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[PATCH] LOG2: Provide ilog2() fallbacks for powerpc

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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>
This commit is contained in:
David Howells 2006-12-08 02:37:53 -08:00 committed by Linus Torvalds
parent 39d61db0ed
commit ef55d53caa
3 changed files with 23 additions and 12 deletions
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4
arch/powerpc/Kconfig
View File

@ -43,11 +43,11 @@ config RWSEM_XCHGADD_ALGORITHM
config ARCH_HAS_ILOG2_U32
bool
default n
default y
config ARCH_HAS_ILOG2_U64
bool
default n
default y if 64BIT
config GENERIC_HWEIGHT
bool

21
include/asm-powerpc/bitops.h
View File

@ -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

10
include/asm-powerpc/page_32.h
View File

@ -26,15 +26,7 @@ extern void clear_pages(void *page, int order);
static inline void clear_page(void *page) { clear_pages(page, 0); }
extern void copy_page(void *to, void *from);
/* Pure 2^n version of get_order */
extern __inline__ int get_order(unsigned long size)
{
int lz;
size = (size-1) >> PAGE_SHIFT;
asm ("cntlzw %0,%1" : "=r" (lz) : "r" (size));
return 32 - lz;
}
#include <asm-generic/page.h>
#endif /* __ASSEMBLY__ */