2 * Copyright (C) 2005-2013 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
8 /** \file time.c Helper functions for dealing with time values. */
11 * Convert struct timeval to milliseconds.
13 * \param tv The time value value to convert.
15 * \return The number of milliseconds in \a tv.
17 long unsigned tv2ms(const struct timeval *tv)
19 return tv->tv_sec * 1000 + (tv->tv_usec + 500)/ 1000;
23 * Convert milliseconds to a struct timeval.
25 * \param n The number of milliseconds.
26 * \param tv Result pointer.
28 void ms2tv(long unsigned n, struct timeval *tv)
30 tv->tv_sec = n / 1000;
31 tv->tv_usec = (n % 1000) * 1000;
35 * Convert a double to a struct timeval.
37 * \param x The value to convert.
38 * \param tv Result pointer.
40 void d2tv(double x, struct timeval *tv)
43 tv->tv_usec = (x - (double)tv->tv_sec) * 1000.0 * 1000.0 + 0.5;
47 * Compute the difference of two time values.
50 * \param a Subtrahend.
51 * \param diff Result pointer.
53 * If \a diff is not \p NULL, it contains the absolute value |\a b - \a a| on
56 * \return If \a b < \a a, this function returns -1, otherwise it returns 1.
58 int tv_diff(const struct timeval *b, const struct timeval *a,
63 if ((b->tv_sec < a->tv_sec) ||
64 ((b->tv_sec == a->tv_sec) && (b->tv_usec < a->tv_usec))) {
65 const struct timeval *tmp = a;
72 diff->tv_sec = b->tv_sec - a->tv_sec;
73 if (b->tv_usec < a->tv_usec) {
75 diff->tv_usec = 1000 * 1000 - a->tv_usec + b->tv_usec;
77 diff->tv_usec = b->tv_usec - a->tv_usec;
82 * Add two time values.
84 * \param a First addend.
85 * \param b Second addend.
86 * \param sum Contains the sum \a a + \a b on return.
88 void tv_add(const struct timeval *a, const struct timeval *b,
91 sum->tv_sec = a->tv_sec + b->tv_sec;
92 if (a->tv_usec + b->tv_usec >= 1000 * 1000) {
94 sum->tv_usec = a->tv_usec + b->tv_usec - 1000 * 1000;
96 sum->tv_usec = a->tv_usec + b->tv_usec;
100 * Compute integer multiple of given struct timeval.
102 * \param mult The integer value to multiply with.
103 * \param tv The timevalue to multiply.
105 * \param result Contains \a mult * \a tv on return.
107 void tv_scale(const unsigned long mult, const struct timeval *tv,
108 struct timeval *result)
110 uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) * mult;
112 result->tv_sec = x / 1000 / 1000;
113 result->tv_usec = x % (1000 * 1000);
117 * Compute a fraction of given struct timeval.
119 * \param divisor The integer value to divide by.
120 * \param tv The timevalue to divide.
121 * \param result Contains (1 / mult) * tv on return.
123 void tv_divide(const unsigned long divisor, const struct timeval *tv,
124 struct timeval *result)
126 uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) / divisor;
128 result->tv_sec = x / 1000 / 1000;
129 result->tv_usec = x % (1000 * 1000);
133 * Compute a convex combination of two time values.
135 * \param a The first coefficient.
136 * \param tv1 The first time value.
137 * \param b The second coefficient.
138 * \param tv2 The second time value.
139 * \param result Contains the convex combination upon return.
141 * Compute x := (a * tv1 + b * tv2) / (|a| + |b|) and store |x| in \a result.
142 * Both \a a and \a b may be negative.
144 * \return Zero, 1 or -1, if \a x is zero, positive or negative, respectively.
146 int tv_convex_combination(const long a, const struct timeval *tv1,
147 const long b, const struct timeval *tv2,
148 struct timeval *result)
150 struct timeval tmp1, tmp2, tmp3;
152 unsigned long a1, b1;
154 if (a == 0 && b == 0) {
161 tv_scale(a1, tv1, &tmp1);
162 tv_scale(b1, tv2, &tmp2);
163 if ((a > 0 && b < 0) || (a < 0 && b > 0)) /* subtract */
164 ret = tv_diff(&tmp1, &tmp2, &tmp3);
166 tv_add(&tmp1, &tmp2, &tmp3);
167 tv_divide(a1 + b1, &tmp3, result);
177 * Compute when to send a chunk of an audio file.
179 * \param chunk_num The number of the chunk.
180 * \param chunk_tv The duration of one chunk.
181 * \param stream_start When the first chunk was sent.
182 * \param result The time when to send chunk number \a chunk_num.
184 * This function computes \a stream_start + \a chunk_num * \a chunk_time.
186 void compute_chunk_time(long unsigned chunk_num,
187 struct timeval *chunk_tv, struct timeval *stream_start,
188 struct timeval *result)
192 tv_scale(chunk_num, chunk_tv, &tmp);
193 tv_add(&tmp, stream_start, result);
197 * Retrieve the time of the realtime clock.
199 * \param tv Where to store the result.
201 * Gets the current value of the system-wide real-time clock (identified by id
202 * \p CLOCK_REALTIME). If \a tv is \p NULL, the value is stored in a static
203 * buffer, otherwise it is stored at the location given by \a tv.
205 * \return This function aborts on errors. On success it returns a pointer to
206 * memory containing the current time.
208 * \sa clock_gettime(2), gettimeofday(2).
210 struct timeval *clock_get_realtime(struct timeval *tv)
212 static struct timeval user_friendly;
216 #ifdef HAVE_CLOCK_GETTIME
221 ret = clock_gettime(CLOCK_REALTIME, &t);
223 tv->tv_sec = t.tv_sec;
224 tv->tv_usec = t.tv_nsec / 1000;
227 #include <sys/time.h>
228 gettimeofday(tv, NULL);
229 #endif /* HAVE_CLOCK_GETTIME */