Added angle adjust control loop.
diff --git a/frc971/control_loops/angle_adjust.cc b/frc971/control_loops/angle_adjust.cc
new file mode 100644
index 0000000..a99e9ec
--- /dev/null
+++ b/frc971/control_loops/angle_adjust.cc
@@ -0,0 +1,160 @@
+#include "frc971/control_loops/angle_adjust.h"
+#include "frc971/control_loops/hall_effect_loop.h"
+#include "frc971/control_loops/hall_effect_loop-inl.h"
+
+#include <algorithm>
+
+#include "aos/aos_core.h"
+
+#include "aos/common/messages/RobotState.q.h"
+#include "aos/common/control_loop/control_loops.q.h"
+#include "aos/common/logging/logging.h"
+
+#include "frc971/constants.h"
+#include "frc971/control_loops/angle_adjust_motor_plant.h"
+
+namespace frc971 {
+namespace control_loops {
+
+AngleAdjustMotor::AngleAdjustMotor(
+    control_loops::AngleAdjustLoop *my_angle_adjust)
+    : aos::control_loops::ControlLoop<control_loops::AngleAdjustLoop>(
+        my_angle_adjust),
+    hall_effect_(new StateFeedbackLoop<2, 1, 1>(MakeAngleAdjustLoop()), true),
+    error_count_(0),
+    time_(0.0) {
+  if (testing) {
+    hall_effect_.loop_->StartDataFile("angle_adjust.csv");
+  }
+}
+
+bool AngleAdjustMotor::FetchConstants() {
+  if (!constants::angle_adjust_horizontal_lower_limit(
+          &horizontal_lower_limit_)) {
+    LOG(ERROR, "Failed to fetch the horizontal lower limit constant.\n");
+    return false;
+  }
+  if (!constants::angle_adjust_horizontal_upper_limit(
+          &horizontal_upper_limit_)) {
+    LOG(ERROR, "Failed to fetch the horizontal upper limit constant.\n");
+    return false;
+  }
+  if (!constants::angle_adjust_horizontal_hall_effect_stop_angle(
+          &horizontal_hall_effect_stop_angle_)) {
+    LOG(ERROR, "Failed to fetch the hall effect stop angle constants.\n");
+    return false;
+  }
+  if (!constants::angle_adjust_horizontal_zeroing_speed(
+          &horizontal_zeroing_speed_)) {
+    LOG(ERROR, "Failed to fetch the horizontal zeroing speed constant.\n");
+    return false;
+  }
+
+  return true;
+}
+
+double AngleAdjustMotor::ClipGoal(double goal) const {
+  return std::min(horizontal_upper_limit_,
+                  std::max(horizontal_lower_limit_, goal));
+}
+
+double AngleAdjustMotor::LimitVoltage(double absolute_position,
+                                double voltage) const {
+  if (hall_effect_.state_ == HallEffectLoop<2>::READY) {
+    if (absolute_position >= horizontal_upper_limit_) {
+      voltage = std::min(0.0, voltage);
+    }
+    if (absolute_position <= horizontal_lower_limit_) {
+      voltage = std::max(0.0, voltage);
+    }
+  }
+
+  double limit = (hall_effect_.state_ == HallEffectLoop<2>::READY) ? 12.0 : 5.0;
+  // TODO(aschuh): Remove this line when we are done testing.
+  //limit = std::min(0.3, limit);
+  voltage = std::min(limit, voltage);
+  voltage = std::max(-limit, voltage);
+  return voltage;
+}
+
+// Positive angle is up, and positive power is up.
+void AngleAdjustMotor::RunIteration(
+    const ::aos::control_loops::Goal *goal,
+    const control_loops::AngleAdjustLoop::Position *position,
+    ::aos::control_loops::Output *output,
+    ::aos::control_loops::Status * /*status*/) {
+
+  // Disable the motors now so that all early returns will return with the
+  // motors disabled.
+  if (output) {
+    output->voltage = 0;
+  }
+
+  // Cache the constants to avoid error handling down below.
+  if (!FetchConstants()) {
+    LOG(WARNING, "Failed to fetch constants.\n");
+    return;
+  }
+
+  // Uninitialize the bot if too many cycles pass without an encoder.
+  if (position == NULL) {
+    LOG(WARNING, "no new pos given\n");
+    error_count_++;
+  } else {
+    error_count_ = 0;
+  }
+  if (error_count_ >= 4) {
+    LOG(WARNING, "err_count is %d so forcing a re-zero\n", error_count_);
+    hall_effect_.state_ = HallEffectLoop<2>::UNINITIALIZED;
+  }
+
+  double absolute_position = hall_effect_.loop_->X_hat(0, 0);
+  // Compute the absolute position of the angle adjust.
+  if (position) {
+    hall_effect_sensors_[0] = position->bottom_hall_effect;
+    hall_effect_sensors_[1] = position->middle_hall_effect;
+    calibration_values_[0] = position->bottom_calibration;
+    calibration_values_[1] = position->middle_calibration;
+    absolute_position = position->before_angle;
+  }
+
+  hall_effect_.UpdateZeros(horizontal_hall_effect_stop_angle_,
+              hall_effect_sensors_,
+              calibration_values_,
+              horizontal_zeroing_speed_,
+              absolute_position,
+              position != NULL);
+
+  if (hall_effect_.state_ == HallEffectLoop<2>::READY) {
+    const double limited_goal = ClipGoal(goal->goal);
+    hall_effect_.loop_->R << limited_goal, 0.0;
+  }
+
+  // Update the observer.
+  hall_effect_.loop_->Update(position != NULL, output == NULL);
+
+  if (position) {
+    LOG(DEBUG, "pos=%f bottom_hall: %s middle_hall: %s\n",
+        position->before_angle,
+        position->bottom_hall_effect ? "true" : "false",
+        position->middle_hall_effect ? "true" : "false");
+  }
+
+  if (hall_effect_.state_ == HallEffectLoop<2>::READY) {
+    LOG(DEBUG, "calibrated with: %s hall effect\n",
+        hall_effect_.last_calibration_sensor_ ? "bottom" : "middle");
+  }
+
+  if (output) {
+    output->voltage = LimitVoltage(hall_effect_.absolute_position_,
+                                   hall_effect_.loop_->U(0, 0));
+  }
+
+  if (testing) {
+    hall_effect_.loop_->RecordDatum("angle_adjust.csv", time_);
+  }
+  time_ += dt;
+} // RunIteration
+
+}  // namespace control_loops
+}  // namespace frc971