Split //frc971/zeroing into multiple files

It's still a single target, and one massive header file. We should
actually split that up in a future refactoring. However, this does make
it easier to find the relevant parts within each file.

Change-Id: I7abc26f2e3d88da4558f54d56e6db4233cc4c30f
diff --git a/frc971/zeroing/pot_and_absolute_encoder.h b/frc971/zeroing/pot_and_absolute_encoder.h
new file mode 100644
index 0000000..133eaf5
--- /dev/null
+++ b/frc971/zeroing/pot_and_absolute_encoder.h
@@ -0,0 +1,100 @@
+#ifndef FRC971_ZEROING_POT_AND_ABSOLUTE_ENCODER_H_
+#define FRC971_ZEROING_POT_AND_ABSOLUTE_ENCODER_H_
+
+#include <vector>
+
+#include "flatbuffers/flatbuffers.h"
+
+#include "frc971/zeroing/zeroing.h"
+
+namespace frc971 {
+namespace zeroing {
+
+// Estimates the position with an absolute encoder which also reports
+// incremental counts, and a potentiometer.
+class PotAndAbsoluteEncoderZeroingEstimator
+    : public ZeroingEstimator<PotAndAbsolutePosition,
+                              constants::PotAndAbsoluteEncoderZeroingConstants,
+                              PotAndAbsoluteEncoderEstimatorState> {
+ public:
+  explicit PotAndAbsoluteEncoderZeroingEstimator(
+      const constants::PotAndAbsoluteEncoderZeroingConstants &constants);
+
+  // Resets the internal logic so it needs to be re-zeroed.
+  void Reset() override;
+
+  // Updates the sensor values for the zeroing logic.
+  void UpdateEstimate(const PotAndAbsolutePosition &info) override;
+
+  void TriggerError() override { error_ = true; }
+
+  bool zeroed() const override { return zeroed_; }
+
+  double offset() const override { return offset_; }
+
+  bool error() const override { return error_; }
+
+  // Returns true if the sample buffer is full.
+  bool offset_ready() const override {
+    return relative_to_absolute_offset_samples_.size() ==
+               constants_.average_filter_size &&
+           offset_samples_.size() == constants_.average_filter_size;
+  }
+
+  // Returns information about our current state.
+  virtual flatbuffers::Offset<State> GetEstimatorState(
+      flatbuffers::FlatBufferBuilder *fbb) const override;
+
+ private:
+  struct PositionStruct {
+    PositionStruct(const PotAndAbsolutePosition &position_buffer)
+        : absolute_encoder(position_buffer.absolute_encoder()),
+          encoder(position_buffer.encoder()),
+          pot(position_buffer.pot()) {}
+    double absolute_encoder;
+    double encoder;
+    double pot;
+  };
+
+  // The zeroing constants used to describe the configuration of the system.
+  const constants::PotAndAbsoluteEncoderZeroingConstants constants_;
+
+  // True if the mechanism is zeroed.
+  bool zeroed_;
+  // Marker to track whether an error has occurred.
+  bool error_;
+  // The first valid offset we recorded. This is only set after zeroed_ first
+  // changes to true.
+  double first_offset_;
+
+  // The filtered absolute encoder.  This is used in the status for calibration.
+  double filtered_absolute_encoder_ = 0.0;
+
+  // Samples of the offset needed to line the relative encoder up with the
+  // absolute encoder.
+  ::std::vector<double> relative_to_absolute_offset_samples_;
+  // Offset between the Pot and Relative encoder position.
+  ::std::vector<double> offset_samples_;
+
+  MoveDetector<PositionStruct, PotAndAbsolutePosition> move_detector_;
+
+  // Estimated offset between the pot and relative encoder.
+  double pot_relative_encoder_offset_ = 0;
+  // Estimated start position of the mechanism
+  double offset_ = 0;
+  // The next position in 'relative_to_absolute_offset_samples_' and
+  // 'encoder_samples_' to be used to store the next sample.
+  int samples_idx_ = 0;
+
+  size_t nan_samples_ = 0;
+
+  // The unzeroed filtered position.
+  double filtered_position_ = 0.0;
+  // The filtered position.
+  double position_ = 0.0;
+};
+
+}  // namespace zeroing
+}  // namespace frc971
+
+#endif  // FRC971_ZEROING_POT_AND_ABSOLUTE_ENCODER_H_