File content as of revision 4:9cee975aadce:

/* ----------------------------------------------------------------------    
* Copyright (C) 2010-2013 ARM Limited. All rights reserved.    
*    
* $Date:        17. January 2013
* $Revision: 	V1.4.1
*    
* Project: 	    CMSIS DSP Library    
* Title:	    arm_pid_init_q31.c    
*    
* Description:	Q31 PID Control initialization function     
*    
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the 
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.  
* ------------------------------------------------------------------- */

#include "arm_math.h"

 /**    
 * @addtogroup PID    
 * @{    
 */

/**    
 * @brief  Initialization function for the Q31 PID Control.   
 * @param[in,out] *S points to an instance of the Q31 PID structure.   
 * @param[in]     resetStateFlag  flag to reset the state. 0 = no change in state 1 = reset the state.   
 * @return none.    
 * \par Description:   
 * \par    
 * The <code>resetStateFlag</code> specifies whether to set state to zero or not. \n   
 * The function computes the structure fields: <code>A0</code>, <code>A1</code> <code>A2</code>    
 * using the proportional gain( \c Kp), integral gain( \c Ki) and derivative gain( \c Kd)    
 * also sets the state variables to all zeros.    
 */

void arm_pid_init_q31(
  arm_pid_instance_q31 * S,
  int32_t resetStateFlag)
{

#ifndef ARM_MATH_CM0_FAMILY

  /* Run the below code for Cortex-M4 and Cortex-M3 */

  /* Derived coefficient A0 */
  S->A0 = __QADD(__QADD(S->Kp, S->Ki), S->Kd);

  /* Derived coefficient A1 */
  S->A1 = -__QADD(__QADD(S->Kd, S->Kd), S->Kp);


#else

  /* Run the below code for Cortex-M0 */

  q31_t temp;

  /* Derived coefficient A0 */
  temp = clip_q63_to_q31((q63_t) S->Kp + S->Ki);
  S->A0 = clip_q63_to_q31((q63_t) temp + S->Kd);

  /* Derived coefficient A1 */
  temp = clip_q63_to_q31((q63_t) S->Kd + S->Kd);
  S->A1 = -clip_q63_to_q31((q63_t) temp + S->Kp);

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

  /* Derived coefficient A2 */
  S->A2 = S->Kd;

  /* Check whether state needs reset or not */
  if(resetStateFlag)
  {
    /* Clear the state buffer.  The size will be always 3 samples */
    memset(S->state, 0, 3u * sizeof(q31_t));
  }

}

/**    
 * @} end of PID group    
 */