6 * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
8 * Licensed under the GPL v2. For licencing details see COPYING.
11 /** \file time.c Helper functions for dealing with time values. */
14 * Convert struct timeval to milliseconds.
16 * \param tv The time value value to convert.
18 * \return The number off milliseconds in \a tv.
20 long unsigned tv2ms(const struct timeval *tv)
22 return tv->tv_sec * 1000 + (tv->tv_usec + 500)/ 1000;
26 * Convert milliseconds to a struct timeval.
28 * \param n The number of milliseconds.
29 * \param tv Result pointer.
31 void ms2tv(long unsigned n, struct timeval *tv)
33 tv->tv_sec = n / 1000;
34 tv->tv_usec = (n % 1000) * 1000;
38 * Convert a double to a struct timeval.
40 * \param x The value to convert.
41 * \param tv Result pointer.
43 void d2tv(double x, struct timeval *tv)
46 tv->tv_usec = (x - (double)tv->tv_sec) * 1000.0 * 1000.0 + 0.5;
50 * Compute the difference of two time values.
53 * \param a Subtrahend.
54 * \param diff Result pointer.
56 * If \a diff is not \p NULL, it contains the absolute value |\a b - \a a| on
59 * \return If \a b < \a a, this function returns -1, otherwise it returns 1.
61 int tv_diff(const struct timeval *b, const struct timeval *a, struct timeval *diff)
65 if ((b->tv_sec < a->tv_sec) ||
66 ((b->tv_sec == a->tv_sec) && (b->tv_usec < a->tv_usec))) {
67 const struct timeval *tmp = a;
74 diff->tv_sec = b->tv_sec - a->tv_sec;
75 if (b->tv_usec < a->tv_usec) {
77 diff->tv_usec = 1000 * 1000 - a->tv_usec + b->tv_usec;
79 diff->tv_usec = b->tv_usec - a->tv_usec;
84 * Add two time values.
86 * \param a First addend.
87 * \param b Second addend.
88 * \param sum Contains the sum \a + \a b on return.
90 void tv_add(const struct timeval *a, const struct timeval *b,
93 sum->tv_sec = a->tv_sec + b->tv_sec;
94 if (a->tv_usec + b->tv_usec >= 1000 * 1000) {
96 sum->tv_usec = a->tv_usec + b->tv_usec - 1000 * 1000;
98 sum->tv_usec = a->tv_usec + b->tv_usec;
102 * Compute integer multiple of given struct timeval.
104 * \param mult The integer value to multiply with.
105 * \param tv The timevalue to multiply.
107 * \param result Contains \a mult * \a tv on return.
109 void tv_scale(const unsigned long mult, const struct timeval *tv,
110 struct timeval *result)
112 result->tv_sec = mult * tv->tv_sec;
113 result->tv_sec += tv->tv_usec * mult / 1000 / 1000;
114 result->tv_usec = tv->tv_usec * mult % (1000 * 1000);
118 * Compute a fraction of given struct timeval.
120 * \param divisor The integer value to divide by.
121 * \param tv The timevalue to divide.
122 * \param result Contains (1 / mult) * tv on return.
124 void tv_divide(const unsigned long divisor, const struct timeval *tv,
125 struct timeval *result)
127 uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) / divisor;
129 result->tv_sec = x / 1000 / 1000;
130 result->tv_usec = x % (1000 * 1000);