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Code Issues Releases Wiki Activity

util: New function raw_ctz().

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This will acquire a user in an upcoming commit.

Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Ben Pfaff
2012-08-21 10:47:22 -07:00
parent 3ca1de08b4
commit 0ee140fb69
2 changed files with 43 additions and 24 deletions
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25
lib/util.h
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@@ -242,9 +242,32 @@ char *xreadlink(const char *filename);
char *follow_symlinks(const char *filename);
void ignore(bool x OVS_UNUSED);
/* Returns the number of trailing 0-bits in 'n'. Undefined if 'n' == 0.
*
* This compiles to a single machine instruction ("bsf") with GCC on x86. */
#if !defined(UINT_MAX) || !defined(UINT32_MAX)
#error "Someone screwed up the #includes."
#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
static inline int
raw_ctz(uint32_t n)
{
return __builtin_ctz(n);
}
#else
/* Defined in util.c. */
int raw_ctz(uint32_t n);
#endif
/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
static inline int
ctz(uint32_t n)
{
return n ? raw_ctz(n) : 32;
}
int log_2_floor(uint32_t);
int log_2_ceil(uint32_t);
int ctz(uint32_t);
int popcount(uint32_t);
bool is_all_zeros(const uint8_t *, size_t);