diff options
Diffstat (limited to 'include/asm-ppc/bitops.h')
| -rw-r--r-- | include/asm-ppc/bitops.h | 50 |
1 files changed, 25 insertions, 25 deletions
diff --git a/include/asm-ppc/bitops.h b/include/asm-ppc/bitops.h index c981d5fa0..d5506a348 100644 --- a/include/asm-ppc/bitops.h +++ b/include/asm-ppc/bitops.h @@ -6,6 +6,7 @@ #ifndef _PPC_BITOPS_H #define _PPC_BITOPS_H +#include <linux/config.h> #include <asm/system.h> #include <asm/byteorder.h> @@ -16,15 +17,18 @@ extern int test_and_set_bit(int nr, volatile void *addr); extern int test_and_clear_bit(int nr, volatile void *addr); extern int test_and_change_bit(int nr, volatile void *addr); - -/* Returns the number of 0's to the left of the most significant 1 bit */ -extern __inline__ int cntlzw(int bits) -{ - int lz; - - asm ("cntlzw %0,%1" : "=r" (lz) : "r" (bits)); - return lz; -} +/* + * Arguably these bit operations don't imply any memory barrier or + * SMP ordering, but in fact a lot of drivers expect them to imply + * both, since they do on x86 cpus. + */ +#ifdef CONFIG_SMP +#define SMP_WMB "eieio\n" +#define SMP_MB "\nsync" +#else +#define SMP_WMB +#define SMP_MB +#endif /* CONFIG_SMP */ /* * These are if'd out here because using : "cc" as a constraint @@ -95,15 +99,20 @@ extern __inline__ int test_bit(int nr, __const__ volatile void *addr) return ((p[nr >> 5] >> (nr & 0x1f)) & 1) != 0; } -extern __inline__ int ffz(unsigned int x) +/* Return the bit position of the most significant 1 bit in a word */ +extern __inline__ int __ilog2(unsigned int x) { - int n; + int lz; + + asm ("cntlzw %0,%1" : "=r" (lz) : "r" (x)); + return 31 - lz; +} - if (x == ~0) +extern __inline__ int ffz(unsigned int x) +{ + if ((x = ~x) == 0) return 32; - x = ~x & (x+1); /* set LS zero to 1, other bits to 0 */ - __asm__ ("cntlzw %0,%1" : "=r" (n) : "r" (x)); - return 31 - n; + return __ilog2(x & -x); } #ifdef __KERNEL__ @@ -113,19 +122,10 @@ extern __inline__ int ffz(unsigned int x) * the libc and compiler builtin ffs routines, therefore * differs in spirit from the above ffz (man ffs). */ - -#define ffs(x) generic_ffs(x) - -#if 0 -/* untested, someone with PPC knowledge? */ -/* From Alexander Kjeldaas <astor@guardian.no> */ extern __inline__ int ffs(int x) { - int result; - asm ("cntlzw %0,%1" : "=r" (result) : "r" (x)); - return 32 - result; /* IBM backwards ordering of bits */ + return __ilog2(x & -x) + 1; } -#endif /* * hweightN: returns the hamming weight (i.e. the number |