| xf.li | bfc6e71 | 2025-02-07 01:54:34 -0800 | [diff] [blame^] | 1 | /* clock_getres -- Get the resolution of a POSIX clockid_t. |
| 2 | Copyright (C) 1999-2016 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 | <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include <errno.h> |
| 20 | #include <stdint.h> |
| 21 | #include <time.h> |
| 22 | #include <unistd.h> |
| 23 | #include <sys/param.h> |
| 24 | #include <libc-internal.h> |
| 25 | |
| 26 | |
| 27 | #if HP_TIMING_AVAIL |
| 28 | static long int nsec; /* Clock frequency of the processor. */ |
| 29 | |
| 30 | static int |
| 31 | hp_timing_getres (struct timespec *res) |
| 32 | { |
| 33 | if (__glibc_unlikely (nsec == 0)) |
| 34 | { |
| 35 | hp_timing_t freq; |
| 36 | |
| 37 | /* This can only happen if we haven't initialized the `nsec' |
| 38 | variable yet. Do this now. We don't have to protect this |
| 39 | code against multiple execution since all of them should |
| 40 | lead to the same result. */ |
| 41 | freq = __get_clockfreq (); |
| 42 | if (__glibc_unlikely (freq == 0)) |
| 43 | /* Something went wrong. */ |
| 44 | return -1; |
| 45 | |
| 46 | nsec = MAX (UINT64_C (1000000000) / freq, 1); |
| 47 | } |
| 48 | |
| 49 | /* Fill in the values. |
| 50 | The seconds are always zero (unless we have a 1Hz machine). */ |
| 51 | res->tv_sec = 0; |
| 52 | res->tv_nsec = nsec; |
| 53 | |
| 54 | return 0; |
| 55 | } |
| 56 | #endif |
| 57 | |
| 58 | static inline int |
| 59 | realtime_getres (struct timespec *res) |
| 60 | { |
| 61 | long int clk_tck = sysconf (_SC_CLK_TCK); |
| 62 | |
| 63 | if (__glibc_likely (clk_tck != -1)) |
| 64 | { |
| 65 | /* This implementation assumes that the realtime clock has a |
| 66 | resolution higher than 1 second. This is the case for any |
| 67 | reasonable implementation. */ |
| 68 | res->tv_sec = 0; |
| 69 | res->tv_nsec = 1000000000 / clk_tck; |
| 70 | return 0; |
| 71 | } |
| 72 | |
| 73 | return -1; |
| 74 | } |
| 75 | |
| 76 | |
| 77 | /* Get resolution of clock. */ |
| 78 | int |
| 79 | __clock_getres (clockid_t clock_id, struct timespec *res) |
| 80 | { |
| 81 | int retval = -1; |
| 82 | |
| 83 | switch (clock_id) |
| 84 | { |
| 85 | #ifdef SYSDEP_GETRES |
| 86 | SYSDEP_GETRES; |
| 87 | #endif |
| 88 | |
| 89 | #ifndef HANDLED_REALTIME |
| 90 | case CLOCK_REALTIME: |
| 91 | retval = realtime_getres (res); |
| 92 | break; |
| 93 | #endif /* handled REALTIME */ |
| 94 | |
| 95 | default: |
| 96 | #ifdef SYSDEP_GETRES_CPU |
| 97 | SYSDEP_GETRES_CPU; |
| 98 | #endif |
| 99 | #if HP_TIMING_AVAIL |
| 100 | if ((clock_id & ((1 << CLOCK_IDFIELD_SIZE) - 1)) |
| 101 | == CLOCK_THREAD_CPUTIME_ID) |
| 102 | retval = hp_timing_getres (res); |
| 103 | else |
| 104 | #endif |
| 105 | __set_errno (EINVAL); |
| 106 | break; |
| 107 | |
| 108 | #if HP_TIMING_AVAIL && !defined HANDLED_CPUTIME |
| 109 | case CLOCK_PROCESS_CPUTIME_ID: |
| 110 | case CLOCK_THREAD_CPUTIME_ID: |
| 111 | retval = hp_timing_getres (res); |
| 112 | break; |
| 113 | #endif |
| 114 | } |
| 115 | |
| 116 | return retval; |
| 117 | } |
| 118 | weak_alias (__clock_getres, clock_getres) |