// rt-ng-esp32-timercountingsem

// https://techtutorialsx.com/2017/10/07/esp32-arduino-timer-interrupts/

// https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/freertos-smp.html

// https://microcontrollerslab.com/freertos-counting-semaphore-examples-arduino/

// JDN 2021

// -------------------
// ESP32 way to do timed semaphores for periodic signalling to be used for sampling etc

char taskList[3000];

hw_timer_t *timer0;
const int prescale = 80;	// 80 MHz  => 1 MHz

SemaphoreHandle_t sem0;
const int sem0PerCnt = 100;	// means sem0 will be signalled every 100th interrupt
volatile int sem0Cnt = 0;

SemaphoreHandle_t sem1;
const int sem1PerCnt = 500;	// means sem1 will be signalled every 500th interrupt
volatile int sem1Cnt = 0;


void IRAM_ATTR
onTimer0 ()
{				// standard functinodeclaration + (!)   IRAM_ATTR which force compiler to place function in interal high speed RAM - for quick run of code

  // periodic timer on sem0
  sem0Cnt++;
  if (sem0PerCnt <= sem0Cnt)
    {
      sem0Cnt = 0;
      xSemaphoreGiveFromISR (sem0, NULL);
    }

  // periodic timer on sem1
  sem1Cnt++;
  if (sem1PerCnt <= sem1Cnt)
    {
      sem1Cnt = 0;
      xSemaphoreGiveFromISR (sem1, NULL);
    }

  // etc
}

// DEBUG ONLY
volatile int loop0 = 0, loop1 = 0;

void
task0 (void *pParms)
{
  int i = 0;
  while (1)
    {
      while (xSemaphoreTake (sem0, 1000) != pdTRUE);	// wait until next periodic signal from timer ISR
      loop0++;

      vTaskDelay (100 / portTICK_PERIOD_MS);	// eat 100 msec cputime

    }
}

void
task1 (void *pParms)
{
  int i = 0;
  while (1)
    {
      while (xSemaphoreTake (sem1, 1000) != pdTRUE);	// wait until next periodic signal from timer ISR
      loop1++;
      vTaskDelay (80 / portTICK_PERIOD_MS);	// eat 80 msec cputime

      // test only
      // if uxSemaphoreGetCount(sem1) return 1 or larger it indicates we are behing because signals from ISR is pilling up
      Serial.print (millis ());
      Serial.print (" sem1 value ");
      Serial.print (uxSemaphoreGetCount (sem1));
      Serial.print (" ");
      Serial.print (loop0);
      Serial.print (" ");
      Serial.println (loop1);

    }
}


void
setup ()
{
  Serial.begin (115200);
  delay (2000);
  Serial.println ("starting");

  // sem0,sem1 ....
  sem0 = xSemaphoreCreateCounting (100, 0);
  sem1 = xSemaphoreCreateCounting (100, 0);


  xTaskCreate (task0, "t0", 2000, NULL, 2, NULL);
  xTaskCreate (task1, "t1", 2000, NULL, 2, NULL);


  // start reaktime timer to be used for doing signalling

  timer0 = timerBegin (0, 80, true);	// 1usec pr tick
  timerAlarmWrite (timer0, 1000, true);	// cyclic timer @ 1 Hz
  timerAttachInterrupt (timer0, onTimer0, true);


  // sem1 ...
  timer0 = timerBegin (0, prescale, true);	// 1 usec pr tick - we have timer 0,1,2,3 - we do only use timert0

  timerAlarmWrite (timer0, 1000, true);	// cyclic timer @ 1000 Hz
  timerAttachInterrupt (timer0, onTimer0, true);

  // GOGO for timers
  timerAlarmEnable (timer0);
}

int fl = 0;
void
loop ()
{
  vTaskDelay (100);
  if (!fl)
    {
      fl = 1;
      vTaskList (taskList);
      Serial.print (taskList);
    }
}