New upstream snapshot

[bcachefs-tools-debian] / libbcachefs / varint.c

diff --git a/libbcachefs/varint.c b/libbcachefs/varint.c
new file mode 100644 (file)
index 0000000..a3d252c
--- /dev/null
+++ b/libbcachefs/varint.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bitops.h>
+#include <asm/unaligned.h>
+
+#include "varint.h"
+
+int bch2_varint_encode(u8 *out, u64 v)
+{
+       unsigned bits = fls64(v|1);
+       unsigned bytes = DIV_ROUND_UP(bits, 7);
+
+       if (likely(bytes < 9)) {
+               v <<= bytes;
+               v |= ~(~0 << (bytes - 1));
+       } else {
+               *out++ = 255;
+               bytes = 9;
+       }
+
+       put_unaligned_le64(v, out);
+       return bytes;
+}
+
+int bch2_varint_decode(const u8 *in, const u8 *end, u64 *out)
+{
+       u64 v = get_unaligned_le64(in);
+       unsigned bytes = ffz(v & 255) + 1;
+
+       if (unlikely(in + bytes > end))
+               return -1;
+
+       if (likely(bytes < 9)) {
+               v >>= bytes;
+               v &= ~(~0ULL << (7 * bytes));
+       } else {
+               v = get_unaligned_le64(++in);
+       }
+
+       *out = v;
+       return bytes;
+}