/**
 * FreeRTOS Queue Alternate Solution
 * 
 * Demonstrate how it's often easier to use queues instead of counting
 * semaphores to pass information between tasks.
 * 
 * Date: January 24, 2021
 * Author: Shawn Hymel
 * License: 0BSD
 */

// You'll likely need this on vanilla FreeRTOS
//#include <semphr.h>

// Use only core 1 for demo purposes
#if CONFIG_FREERTOS_UNICORE
  static const BaseType_t app_cpu = 0;
#else
  static const BaseType_t app_cpu = 1;
#endif

// Settings
static const uint8_t queue_len = 10;  // Size of queue
static const int num_prod_tasks = 5;  // Number of producer tasks
static const int num_cons_tasks = 2;  // Number of consumer tasks
static const int num_writes = 3;      // Num times each producer writes to buf

// Globals
static SemaphoreHandle_t bin_sem;     // Waits for parameter to be read
static SemaphoreHandle_t mutex;       // Lock access to Serial resource
static QueueHandle_t msg_queue;       // Send data from producer to consumer

//*****************************************************************************
// Tasks

// Producer: write a given number of times to shared buffer
void producer(void *parameters) {

  // Copy the parameters into a local variable
  int num = *(int *)parameters;

  // Release the binary semaphore
  xSemaphoreGive(bin_sem);

  // Fill queue with task number (wait max time if queue is full)
  for (int i = 0; i < num_writes; i++) {
    xQueueSend(msg_queue, (void *)&num, portMAX_DELAY);
  }

  // Delete self task
  vTaskDelete(NULL);
}

// Consumer: continuously read from shared buffer
void consumer(void *parameters) {

  int val;

  // Read from buffer
  while (1) {

    // Read from queue (wait max time if queue is empty)
    xQueueReceive(msg_queue, (void *)&val, portMAX_DELAY);

    // Lock Serial resource with a mutex
    xSemaphoreTake(mutex, portMAX_DELAY);
    Serial.println(val);
    xSemaphoreGive(mutex);
  }
}

//*****************************************************************************
// Main (runs as its own task with priority 1 on core 1)

void setup() {

  char task_name[12];
  
  // Configure Serial
  Serial.begin(115200);

  // Wait a moment to start (so we don't miss Serial output)
  vTaskDelay(1000 / portTICK_PERIOD_MS);
  Serial.println();
  Serial.println("---FreeRTOS Semaphore Solution---");

  // Create mutexes and semaphores before starting tasks
  bin_sem = xSemaphoreCreateBinary();
  mutex = xSemaphoreCreateMutex();

  // Create queue
  msg_queue = xQueueCreate(queue_len, sizeof(int));

  // Start producer tasks (wait for each to read argument)
  for (int i = 0; i < num_prod_tasks; i++) {
    sprintf(task_name, "Producer %i", i);
    xTaskCreatePinnedToCore(producer,
                            task_name,
                            1024,
                            (void *)&i,
                            1,
                            NULL,
                            app_cpu);
    xSemaphoreTake(bin_sem, portMAX_DELAY);
  }

  // Start consumer tasks
  for (int i = 0; i < num_cons_tasks; i++) {
    sprintf(task_name, "Consumer %i", i);
    xTaskCreatePinnedToCore(consumer,
                            task_name,
                            1024,
                            NULL,
                            1,
                            NULL,
                            app_cpu);
  }

  // Notify that all tasks have been created (lock Serial with mutex)
  xSemaphoreTake(mutex, portMAX_DELAY);
  Serial.println("All tasks created");
  xSemaphoreGive(mutex);
}

void loop() {

  // Do nothing but allow yielding to lower-priority tasks
  vTaskDelay(1000 / portTICK_PERIOD_MS);
}