semaphore_value.h

Go to the documentation of this file.

#ifndef SENSESP_SRC_SENSESP_SYSTEM_SEMAPHORE_VALUE_H_
#define SENSESP_SRC_SENSESP_SYSTEM_SEMAPHORE_VALUE_H_
 
#include "sensesp.h"
 
#include <freertos/semphr.h>
 
namespace sensesp {

template <typename T>
class SemaphoreValue : public ValueConsumer<T> {
 public:
  SemaphoreValue() : ValueConsumer<T>() {
    semaphore_ = xSemaphoreCreateBinaryStatic(&semaphore_buffer_);
    mutex_ = xSemaphoreCreateMutexStatic(&mutex_buffer_);
  }

  bool wait(T& destination, unsigned int max_duration_ms) {
    if (xSemaphoreTake(semaphore_, max_duration_ms / portTICK_PERIOD_MS) ==
        pdTRUE) {
      xSemaphoreTake(mutex_, portMAX_DELAY);
      destination = value_;
      xSemaphoreGive(mutex_);
      return true;
    }
    return false;
  }

  bool take(unsigned int max_duration_ms) {
    return xSemaphoreTake(semaphore_, max_duration_ms / portTICK_PERIOD_MS) ==
           pdTRUE;
  }
 
  void set(const T& new_value) override {
    xSemaphoreTake(mutex_, portMAX_DELAY);
    value_ = new_value;
    xSemaphoreGive(mutex_);
    xSemaphoreGive(semaphore_);
  }
 
  void clear() { xSemaphoreTake(semaphore_, 0); }
 
 protected:
  T value_;
  StaticSemaphore_t semaphore_buffer_;
  SemaphoreHandle_t semaphore_;
  StaticSemaphore_t mutex_buffer_;
  SemaphoreHandle_t mutex_;
};
 
}  // namespace sensesp
 
#endif  // SENSESP_SRC_SENSESP_SYSTEM_SEMAPHORE_VALUE_H_