[U-Boot-Users] [PATCH v3] ppc: Added fls, fls64, __ilog2_u64, and ffs64 to bitops

[Kumar Gala]

fls64, __ilog2_u64, ffs64 are variants that work on an u64 and fls
is used to implement them.

Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
---

Added comment about __ilog2(0) not being generally safe from Haavard Skinnemoen

- k

 include/asm-ppc/bitops.h |   52 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/include/asm-ppc/bitops.h b/include/asm-ppc/bitops.h
index 4e9c608..daa66cf 100644
--- a/include/asm-ppc/bitops.h
+++ b/include/asm-ppc/bitops.h
@@ -152,6 +152,7 @@ extern __inline__ int test_bit(int nr, __const__ volatile void *addr)
 }

 /* Return the bit position of the most significant 1 bit in a word */
+/* - the result is undefined when x == 0 */
 extern __inline__ int __ilog2(unsigned int x)
 {
 	int lz;
@@ -167,6 +168,57 @@ extern __inline__ int ffz(unsigned int x)
 	return __ilog2(x & -x);
 }

+/*
+ * fls: find last (most-significant) bit set.
+ * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
+ *
+ * On powerpc, __ilog2(0) returns -1, but this is not safe in general
+ */
+static __inline__ int fls(unsigned int x)
+{
+	return __ilog2(x) + 1;
+}
+
+/**
+ * fls64 - find last set bit in a 64-bit word
+ * @x: the word to search
+ *
+ * This is defined in a similar way as the libc and compiler builtin
+ * ffsll, but returns the position of the most significant set bit.
+ *
+ * fls64(value) returns 0 if value is 0 or the position of the last
+ * set bit if value is nonzero. The last (most significant) bit is
+ * at position 64.
+ */
+#if BITS_PER_LONG == 32
+static inline int fls64(__u64 x)
+{
+	__u32 h = x >> 32;
+	if (h)
+		return fls(h) + 32;
+	return fls(x);
+}
+#elif BITS_PER_LONG == 64
+static inline int fls64(__u64 x)
+{
+	if (x == 0)
+		return 0;
+	return __ilog2(x) + 1;
+}
+#else
+#error BITS_PER_LONG not 32 or 64
+#endif
+
+static inline int __ilog2_u64(u64 n)
+{
+	return fls64(n) - 1;
+}
+
+static inline int ffs64(u64 x)
+{
+	return __ilog2_u64(x & -x) + 1ull;
+}
+
 #ifdef __KERNEL__

 /*
-- 
1.5.5.1