/*
 *If a constant has the U suffix, its data type will be the first of the following that can accommodate its value: unsigned short, unsigned int, unsigned long int.
If a constant has the L suffix, its data type will be the first of the following that can accommodate its value: long int, unsigned long int.
If a constant has both L and U suffixes, (LU or UL), its data type will be unsigned long int.
If a constant has the LL, its data type will be long long.
If a constant has the ULL, its data type will be unsigned long long. 
 * */

#include <stdio.h>

//registra la evolucion del tiempo en relojes local y remoto
//optimizar en velocidad

//https://docs.redhat.com/de/documentation/red_hat_enterprise_linux_for_real_time/8/html-single/optimizing_rhel_8_for_real_time_for_low_latency_operation/index#ref_interpreting-hardware-and-firmware-latency-test-results_assembly_running-and-interpreting-hardware-and-firmware-latency-tests
//https://man7.org/linux/man-pages/man7/sched.7.html
#include <sched.h>
void high_priority(void){
	//ajusta schedulle, falla sin privilegios
	//alta prioridad, no es interrumpido hasta retorna
	struct sched_param x;
	int pid=0;
	x.sched_priority=99;
	sched_setscheduler(pid, SCHED_FIFO, &x);
	}

//https://linux.die.net/man/3/clock_gettime
//https://man7.org/linux/man-pages/man2/nanosleep.2.html
#include <stdint.h>
#include <time.h>
#define u64 uint64_t
#define u32 uint32_t

u64 clock2(void){
	struct timespec x;
	clock_gettime(CLOCK_MONOTONIC,&x);
	int64_t a;
	a=(int64_t)(x.tv_sec) * (int64_t)1000000000 + (int64_t)(x.tv_nsec);
	return a;
	}

void nanosleep2(u64 t){
	struct timespec x;
	x.tv_sec =t/(u64)1E9;
	x.tv_nsec=t%(u64)1E9;
	nanosleep(&x,NULL);	
	}

u64 a,ae,b,be,c,ce,d=0;
u64 diff;
const u64 periode=(u64)(1q*60*1E9);

char str[1024];
FILE *fo;
int n=0;

//cada 5 minutos
int main(void){
	printf("reloj local,remoto\n");
	high_priority();
	c=clock2();
loop:
	a=clock2(); 	
	//query_ntp(); //hora remota
	ae=clock2();

	b=clock2();
	nanosleep2(10E9); //ruido_conmutacion_tareas_cada_10ms
	be=clock2();
	
	if(d==0)d=c;else d=ce;
	sprintf(str,"%d %lld %lld 0 %lld %lld 0 %lld \n",n++, a,ae, b,be, d);
	fputs(str,stdout);
	<F2><F2>lectura remota via wget
	// /var/www/localhost/htdocs/users/hub
	fo=fopen("clock_lr.dat","a");
	fputs(str,fo);
	fclose(fo);

	//me duermo con precision
	ce=clock2();
	diff=(ce-c)%periode;
	diff=periode-diff;
	nanosleep2(diff);
	goto loop;
	}