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/* SPDX-License-Identifier: GPL-2.0 */
#include "para.h"
/** \file time.c Helper functions for dealing with time values. */
/**
* Convert struct timeval to milliseconds.
*
* \param tv The time value value to convert.
*
* \return The number of milliseconds in \a tv.
*/
long unsigned tv2ms(const struct timeval *tv)
{
return tv->tv_sec * 1000 + (tv->tv_usec + 500)/ 1000;
}
/**
* Convert milliseconds to a struct timeval.
*
* \param n The number of milliseconds.
* \param tv Result pointer.
*/
void ms2tv(long unsigned n, struct timeval *tv)
{
tv->tv_sec = n / 1000;
tv->tv_usec = (n % 1000) * 1000;
}
/**
* Compute the difference of two time values.
*
* \param b Minuend.
* \param a Subtrahend.
* \param diff Result pointer.
*
* If \a diff is not \p NULL, it contains the absolute value |\a b - \a a| on
* return.
*
* \return If \a b < \a a, this function returns -1, otherwise it returns 1.
*/
int tv_diff(const struct timeval *b, const struct timeval *a,
struct timeval *diff)
{
int ret = 1;
if ((b->tv_sec < a->tv_sec) ||
((b->tv_sec == a->tv_sec) && (b->tv_usec < a->tv_usec))) {
const struct timeval *tmp = a;
a = b;
b = tmp;
ret = -1;
}
if (!diff)
return ret;
diff->tv_sec = b->tv_sec - a->tv_sec;
if (b->tv_usec < a->tv_usec) {
diff->tv_sec--;
diff->tv_usec = 1000 * 1000 - a->tv_usec + b->tv_usec;
} else
diff->tv_usec = b->tv_usec - a->tv_usec;
return ret;
}
/**
* Add two time values.
*
* \param a First addend.
* \param b Second addend.
* \param sum Contains the sum \a a + \a b on return.
*/
void tv_add(const struct timeval *a, const struct timeval *b,
struct timeval *sum)
{
sum->tv_sec = a->tv_sec + b->tv_sec;
if (a->tv_usec + b->tv_usec >= 1000 * 1000) {
sum->tv_sec++;
sum->tv_usec = a->tv_usec + b->tv_usec - 1000 * 1000;
} else
sum->tv_usec = a->tv_usec + b->tv_usec;
}
/**
* Compute integer multiple of given struct timeval.
*
* \param mult The integer value to multiply with.
* \param tv The timevalue to multiply.
*
* \param result Contains \a mult * \a tv on return.
*/
void tv_scale(const unsigned long mult, const struct timeval *tv,
struct timeval *result)
{
uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) * mult;
result->tv_sec = x / 1000 / 1000;
result->tv_usec = x % (1000 * 1000);
}
/**
* Compute a fraction of given struct timeval.
*
* \param divisor The integer value to divide by.
* \param tv The timevalue to divide.
* \param result Contains (1 / mult) * tv on return.
*/
void tv_divide(const unsigned long divisor, const struct timeval *tv,
struct timeval *result)
{
uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) / divisor;
result->tv_sec = x / 1000 / 1000;
result->tv_usec = x % (1000 * 1000);
}
/**
* Compute a convex combination of two time values.
*
* \param a The first coefficient.
* \param tv1 The first time value.
* \param b The second coefficient.
* \param tv2 The second time value.
* \param result Contains the convex combination upon return.
*
* Compute x := (a * tv1 + b * tv2) / (|a| + |b|) and store |x| in \a result.
* Both \a a and \a b may be negative.
*
* \return Zero, 1 or -1, if \a x is zero, positive or negative, respectively.
*/
int tv_convex_combination(const long a, const struct timeval *tv1,
const long b, const struct timeval *tv2,
struct timeval *result)
{
struct timeval tmp1, tmp2, tmp3;
int ret = 1;
unsigned long a1, b1;
if (a == 0 && b == 0) {
result->tv_sec = 0;
result->tv_usec = 0;
return 0;
}
a1 = PARA_ABS(a);
b1 = PARA_ABS(b);
tv_scale(a1, tv1, &tmp1);
tv_scale(b1, tv2, &tmp2);
if ((a > 0 && b < 0) || (a < 0 && b > 0)) /* subtract */
ret = tv_diff(&tmp1, &tmp2, &tmp3);
else
tv_add(&tmp1, &tmp2, &tmp3);
tv_divide(a1 + b1, &tmp3, result);
if (!a || !b) {
if (a + b < 0)
ret = -1;
} else if (a < 0)
ret = -ret;
return ret;
}
/**
* Compute when to send a chunk of an audio file.
*
* \param chunk_num The number of the chunk.
* \param chunk_tv The duration of one chunk.
* \param stream_start When the first chunk was sent.
* \param result The time when to send chunk number \a chunk_num.
*
* This function computes \a stream_start + \a chunk_num * \a chunk_time.
*/
void compute_chunk_time(long unsigned chunk_num,
struct timeval *chunk_tv, struct timeval *stream_start,
struct timeval *result)
{
struct timeval tmp;
tv_scale(chunk_num, chunk_tv, &tmp);
tv_add(&tmp, stream_start, result);
}
/**
* Retrieve the time of the realtime clock.
*
* \param tv Where to store the result.
*
* Gets the current value of the system-wide real-time clock (identified by id
* \p CLOCK_REALTIME). If \a tv is \p NULL, the value is stored in a static
* buffer, otherwise it is stored at the location given by \a tv.
*
* \return This function aborts on errors. On success it returns a pointer to
* memory containing the current time.
*
* \sa clock_gettime(2), gettimeofday(2).
*/
struct timeval *clock_get_realtime(struct timeval *tv)
{
static struct timeval user_friendly;
struct timespec t;
int ret;
if (!tv)
tv = &user_friendly;
ret = clock_gettime(CLOCK_REALTIME, &t);
assert(ret == 0);
tv->tv_sec = t.tv_sec;
tv->tv_usec = t.tv_nsec / 1000;
return tv;
}
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