Add DMA lidar lite reader.
Change-Id: I8195ff2331029adcdb961b9925f43471cc6b08f9
diff --git a/frc971/wpilib/dma_edge_counting.h b/frc971/wpilib/dma_edge_counting.h
index 813f59c..c8a00ea 100644
--- a/frc971/wpilib/dma_edge_counting.h
+++ b/frc971/wpilib/dma_edge_counting.h
@@ -37,6 +37,38 @@
virtual void AddToDMA(DMA *dma) = 0;
};
+// TODO(brian): Timeout old data.
+class DMAPulseWidthReader : public DMASampleHandlerInterface {
+ public:
+ DMAPulseWidthReader(DigitalInput *input) : input_(input) {}
+ DMAPulseWidthReader() = default;
+
+ void set_input(DigitalInput *input) { input_ = input; }
+
+ double last_width() const { return last_width_; }
+
+ private:
+ void UpdateFromSample(const DMASample & /*sample*/) override;
+ void UpdatePolledValue() override {}
+
+ void PollFromSample(const DMASample & /*sample*/) override {}
+ void AddToDMA(DMA *dma) override {
+ dma->Add(input_);
+ dma->SetExternalTrigger(input_, true, true);
+ }
+
+ DigitalInput *input_ = nullptr;
+
+ // The last DMA reading we got.
+ DMASample prev_sample_;
+ // Whether or not we actually have anything in prev_sample_.
+ bool have_prev_sample_ = false;
+
+ double last_width_ = ::std::numeric_limits<double>::quiet_NaN();
+
+ DISALLOW_COPY_AND_ASSIGN(DMAPulseWidthReader);
+};
+
// Counts edges on a sensor using DMA data and latches encoder values
// corresponding to those edges.
class DMAEdgeCounter : public DMASampleHandlerInterface {