[PATCH] LOG2: Provide ilog2() fallbacks for powerpc
Provide ilog2() fallbacks for powerpc for 32-bit numbers and 64-bit numbers on
ppc64.
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-powerpc/bitops.h b/include/asm-powerpc/bitops.h
index c341063..0288144 100644
--- a/include/asm-powerpc/bitops.h
+++ b/include/asm-powerpc/bitops.h
@@ -190,7 +190,8 @@
* Return the zero-based bit position (LE, not IBM bit numbering) of
* the most significant 1-bit in a double word.
*/
-static __inline__ int __ilog2(unsigned long x)
+static __inline__ __attribute__((const))
+int __ilog2(unsigned long x)
{
int lz;
@@ -198,6 +199,24 @@
return BITS_PER_LONG - 1 - lz;
}
+static inline __attribute__((const))
+int __ilog2_u32(u32 n)
+{
+ int bit;
+ asm ("cntlzw %0,%1" : "=r" (bit) : "r" (n));
+ return 31 - bit;
+}
+
+#ifdef __powerpc64__
+static inline __attribute__((const))
+int __ilog2_u64(u32 n)
+{
+ int bit;
+ asm ("cntlzd %0,%1" : "=r" (bit) : "r" (n));
+ return 63 - bit;
+}
+#endif
+
/*
* Determines the bit position of the least significant 0 bit in the
* specified double word. The returned bit position will be