From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Wed, 6 Dec 2017 15:17:07 +0000 (-0600)
Subject: libfrog: add bit manipulation functions
X-Git-Tag: v4.15.0-rc1~134
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1ca68d672421b76d96f0e79e0bc8208f8deac255;p=thirdparty%2Fxfsprogs-dev.git

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 7774950ad..dd561c26b 100644
--- 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