refstore/reftable: Add basic implementation

1 files changed, 36 insertions, 0 deletions

diff --git a/refstore/reftable/parse_helpers.go b/refstore/reftable/parse_helpers.go
new file mode 100644
index 00000000..b5da555e
--- /dev/null
+++ b/refstore/reftable/parse_helpers.go
@@ -0,0 +1,36 @@
+package reftable
+
+import "fmt"
+
+// readUint24 reads a 24-bit big-endian unsigned integer.
+func readUint24(b []byte) uint32 {
+	return uint32(b[0])<<16 | uint32(b[1])<<8 | uint32(b[2])
+}
+
+// alignUp rounds pos up to the next multiple of blockSize.
+func alignUp(pos, blockSize int) int {
+	rem := pos % blockSize
+	if rem == 0 {
+		return pos
+	}
+	return pos + (blockSize - rem)
+}
+
+// readVarint decodes one reftable/ofs-delta style varint.
+func readVarint(buf []byte, off, end int) (uint64, int, error) {
+	if off >= end {
+		return 0, 0, fmt.Errorf("unexpected EOF")
+	}
+	b := buf[off]
+	val := uint64(b & 0x7f)
+	off++
+	for b&0x80 != 0 {
+		if off >= end {
+			return 0, 0, fmt.Errorf("unexpected EOF")
+		}
+		b = buf[off]
+		off++
+		val = ((val + 1) << 7) | uint64(b&0x7f)
+	}
+	return val, off, nil
+}