| /* timespec -- System time interface |
| |
| Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2019 Free Software |
| Foundation, Inc. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| #if ! defined TIMESPEC_H |
| #define TIMESPEC_H |
| |
| #include <time.h> |
| |
| #ifndef _GL_INLINE_HEADER_BEGIN |
| #error "Please include config.h first." |
| #endif |
| _GL_INLINE_HEADER_BEGIN |
| #ifndef _GL_TIMESPEC_INLINE |
| # define _GL_TIMESPEC_INLINE _GL_INLINE |
| #endif |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| #include "arg-nonnull.h" |
| #include "verify.h" |
| |
| /* Inverse resolution of timespec timestamps (in units per second), |
| and log base 10 of the inverse resolution. */ |
| |
| enum { TIMESPEC_HZ = 1000000000 }; |
| enum { LOG10_TIMESPEC_HZ = 9 }; |
| |
| /* Obsolescent names for backward compatibility. |
| They are misnomers, because TIMESPEC_RESOLUTION is not a resolution. */ |
| |
| enum { TIMESPEC_RESOLUTION = TIMESPEC_HZ }; |
| enum { LOG10_TIMESPEC_RESOLUTION = LOG10_TIMESPEC_HZ }; |
| |
| /* Return a timespec with seconds S and nanoseconds NS. */ |
| |
| _GL_TIMESPEC_INLINE struct timespec |
| make_timespec (time_t s, long int ns) |
| { |
| struct timespec r; |
| r.tv_sec = s; |
| r.tv_nsec = ns; |
| return r; |
| } |
| |
| /* Return negative, zero, positive if A < B, A == B, A > B, respectively. |
| |
| For each timestamp T, this code assumes that either: |
| |
| * T.tv_nsec is in the range 0..999999999; or |
| * T.tv_sec corresponds to a valid leap second on a host that supports |
| leap seconds, and T.tv_nsec is in the range 1000000000..1999999999; or |
| * T.tv_sec is the minimum time_t value and T.tv_nsec is -1; or |
| T.tv_sec is the maximum time_t value and T.tv_nsec is 2000000000. |
| This allows for special struct timespec values that are less or |
| greater than all possible valid timestamps. |
| |
| In all these cases, it is safe to subtract two tv_nsec values and |
| convert the result to integer without worrying about overflow on |
| any platform of interest to the GNU project, since all such |
| platforms have 32-bit int or wider. |
| |
| Replacing "a.tv_nsec - b.tv_nsec" with something like |
| "a.tv_nsec < b.tv_nsec ? -1 : a.tv_nsec > b.tv_nsec" would cause |
| this function to work in some cases where the above assumption is |
| violated, but not in all cases (e.g., a.tv_sec==1, a.tv_nsec==-2, |
| b.tv_sec==0, b.tv_nsec==999999999) and is arguably not worth the |
| extra instructions. Using a subtraction has the advantage of |
| detecting some invalid cases on platforms that detect integer |
| overflow. */ |
| |
| _GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE |
| timespec_cmp (struct timespec a, struct timespec b) |
| { |
| if (a.tv_sec < b.tv_sec) |
| return -1; |
| if (a.tv_sec > b.tv_sec) |
| return 1; |
| |
| /* Pacify gcc -Wstrict-overflow (bleeding-edge circa 2017-10-02). See: |
| https://lists.gnu.org/r/bug-gnulib/2017-10/msg00006.html */ |
| assume (-1 <= a.tv_nsec && a.tv_nsec <= 2 * TIMESPEC_HZ); |
| assume (-1 <= b.tv_nsec && b.tv_nsec <= 2 * TIMESPEC_HZ); |
| |
| return a.tv_nsec - b.tv_nsec; |
| } |
| |
| /* Return -1, 0, 1, depending on the sign of A. A.tv_nsec must be |
| nonnegative. */ |
| _GL_TIMESPEC_INLINE int _GL_ATTRIBUTE_PURE |
| timespec_sign (struct timespec a) |
| { |
| return a.tv_sec < 0 ? -1 : a.tv_sec || a.tv_nsec; |
| } |
| |
| struct timespec timespec_add (struct timespec, struct timespec) |
| _GL_ATTRIBUTE_CONST; |
| struct timespec timespec_sub (struct timespec, struct timespec) |
| _GL_ATTRIBUTE_CONST; |
| struct timespec dtotimespec (double) |
| _GL_ATTRIBUTE_CONST; |
| |
| /* Return an approximation to A, of type 'double'. */ |
| _GL_TIMESPEC_INLINE double |
| timespectod (struct timespec a) |
| { |
| return a.tv_sec + a.tv_nsec / 1e9; |
| } |
| |
| struct timespec current_timespec (void); |
| void gettime (struct timespec *) _GL_ARG_NONNULL ((1)); |
| int settime (struct timespec const *) _GL_ARG_NONNULL ((1)); |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| _GL_INLINE_HEADER_END |
| |
| #endif |