// filename: coretest.c
//
// run a c-program on a specific core
//
// 2024-06-16 ch
//
// https://github.com/WiringPi/WiringPi
// gcc -o coretest coretest.c -l wiringPi 
/*
https://forums.raspberrypi.com/viewtopic.php?t=228727
add this argument to /boot/cmdline.txt:
isolcpus=3
This prevents Linux from scheduling processes on core 3. But interrupts still happen on it, and there is an essential kernel task running on it. Still, it is a good start, but not at all sufficient.
*/
#define _GNU_SOURCE
#include <sched.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <wiringPi.h>
#include <stdbool.h>
#include <stdint.h>

// LED Pin - wiringPi pin 0 is BCM_GPIO 17.

#define LED 0

#define DELAY_US 100

void togglePin()
{
  static bool flag=false;
  if(flag)digitalWrite (LED, HIGH) ;
  else digitalWrite (LED, LOW) ;
  flag=!flag;
}

void setup()
{
  printf ("fastPinToggle\n") ;
  wiringPiSetup ();
  pinMode (LED, OUTPUT) ;
}

uint32_t currentTime = 0;
uint32_t startTime = 1;

void loop()
{
  togglePin();
  do
  {
      currentTime = micros();
  } while ((uint32_t)(currentTime - startTime) <= DELAY_US);
  startTime = currentTime;
}

int main() {
    cpu_set_t cpuset;
    //int core_id = 1;  // Change this to the core you want to run on (0-indexed)
    int core_id = 3;  // Change this to the core you want to run on (0-indexed)
        
    CPU_ZERO(&cpuset);
    CPU_SET(core_id, &cpuset);
    
    pid_t pid = getpid(); // Get the PID of the current process

    if (sched_setaffinity(pid, sizeof(cpu_set_t), &cpuset) == -1) {
        perror("sched_setaffinity");
        exit(EXIT_FAILURE);
    }

    // Your program logic here
    printf("Running on core %d\n", core_id);
    while (1) 
    {
        loop();
        //sleep(1);
    }

    return 0;
}