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util: New functions for the index of the leftmost or rightmost 1-bit.

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These will acquire a user in an upcoming commit.

Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Ben Pfaff
2012-10-31 17:13:27 -07:00
parent fe9d089882
commit 35bedb6171
1 changed files with 21 additions and 0 deletions
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21
lib/util.h
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@@ -271,6 +271,27 @@ zero_rightmost_1bit(uintmax_t x)
{
return x & (x - 1);
}
/* Returns the index of the rightmost 1-bit in 'x' (e.g. 01011000 => 3), or 32
* if 'x' is 0.
*
* Unlike the other functions for rightmost 1-bits, this function only works
* with 32-bit integers. */
static inline uint32_t
rightmost_1bit_idx(uint32_t x)
{
return x ? ctz(x) : 32;
}
/* Returns the index of the rightmost 1-bit in 'x' (e.g. 01011000 => 6), or 32
* if 'x' is 0.
*
* This function only works with 32-bit integers. */
static inline uint32_t
leftmost_1bit_idx(uint32_t x)
{
return x ? log_2_floor(x) : 32;
}
bool is_all_zeros(const uint8_t *, size_t);
bool is_all_ones(const uint8_t *, size_t);