1/* timespec -- System time interface 2 3 Copyright (C) 2000, 2002, 2004-2005, 2007, 2009-2014 Free Software 4 Foundation, Inc. 5 6 This program is free software: you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 18 19#if ! defined TIMESPEC_H 20# define TIMESPEC_H 21 22# include <time.h> 23 24#ifndef _GL_INLINE_HEADER_BEGIN 25 #error "Please include config.h first." 26#endif 27_GL_INLINE_HEADER_BEGIN 28#ifndef _GL_TIMESPEC_INLINE 29# define _GL_TIMESPEC_INLINE _GL_INLINE 30#endif 31 32/* Resolution of timespec time stamps (in units per second), and log 33 base 10 of the resolution. */ 34 35enum { TIMESPEC_RESOLUTION = 1000000000 }; 36enum { LOG10_TIMESPEC_RESOLUTION = 9 }; 37 38/* Return a timespec with seconds S and nanoseconds NS. */ 39 40_GL_TIMESPEC_INLINE struct timespec 41make_timespec (time_t s, long int ns) 42{ 43 struct timespec r; 44 r.tv_sec = s; 45 r.tv_nsec = ns; 46 return r; 47} 48 49/* Return negative, zero, positive if A < B, A == B, A > B, respectively. 50 51 For each time stamp T, this code assumes that either: 52 53 * T.tv_nsec is in the range 0..999999999; or 54 * T.tv_sec corresponds to a valid leap second on a host that supports 55 leap seconds, and T.tv_nsec is in the range 1000000000..1999999999; or 56 * T.tv_sec is the minimum time_t value and T.tv_nsec is -1; or 57 T.tv_sec is the maximum time_t value and T.tv_nsec is 2000000000. 58 This allows for special struct timespec values that are less or 59 greater than all possible valid time stamps. 60 61 In all these cases, it is safe to subtract two tv_nsec values and 62 convert the result to integer without worrying about overflow on 63 any platform of interest to the GNU project, since all such 64 platforms have 32-bit int or wider. 65 66 Replacing "(int) (a.tv_nsec - b.tv_nsec)" with something like 67 "a.tv_nsec < b.tv_nsec ? -1 : a.tv_nsec > b.tv_nsec" would cause 68 this function to work in some cases where the above assumption is 69 violated, but not in all cases (e.g., a.tv_sec==1, a.tv_nsec==-2, 70 b.tv_sec==0, b.tv_nsec==999999999) and is arguably not worth the 71 extra instructions. Using a subtraction has the advantage of 72 detecting some invalid cases on platforms that detect integer 73 overflow. 74 75 The (int) cast avoids a gcc -Wconversion warning. */ 76 77_GL_TIMESPEC_INLINE int 78timespec_cmp (struct timespec a, struct timespec b) 79{ 80 return (a.tv_sec < b.tv_sec ? -1 81 : a.tv_sec > b.tv_sec ? 1 82 : (int) (a.tv_nsec - b.tv_nsec)); 83} 84 85/* Return -1, 0, 1, depending on the sign of A. A.tv_nsec must be 86 nonnegative. */ 87_GL_TIMESPEC_INLINE int 88timespec_sign (struct timespec a) 89{ 90 return a.tv_sec < 0 ? -1 : a.tv_sec || a.tv_nsec; 91} 92 93struct timespec timespec_add (struct timespec, struct timespec) 94 _GL_ATTRIBUTE_CONST; 95struct timespec timespec_sub (struct timespec, struct timespec) 96 _GL_ATTRIBUTE_CONST; 97struct timespec dtotimespec (double) 98 _GL_ATTRIBUTE_CONST; 99 100/* Return an approximation to A, of type 'double'. */ 101_GL_TIMESPEC_INLINE double 102timespectod (struct timespec a) 103{ 104 return a.tv_sec + a.tv_nsec / 1e9; 105} 106 107void gettime (struct timespec *); 108int settime (struct timespec const *); 109 110_GL_INLINE_HEADER_END 111 112#endif 113