/*
 Simula un falso puerto de comunicaciones.
 */
#include "fake_com_port.h"
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <pthread.h>
#include <misc/timespec_operations.h>
#include <misc/error_checks.h>

// fake device status variables
static volatile int cont=-1;
static volatile int new_data_available = 0;
static volatile char data_buffer = 0;
static volatile int initialized=0;

// internal thread that "receives" data periodically
void *sensor_thread(void *arg) {
  const char *data = "This is a message from the communication port.";
  int data_length = strlen(data);
  struct timespec next_time; // hora de activación
  struct timespec my_period = {1, 100000000};
  
  // lee la hora de la primera activación de la tarea
  clock_gettime(CLOCK_MONOTONIC, &next_time);

  // lazo que se ejecuta periódicamente
  while (1) {

    // espera al próximo periodo
    incr_timespec(&next_time,&my_period);
    CHK( clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
                         &next_time, NULL) );

    if (initialized) {
      // arrive new data
      cont ++;
      data_buffer = data[cont%data_length];
      new_data_available = 1;
      //printf("Port receive %dth byte %c\n", cont, data_buffer);
    }

  }
  return NULL;
}


extern void fake_com_port_outb(unsigned short port, char val) {
  
  pthread_t th_sensor;
  
  switch (port) {

    case FAKE_COM_PORT_CONTROL_REG:  // initialize port
      initialized = 1;

      // crea el thread "sensor_thread" a la máxima prioridad
      CHK( pthread_create (&th_sensor, NULL, sensor_thread, NULL) );
      CHK( pthread_setschedprio(th_sensor, 
				sched_get_priority_max(SCHED_FIFO)) );
      break;

  default:
    // wrong port value: no effect
    printe("fake_com_port_outb: Error: wrong port %d\n", port);
  }
}  

extern char fake_com_port_inb(unsigned short port) {
  char ret;

  switch (port) {

  case FAKE_COM_PORT_DATA_REG:
    // return last received byte of data
    new_data_available = 0;
    ret = data_buffer;
    break;

  case FAKE_COM_PORT_CONTROL_REG:
    // new data available ?
    ret = new_data_available;
    break;

  default:
    // wrong port value
    printe("fake_com_port_inb: Error: wrong port %d\n", port);
    ret = 0;
  }

  return ret;
}