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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include <stdint.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 popcount(n) \
_Generic((n), \
unsigned char: __builtin_popcount(n), \
unsigned short: __builtin_popcount(n), \
unsigned: __builtin_popcount(n), \
unsigned long: __builtin_popcountl(n), \
unsigned long long: __builtin_popcountll(n))
#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;
}
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