#include "para.h"
/** \file time.c helper functions for dealing with timeouts */

/**
 * convert struct timeval to milliseconds
 *
 * \param tv the value to convert
 *
 * \return The number off milliseconds in \a tv
 */
long unsigned tv2ms(const struct timeval *tv)
{
	return tv->tv_sec * 1000 + (tv->tv_usec + 500)/ 1000;
}

/**
 * convert milliseconds to struct timeval
 *
 * \param n the number of milliseconds
 * \param tv will be filled in by the function
 */
void ms2tv(long unsigned n, struct timeval *tv)
{
	tv->tv_sec = n / 1000;
	tv->tv_usec = (n % 1000) * 1000;
}

/**
 * convert double to struct timeval
 *
 * \param x the value to convert
 * \param tv converted value is stored here
 */
void d2tv(double x, struct timeval *tv)
{
	tv->tv_sec = x;
	tv->tv_usec = (x - (double)tv->tv_sec) * 1000.0 * 1000.0 + 0.5;
}

/**
 * compute the difference of two time values
 *
 * \param b minuend
 * \param a subtrahend
 * \param diff difference is stored here
 *
 * \return If b > a, compute b - a and return 1. if b < a
 * compute a - b and return -1. If \a diff is not  \p NULL, \a diff gets
 * filled in with the absolute value |b - a|.
 */
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 structs of type timeval
 *
 * \param a first addend
 * \param b second addend
 * \param sum holds the sum upon 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 holds mult * tv upon return
 */
void tv_scale(const unsigned long mult, const struct timeval *tv,
	struct timeval *result)
{
	result->tv_sec = mult * tv->tv_sec;
	result->tv_sec += tv->tv_usec * mult / 1000 / 1000;
	result->tv_usec = tv->tv_usec * mult % (1000 * 1000);
}

/**
 * compute fraction of given struct timeval
 *
 * \param divisor the integer value to divide by
 * \param tv the timevalue to divide
 * \param result holds (1 / mult) * tv upon 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 coefiicent
 * \param tv1 the first time value
 * \param b the second coefiicent
 * \param tv2 the second time value
 * \param result holds the convex combination upon return
 *
 * compute x := (a * tv1 + b * tv2) / (|a| + |b|). a, b may be negative.
 * returns sign(x) and stores |x| in the result pointer.
 */
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, subtract = ((a > 0 && b < 0) || (a < 0 && b > 0));
	unsigned long a1 = PARA_ABS(a), b1 = PARA_ABS(b);

	tv_scale(a1, tv1, &tmp1);
	tv_scale(b1, tv2, &tmp2);
	if (subtract)
		ret = tv_diff(&tmp1, &tmp2, &tmp3);
	else
		tv_add(&tmp1, &tmp2, &tmp3);
	if (a1 + b1)
		tv_divide(a1 + b1, &tmp3, result);
	else {
		result->tv_sec = 0;
		result->tv_usec = 0;
	}
	if (!a || !b) {
		if (a + b < 0)
			ret = -1;
	} else
		if (a < 0)
			ret = -ret;
	return ret;
}