diff options
| author | David Howells <dhowells@redhat.com> | 2006-12-08 02:37:53 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-08 08:28:51 -0800 |
| commit | ef55d53caa055aedee13e77da82740987dd64f2d (patch) | |
| tree | 243bbfca98e504401ea563d6c799ed23c12c08b8 /include/asm-powerpc/bitops.h | |
| parent | 39d61db0edb34d60b83c5e0d62d0e906578cc707 (diff) | |
[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>
Diffstat (limited to 'include/asm-powerpc/bitops.h')
| -rw-r--r-- | include/asm-powerpc/bitops.h | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/include/asm-powerpc/bitops.h b/include/asm-powerpc/bitops.h index c341063d080..0288144ea02 100644 --- a/include/asm-powerpc/bitops.h +++ b/include/asm-powerpc/bitops.h @@ -190,7 +190,8 @@ static __inline__ void set_bits(unsigned long mask, unsigned long *addr) * 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 @@ static __inline__ int __ilog2(unsigned long x) 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 |