#include <unistd.h>

#include "concurrency.h"

void walltime_start(walltime_t* start)
{
	clock_gettime(CLOCK_MONOTONIC, start);
}

double walltime_elapsed_from(const walltime_t* start)
{
	walltime_t finish;
	clock_gettime(CLOCK_MONOTONIC, &finish);
	return walltime_elapsed_between(start, &finish);
}

double walltime_elapsed_between(const walltime_t* start, const walltime_t* finish)
{
	double elapsed = (finish->tv_sec - start->tv_sec);
	elapsed += (finish->tv_nsec - start->tv_nsec) / 1000000000.0;

	return elapsed;
}

long concurrency_cpu_count(void)
{
	return sysconf(_SC_NPROCESSORS_ONLN);
}