include/asterisk/time.h

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  * \brief Time-related functions and macros
  21  */
  22
  23 #ifndef _ASTERISK_TIME_H
  24 #define _ASTERISK_TIME_H
  25
  26 #include <sys/time.h>
  27 #include <stdlib.h>
  28
  29 #include "asterisk/inline_api.h"
  30
  31 /* We have to let the compiler learn what types to use for the elements of a
  32    struct timeval since on linux, it's time_t and suseconds_t, but on *BSD,
  33    they are just a long. */
  34 extern struct timeval tv;
  35 typedef typeof(tv.tv_sec) ast_time_t;
  36 typedef typeof(tv.tv_usec) ast_suseconds_t;
  37
  38 /*!
  39  * \brief Computes the difference (in milliseconds) between two \c struct \c timeval instances.
  40  * \param end end of the time period
  41  * \param start beginning of the time period
  42  * \return the difference in milliseconds
  43  */
  44 AST_INLINE_API(
  45 int ast_tvdiff_ms(struct timeval end, struct timeval start),
  46 {
  47         /* the offset by 1,000,000 below is intentional...
  48            it avoids differences in the way that division
  49            is handled for positive and negative numbers, by ensuring
  50            that the divisor is always positive
  51         */
  52         return  ((end.tv_sec - start.tv_sec) * 1000) +
  53                 (((1000000 + end.tv_usec - start.tv_usec) / 1000) - 1000);
  54 }
  55 )
  56
  57 /*!
  58  * \brief Returns true if the argument is 0,0
  59  */
  60 AST_INLINE_API(
  61 int ast_tvzero(const struct timeval t),
  62 {
  63         return (t.tv_sec == 0 && t.tv_usec == 0);
  64 }
  65 )
  66
  67 /*!
  68  * \brief Compres two \c struct \c timeval instances returning
  69  * -1, 0, 1 if the first arg is smaller, equal or greater to the second.
  70  */
  71 AST_INLINE_API(
  72 int ast_tvcmp(struct timeval _a, struct timeval _b),
  73 {
  74         if (_a.tv_sec < _b.tv_sec)
  75                 return -1;
  76         if (_a.tv_sec > _b.tv_sec)
  77                 return 1;
  78         /* now seconds are equal */
  79         if (_a.tv_usec < _b.tv_usec)
  80                 return -1;
  81         if (_a.tv_usec > _b.tv_usec)
  82                 return 1;
  83         return 0;
  84 }
  85 )
  86
  87 /*!
  88  * \brief Returns true if the two \c struct \c timeval arguments are equal.
  89  */
  90 AST_INLINE_API(
  91 int ast_tveq(struct timeval _a, struct timeval _b),
  92 {
  93         return (_a.tv_sec == _b.tv_sec && _a.tv_usec == _b.tv_usec);
  94 }
  95 )
  96
  97 /*!
  98  * \brief Returns current timeval. Meant to replace calls to gettimeofday().
  99  */
 100 AST_INLINE_API(
 101 struct timeval ast_tvnow(void),
 102 {
 103         struct timeval t;
 104         gettimeofday(&t, NULL);
 105         return t;
 106 }
 107 )
 108
 109 /*!
 110  * \brief Returns the sum of two timevals a + b
 111  */
 112 struct timeval ast_tvadd(struct timeval a, struct timeval b);
 113
 114 /*!
 115  * \brief Returns the difference of two timevals a - b
 116  */
 117 struct timeval ast_tvsub(struct timeval a, struct timeval b);
 118
 119 /*!
 120  * \brief Returns a timeval from sec, usec
 121  */
 122 AST_INLINE_API(
 123 struct timeval ast_tv(ast_time_t sec, ast_suseconds_t usec),
 124 {
 125         struct timeval t;
 126         t.tv_sec = sec;
 127         t.tv_usec = usec;
 128         return t;
 129 }
 130 )
 131
 132 /*!
 133  * \brief Returns a timeval corresponding to the duration of n samples at rate r.
 134  * Useful to convert samples to timevals, or even milliseconds to timevals
 135  * in the form ast_samp2tv(milliseconds, 1000)
 136  */
 137 AST_INLINE_API(
 138 struct timeval ast_samp2tv(unsigned int _nsamp, unsigned int _rate),
 139 {
 140         return ast_tv(_nsamp / _rate, (_nsamp % _rate) * (1000000 / _rate));
 141 }
 142 )
 143
 144 #endif /* _ASTERISK_TIME_H */