//Jens s2021

// freertos considerations

struct rdWrLockTp
{
  SemaphoreHandle_t rdSem, wrSem;
  int rdCount;
};


struct rdWrLockTp rdWrLock1;

volatile int rdInsideFortest = 0;

// RD WR LOCK BY SEMAPHORE

int
rdWrLockInit (struct rdWrLockTp *lock)
{
  lock->rdSem = xSemaphoreCreateMutex ();
  lock->wrSem = xSemaphoreCreateMutex ();
  lock->rdCount = 0;
  return 0;			// ok - no real chk
}

void
rdEnter (struct rdWrLockTp *lock)
{
  while (xSemaphoreTake (lock->rdSem, (TickType_t) 10) != pdTRUE);
  lock->rdCount++;
  if (lock->rdCount == 1)
    {
      while (xSemaphoreTake (lock->wrSem, (TickType_t) 10) != pdTRUE);
    }
  rdInsideFortest++;		// just for test
  xSemaphoreGive (lock->rdSem);
}

void
wrEnter (struct rdWrLockTp *lock)
{
  while (xSemaphoreTake (lock->wrSem, (TickType_t) 10) != pdTRUE);
}

void
rdLeave (struct rdWrLockTp *lock)
{
  while (xSemaphoreTake (lock->rdSem, (TickType_t) 10) != pdTRUE);
  lock->rdCount--;
  rdInsideFortest--;		// for test only
  if (lock->rdCount == 0)
    {
      xSemaphoreGive (lock->wrSem);
    }
  xSemaphoreGive (lock->rdSem);
}

void
wrLeave (struct rdWrLockTp *lock)
{
  xSemaphoreGive (lock->wrSem);
}

void
wr (void *p)
{
  int i = 0;
  while (1)
    {
      delay (random (100, 1000));
      wrEnter (&rdWrLock1);
      Serial.println ("wr in");
      delay (random (100, 2500));
      Serial.println ("wr leaving");
      // just chekking
      if (0 < rdInsideFortest)
	Serial.println ("problemmmmmss");
      wrLeave (&rdWrLock1);

    }
}

volatile int rdNr = 0;

void
rd (void *p)
{
  int n;

  n = (int) p;
  while (1)
    {
      delay (random (100, 1000));
      rdEnter (&rdWrLock1);
      Serial.print ("rd>> ");
      Serial.println (n);
      delay (random (100, 500));
      Serial.print ("rd<<");
      Serial.println (n);
      rdLeave (&rdWrLock1);

    }
}

void
setup ()
{
  Serial.begin (115200);	// for output from task 1
  delay (3000);
  rdWrLockInit (&rdWrLock1);
  xTaskCreate (wr, "wr", 2000, (void *) 0, 2, NULL);
  xTaskCreate (rd, "wr", 2000, (void *) 1, 2, NULL);
  xTaskCreate (rd, "wr", 2000, (void *) 2, 2, NULL);
  xTaskCreate (rd, "wr", 2000, (void *) 3, 2, NULL);
}

void
loop ()
{
  /* loop will never be called */
}