1 | /* Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc. |
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2 | This file is part of the GNU C Library. |
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3 | |
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4 | The GNU C Library is free software; you can redistribute it and/or |
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5 | modify it under the terms of the GNU Lesser General Public |
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6 | License as published by the Free Software Foundation; either |
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7 | version 2.1 of the License, or (at your option) any later version. |
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8 | |
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9 | The GNU C Library is distributed in the hope that it will be useful, |
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10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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12 | Lesser General Public License for more details. |
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13 | |
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14 | You should have received a copy of the GNU Lesser General Public |
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15 | License along with the GNU C Library; if not, write to the Free |
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16 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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17 | 02111-1307 USA. */ |
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18 | |
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19 | #include <errno.h> |
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20 | #include <stdint.h> |
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21 | #include <time.h> |
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22 | #include <unistd.h> |
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23 | #include <sys/param.h> |
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24 | #include <libc-internal.h> |
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25 | |
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26 | |
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27 | #if HP_TIMING_AVAIL |
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28 | /* Clock frequency of the processor. */ |
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29 | static long int nsec; |
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30 | #endif |
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31 | |
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32 | |
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33 | /* Get resolution of clock. */ |
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34 | int |
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35 | clock_getres (clockid_t clock_id, struct timespec *res) |
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36 | { |
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37 | int retval = -1; |
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38 | |
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39 | switch (clock_id) |
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40 | { |
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41 | case CLOCK_REALTIME: |
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42 | { |
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43 | long int clk_tck = sysconf (_SC_CLK_TCK); |
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44 | |
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45 | if (__builtin_expect (clk_tck != -1, 1)) |
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46 | { |
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47 | /* This implementation assumes that the realtime clock has a |
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48 | resolution higher than 1 second. This is the case for any |
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49 | reasonable implementation. */ |
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50 | res->tv_sec = 0; |
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51 | res->tv_nsec = 1000000000 / clk_tck; |
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52 | |
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53 | retval = 0; |
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54 | } |
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55 | } |
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56 | break; |
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57 | |
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58 | #if HP_TIMING_AVAIL |
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59 | case CLOCK_PROCESS_CPUTIME_ID: |
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60 | case CLOCK_THREAD_CPUTIME_ID: |
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61 | { |
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62 | if (__builtin_expect (nsec == 0, 0)) |
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63 | { |
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64 | hp_timing_t freq; |
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65 | |
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66 | /* This can only happen if we haven't initialized the `freq' |
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67 | variable yet. Do this now. We don't have to protect this |
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68 | code against multiple execution since all of them should |
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69 | lead to the same result. */ |
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70 | freq = __get_clockfreq (); |
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71 | if (__builtin_expect (freq == 0, 0)) |
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72 | /* Something went wrong. */ |
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73 | break; |
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74 | |
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75 | nsec = MAX (UINT64_C (1000000000) / freq, 1); |
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76 | } |
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77 | |
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78 | /* File in the values. The seconds are always zero (unless we |
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79 | have a 1Hz machine). */ |
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80 | res->tv_sec = 0; |
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81 | res->tv_nsec = nsec; |
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82 | |
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83 | retval = 0; |
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84 | } |
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85 | break; |
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86 | #endif |
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87 | |
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88 | default: |
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89 | __set_errno (EINVAL); |
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90 | break; |
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91 | } |
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92 | |
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93 | return retval; |
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94 | } |
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