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1/* High precision, low overhead timing functions. AArch64 version.
2 Copyright (C) 2021-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef _HP_TIMING_H
20#define _HP_TIMING_H 1
21
22#include <time.h>
23#include <stdint.h>
24#include <hp-timing-common.h>
25#include <libc-symbols.h>
26
27/* Don't use inline timer in ld.so. */
28#if IS_IN(rtld)
29# define HP_TIMING_INLINE (0)
30#else
31# define HP_TIMING_INLINE (1)
32#endif
33
34typedef uint64_t hp_timing_t;
35
36#define HP_TIMING_NOW(var) \
37 __asm__ __volatile__ ("isb; mrs %0, cntvct_el0" : "=r" (var))
38
39/* Compute elapsed time in nanoseconds. */
40#undef HP_TIMING_DIFF
41#define HP_TIMING_DIFF(Diff, Start, End) \
42({ hp_timing_t freq; \
43 __asm__ __volatile__ ("mrs %0, cntfrq_el0" : "=r" (freq)); \
44 (Diff) = (((End) - (Start)) * UINT64_C(1000000000 >> 6)) / (freq >> 6); \
45})
46
47#endif /* hp-timing.h */
48

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source code of glibc/sysdeps/aarch64/hp-timing.h