frc971/wpilib/dma_edge_counting.h

#ifndef FRC971_WPILIB_DMA_EDGE_COUNTING_H_
#define FRC971_WPILIB_DMA_EDGE_COUNTING_H_

#include <memory>
#include <vector>

#include "aos/common/macros.h"

#include "frc971/wpilib/hall_effect.h"

#include "DigitalSource.h"
#include "Encoder.h"
#include "AnalogInput.h"
#include "Utility.h"
#include "dma.h"

namespace frc971 {
namespace wpilib {

// Generic interface for classes that do something with DMA samples and also
// poll current sensor values.
class DMASampleHandlerInterface {
 public:
  virtual ~DMASampleHandlerInterface() {}

  // Updates values based on a new DMA sample.
  virtual void UpdateFromSample(const DMASample &sample) = 0;

  // Polls the current values and saves them for later reference.
  virtual void UpdatePolledValue() = 0;

  // Fills in the "polled" values from sample.
  // This is only called when a DMA event happens right as we're polling values.
  virtual void PollFromSample(const DMASample &sample) = 0;

  // Adds readings and triggers appropriate to this object to dma.
  virtual void AddToDMA(DMA *dma) = 0;
};

// Counts edges on a sensor using DMA data and latches encoder values
// corresponding to those edges.
class DMAEdgeCounter : public DMASampleHandlerInterface {
 public:
  DMAEdgeCounter(Encoder *encoder, DigitalSource *input)
      : encoder_(encoder), input_(input), inverted_(false) {}
  DMAEdgeCounter(Encoder *encoder, HallEffect *input)
      : encoder_(encoder), input_(input), inverted_(true) {}

  virtual void UpdateFromSample(const DMASample &sample) override;
  virtual void UpdatePolledValue() override {
    polled_value_ = input_->Get();
    polled_encoder_ = encoder_->GetRaw();
  }
  virtual void PollFromSample(const DMASample &sample) override {
    polled_value_ = ExtractValue(sample);
    polled_encoder_ = sample.GetRaw(encoder_);
  }
  virtual void AddToDMA(DMA *dma) override {
    dma->Add(encoder_);
    dma->Add(input_);
  }

  int positive_count() { return pos_edge_count_; }
  int negative_count() { return neg_edge_count_; }
  int last_positive_encoder_value() { return pos_last_encoder_; }
  int last_negative_encoder_value() { return neg_last_encoder_; }

  // Returns the value of the sensor in the last-read DMA sample.
  bool last_value() { return ExtractValue(prev_sample_); }
  // Returns the most recent polled value of the sensor.
  bool polled_value() const { return polled_value_; }
  // Returns the most recent polled reading from the encoder.
  int polled_encoder() const { return polled_encoder_; }

 private:
  bool ExtractValue(const DMASample &sample);

  Encoder *const encoder_;
  DigitalSource *const input_;
  const bool inverted_;

  // The last DMA reading we got.
  DMASample prev_sample_;
  // Whether or not we actually have anything in prev_sample_.
  bool have_prev_sample_ = false;

  // Values related to the positive edge.
  int pos_edge_count_ = 0;
  double pos_edge_time_ = 0.0;
  int pos_last_encoder_ = 0;

  // Values related to the negative edge.
  int neg_edge_count_ = 0;
  double neg_edge_time_ = 0.0;
  int neg_last_encoder_ = 0;

  bool polled_value_ = false;
  int polled_encoder_ = 0;

  DISALLOW_COPY_AND_ASSIGN(DMAEdgeCounter);
};

// This class handles updating the sampled data on multiple
// DMASampleHandlerInterfaces. The caller should create an instance and then
// periodically call RunIteration, retrieving whatever data from the
// DMASampleHandlerInterfaces after each iteration.
class DMASynchronizer {
 public:
  DMASynchronizer(::std::unique_ptr<DMA> dma) : dma_(::std::move(dma)) {}

  // Adds a new handler to this object. This method must not be called after
  // Start().
  void Add(DMASampleHandlerInterface *handler) {
    handler->AddToDMA(dma_.get());
    handlers_.emplace_back(handler);
  }

  // Actually starts watching for DMA samples.
  // Add may not be called any more after this.
  void Start() {
    dma_->Start(1024);
  }

  // Updates all sensor values.
  void RunIteration() {
    SampleSensors();
    CheckDMA();
  }

 private:
  // Reads the state of all the sensors and records it as the polled values of
  // all the inputs.
  void SampleSensors() {
    sample_time_ = GetFPGATime();
    for (auto &c : handlers_) {
      c->UpdatePolledValue();
    }
  }

  // Gets called by the DMA handler to update edge counts.
  void CheckDMA();

  const ::std::unique_ptr<DMA> dma_;
  ::std::vector<DMASampleHandlerInterface *> handlers_;

  // The time at which we most recently read the sensor values.
  double sample_time_ = 0.0;

  DISALLOW_COPY_AND_ASSIGN(DMASynchronizer);
};

}  // namespace wpilib
}  // namespace frc971

#endif  // FRC971_WPILIB_DMA_EDGE_COUNTING_H_