/*******************************************************************************

    Copyright(C) Jonas 'Sortie' Termansen 2013

    This file is part of the Sortix C Library.

    The Sortix C Library is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or (at your
    option) any later version.

    The Sortix C Library is distributed in the hope that it will be useful, but
    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
    License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.

    time/times.cpp
    Get process execution time statistics.

*******************************************************************************/

#include <sys/times.h>

#include <stdint.h>
#include <time.h>
#include <unistd.h>

// TODO: It is a bit needless to use 64-bit integers on 32-bit platforms and the
//       division is probably very inefficient. In addition, this implementation
//       doesn't hanndle a full 64-bit clock_t, however it won't cause problems
//       before a lot of years has passed, which is unlikely to happen, and the
//       clock function probably shouldn't be used in programs with that long
//       running times.
// TODO: Does this function overflow correctly?
clock_t timespec_to_clock(struct timespec t)
{
	uint64_t ticks_per_second = (uint64_t) sysconf(_SC_CLK_TCK);
	uint64_t sec_contrib = (uint64_t) t.tv_sec * ticks_per_second;
	uint64_t nsec_contrib = (uint64_t) t.tv_nsec * ticks_per_second;
	return (clock_t) (sec_contrib + nsec_contrib / 1000000000);
}

// TODO: This function is crap and has been replaced by timens or clock_gettime.
extern "C" clock_t times(struct tms* buf)
{
	if ( buf )
	{
		struct tmns tmns;
		if ( timens(&tmns) < 0 )
			return (clock_t) -1;
		buf->tms_utime = timespec_to_clock(tmns.tmns_utime);
		buf->tms_stime = timespec_to_clock(tmns.tmns_stime);
		buf->tms_cutime = timespec_to_clock(tmns.tmns_cutime);
		buf->tms_cstime = timespec_to_clock(tmns.tmns_cstime);
	}

	// TODO: Should this be CLOCK_REALTIME instead?
	struct timespec now;
	if ( clock_gettime(CLOCK_MONOTONIC, &now) < 0 )
		return -1;
	return timespec_to_clock(now);
}