libfrog: add bit manipulation functions

Duplicate the libxfs bit manipulation functions -- this is for programs
that don't need libxfs.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/include/bitops.h b/include/bitops.h
index 7774950ad59c9fc2933fe14876162d2373628a36..dd561c26b82665b08f2749db6ea44de77e231557 100644 (file)
--- a/include/bitops.h
+++ b/include/bitops.h
@@ -56,4 +56,62 @@ static inline unsigned fls_long(unsigned long l)
  */
 #define ffz(x) ffs(~(x))
 
+/*
+ * XFS bit manipulation routines.  Repeated here so that some programs
+ * don't have to link in all of libxfs just to have bit manipulation.
+ */
+
+/*
+ * masks with n high/low bits set, 64-bit values
+ */
+static inline uint64_t mask64hi(int n)
+{
+       return (uint64_t)-1 << (64 - (n));
+}
+static inline uint32_t mask32lo(int n)
+{
+       return ((uint32_t)1 << (n)) - 1;
+}
+static inline uint64_t mask64lo(int n)
+{
+       return ((uint64_t)1 << (n)) - 1;
+}
+
+/* Get high bit set out of 32-bit argument, -1 if none set */
+static inline int highbit32(uint32_t v)
+{
+       return fls(v) - 1;
+}
+
+/* Get high bit set out of 64-bit argument, -1 if none set */
+static inline int highbit64(uint64_t v)
+{
+       return fls64(v) - 1;
+}
+
+/* Get low bit set out of 32-bit argument, -1 if none set */
+static inline int lowbit32(uint32_t v)
+{
+       return ffs(v) - 1;
+}
+
+/* Get low bit set out of 64-bit argument, -1 if none set */
+static inline int lowbit64(uint64_t v)
+{
+       uint32_t        w = (uint32_t)v;
+       int             n = 0;
+
+       if (w) {        /* lower bits */
+               n = ffs(w);
+       } else {        /* upper bits */
+               w = (uint32_t)(v >> 32);
+               if (w) {
+                       n = ffs(w);
+                       if (n)
+                               n += 32;
+               }
+       }
+       return n - 1;
+}
+
 #endif