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authorKumar Gala <galak@kernel.crashing.org>2008-06-11 10:14:06 -0500
committerWolfgang Denk <wd@denx.de>2008-07-01 21:47:12 +0200
commit4928e97c8531283ca9b368b7c29a8a12e726562a (patch)
tree011b0f09f123e7645b32fc6feaafe3021a7c7723 /include/asm-ppc/bitops.h
parent83002a77cbdf383015ca384eff5fa31722d8e571 (diff)
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PPC: Added fls, fls64, __ilog2_u64, and ffs64 to bitops
fls64, __ilog2_u64, ffs64 are variants that work on an u64, and fls is used to implement them. Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Diffstat (limited to 'include/asm-ppc/bitops.h')
-rw-r--r--include/asm-ppc/bitops.h52
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__
/*