| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| #pragma once |
| |
| #include <stdint.h> |
| |
| #include "macro.h" |
| |
| /* Note: log2(0) == log2(1) == 0 here and below. */ |
| |
| #define CONST_LOG2ULL(x) ((x) > 1 ? (unsigned) __builtin_clzll(x) ^ 63U : 0) |
| #define NONCONST_LOG2ULL(x) ({ \ |
| unsigned long long _x = (x); \ |
| _x > 1 ? (unsigned) __builtin_clzll(_x) ^ 63U : 0; \ |
| }) |
| #define LOG2ULL(x) __builtin_choose_expr(__builtin_constant_p(x), CONST_LOG2ULL(x), NONCONST_LOG2ULL(x)) |
| |
| static inline unsigned log2u64(uint64_t x) { |
| #if __SIZEOF_LONG_LONG__ == 8 |
| return LOG2ULL(x); |
| #else |
| # error "Wut?" |
| #endif |
| } |
| |
| static inline unsigned u32ctz(uint32_t n) { |
| #if __SIZEOF_INT__ == 4 |
| return n != 0 ? __builtin_ctz(n) : 32; |
| #else |
| # error "Wut?" |
| #endif |
| } |
| |
| #define CONST_LOG2U(x) ((x) > 1 ? __SIZEOF_INT__ * 8 - __builtin_clz(x) - 1 : 0) |
| #define NONCONST_LOG2U(x) ({ \ |
| unsigned _x = (x); \ |
| _x > 1 ? __SIZEOF_INT__ * 8 - __builtin_clz(_x) - 1 : 0; \ |
| }) |
| #define LOG2U(x) __builtin_choose_expr(__builtin_constant_p(x), CONST_LOG2U(x), NONCONST_LOG2U(x)) |
| |
| static inline unsigned log2i(int x) { |
| return LOG2U(x); |
| } |
| |
| static inline unsigned log2u(unsigned x) { |
| return LOG2U(x); |
| } |
| |
| static inline unsigned log2u_round_up(unsigned x) { |
| if (x <= 1) |
| return 0; |
| |
| return log2u(x - 1) + 1; |
| } |