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 *
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#include "src/core/lib/transport/pid_controller.h"

void grpc_pid_controller_init(grpc_pid_controller *pid_controller,
                              double gain_p, double gain_i, double gain_d) {
  pid_controller->gain_p = gain_p;
  pid_controller->gain_i = gain_i;
  pid_controller->gain_d = gain_d;
  grpc_pid_controller_reset(pid_controller);
}

void grpc_pid_controller_reset(grpc_pid_controller *pid_controller) {
  pid_controller->last_error = 0.0;
  pid_controller->error_integral = 0.0;
}

double grpc_pid_controller_update(grpc_pid_controller *pid_controller,
                                  double error, double dt) {
  pid_controller->error_integral += error * dt;
  double diff_error = (error - pid_controller->last_error) / dt;
  pid_controller->last_error = error;
  return dt * (pid_controller->gain_p * error +
               pid_controller->gain_i * pid_controller->error_integral +
               pid_controller->gain_d * diff_error);
}