From 35bedb6171b62dd528e01dbeb8943bb841365bf5 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Wed, 31 Oct 2012 17:13:27 -0700 Subject: [PATCH] util: New functions for the index of the leftmost or rightmost 1-bit. These will acquire a user in an upcoming commit. Signed-off-by: Ben Pfaff --- lib/util.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/lib/util.h b/lib/util.h index c087b53f..70f36919 100644 --- a/lib/util.h +++ b/lib/util.h @@ -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); -- 2.30.2