 0x1_00000000_00000000
diff --git a/pkg/util/ref.go b/pkg/util/ref.go
new file mode 100644
index 0000000..69f7db4
--- /dev/null
+++ b/pkg/util/ref.go
@@ -0,0 +1,29 @@
+package util
+
+import (
+	"lukeshu.com/btrfs-tools/pkg/binstruct"
+)
+
+type File[A ~int64] interface {
+	Name() string
+	Size() (A, error)
+	ReadAt(p []byte, off A) (n int, err error)
+}
+
+type Ref[A ~int64, T any] struct {
+	File File[A]
+	Addr A
+	Data T
+}
+
+func (r *Ref[A, T]) Read() error {
+	size := binstruct.StaticSize(r.Data)
+	buf := make([]byte, size)
+	if _, err := r.File.ReadAt(buf, r.Addr); err != nil {
+		return err
+	}
+	if _, err := binstruct.Unmarshal(buf, &r.Data); err != nil {
+		return err
+	}
+	return nil
+}