/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_quaternion_inverse_f32.c
 * Description:  Floating-point quaternion inverse
 *
 * $Date:        23 April 2021
 * $Revision:    V1.9.0
 *
 * Target Processor: Cortex-M and Cortex-A cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "dsp/quaternion_math_functions.h"
#include <math.h>

/**
  @ingroup groupQuaternionMath
 */

/**
  @defgroup QuatInverse Quaternion Inverse

  Compute the inverse of a quaternion.
 */

/**
  @addtogroup QuatInverse
  @{
 */

/**
  @brief         Floating-point quaternion inverse.
  @param[in]     pInputQuaternions            points to the input vector of quaternions
  @param[out]    pInverseQuaternions          points to the output vector of inverse quaternions
  @param[in]     nbQuaternions                number of quaternions in each vector
  @return        none
 */


#if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)

#include "arm_helium_utils.h"

void arm_quaternion_inverse_f32(const float32_t *pInputQuaternions, 
  float32_t *pInverseQuaternions,
  uint32_t nbQuaternions)
{
   f32x4_t vec1,vec2;
   float32_t squaredSum;

   for(uint32_t i=0; i < nbQuaternions; i++)
   {
     
      vec1 = vld1q(pInputQuaternions);
      vec2 = vmulq(vec1,vec1);
      squaredSum = vecAddAcrossF32Mve(vec2);
      

      vec1 = vmulq_n_f32(vec1, 1.0f / squaredSum);
      vec1 = vsetq_lane_f32(-vgetq_lane(vec1, 0),vec1,0);
      vec1 = vnegq_f32(vec1);

      vst1q(pInverseQuaternions, vec1);


      pInputQuaternions   += 4;
      pInverseQuaternions += 4;

   }
}

#else
void arm_quaternion_inverse_f32(const float32_t *pInputQuaternions, 
  float32_t *pInverseQuaternions,
  uint32_t nbQuaternions)
{
   float32_t temp;

   for(uint32_t i=0; i < nbQuaternions; i++)
   {

      temp = SQ(pInputQuaternions[4 * i + 0]) +
             SQ(pInputQuaternions[4 * i + 1]) +
             SQ(pInputQuaternions[4 * i + 2]) +
             SQ(pInputQuaternions[4 * i + 3]);

      pInverseQuaternions[4 * i + 0] = pInputQuaternions[4 * i + 0] / temp;
      pInverseQuaternions[4 * i + 1] = -pInputQuaternions[4 * i + 1] / temp;
      pInverseQuaternions[4 * i + 2] = -pInputQuaternions[4 * i + 2] / temp;
      pInverseQuaternions[4 * i + 3] = -pInputQuaternions[4 * i + 3] / temp;
   }
}
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */

/**
  @} end of QuatInverse group
 */
