text: #include "edge-impulse-sdk/dsp/config.hpp"
  #if EIDSP_LOAD_CMSIS_DSP_SOURCES
  /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_rotation2quaternion_f32.c
   * Description:  Floating-point rotation to quaternion conversion
   *
   *
   * Target Processor: Cortex-M 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 "edge-impulse-sdk/CMSIS/DSP/Include/dsp/quaternion_math_functions.h"
  #include <math.h>
  
  #define RI(x,y) r[(3*(x) + (y))]
  
  
  /**
    @ingroup QuatConv
   */
  
  /**
    @defgroup RotQuat Rotation to Quaternion
  
    Conversions from rotation to quaternion.
   */
  
  /**
    @addtogroup RotQuat
    @{
   */
  
  /**
   * @brief Conversion of a rotation matrix to an equivalent quaternion.
   * @param[in]       pInputRotations points to an array 3x3 rotation matrix (in row order)
   * @param[out]      pOutputQuaternions points to an array quaternions
   * @param[in]       nbQuaternions number of quaternions in the array
   * @return none.
   *
   * q and -q are representing the same rotation. This ambiguity must be taken into
   * account when using the output of this function.
   * 
   */
  
  #if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)
  
  #include "edge-impulse-sdk/CMSIS/DSP/Include/arm_helium_utils.h"
  
  #define R00  vgetq_lane(q1,0)
  #define R01  vgetq_lane(q1,1)
  #define R02  vgetq_lane(q1,2)
  #define R10  vgetq_lane(q1,3)
  #define R11  vgetq_lane(q2,0)
  #define R12  vgetq_lane(q2,1)
  #define R20  vgetq_lane(q2,2)
  #define R21  vgetq_lane(q2,3)
  #define R22  ro22
  
  void arm_rotation2quaternion_f32(const float32_t *pInputRotations, 
      float32_t *pOutputQuaternions,  
      uint32_t nbQuaternions)
  {
     float32_t ro22, trace;
     f32x4_t q1,q2, q; 
  
     float32_t doubler;
     float32_t s;
  
     q = vdupq_n_f32(0.0f);
  
     for(uint32_t nb=0; nb < nbQuaternions; nb++)
     {
        q1 = vld1q(pInputRotations);
        pInputRotations += 4;
  
        q2 = vld1q(pInputRotations);
        pInputRotations += 4;
  
        ro22 = *pInputRotations++;
  
        trace = R00 + R11 + R22;
  
  
        if (trace > 0)
        {
          (void)arm_sqrt_f32(trace + 1.0, &doubler) ; // invs=4*qw
          doubler = 2*doubler;
          s = 1.0 / doubler;
  
          q1 = vmulq_n_f32(q1,s);
          q2 = vmulq_n_f32(q2,s);
  
          q[0] = 0.25 * doubler;
          q[1] = R21 - R12;
          q[2] = R02 - R20;
          q[3] = R10 - R01;
        }
        else if ((R00 > R11) && (R00 > R22) )
        {
          (void)arm_sqrt_f32(1.0 + R00 - R11 - R22,&doubler); // invs=4*qx
          doubler = 2*doubler;
          s = 1.0 / doubler;
  
          q1 = vmulq_n_f32(q1,s);
          q2 = vmulq_n_f32(q2,s);
  
          q[0] = R21 - R12;
          q[1] = 0.25 * doubler;
          q[2] = R01 + R10;
          q[3] = R02 + R20;
        }
        else if (R11 > R22)
        {
          (void)arm_sqrt_f32(1.0 + R11 - R00 - R22,&doubler); // invs=4*qy
          doubler = 2*doubler;
          s = 1.0 / doubler;
  
          q1 = vmulq_n_f32(q1,s);
          q2 = vmulq_n_f32(q2,s);
  
          q[0] = R02 - R20;
          q[1] = R01 + R10;
          q[2] = 0.25 * doubler;
          q[3] = R12 + R21;
        }
        else
        {
          (void)arm_sqrt_f32(1.0 + R22 - R00 - R11,&doubler); // invs=4*qz
          doubler = 2*doubler;
          s = 1.0 / doubler;
  
          q1 = vmulq_n_f32(q1,s);
          q2 = vmulq_n_f32(q2,s);
  
          q[0] = R10 - R01;
          q[1] = R02 + R20;
          q[2] = R12 + R21;
          q[3] = 0.25 * doubler;
        }
  
        vst1q(pOutputQuaternions, q);
        pOutputQuaternions += 4;
  
     }
  }
  
  #else
  void arm_rotation2quaternion_f32(const float32_t *pInputRotations, 
      float32_t *pOutputQuaternions,  
      uint32_t nbQuaternions)
  {
     for(uint32_t nb=0; nb < nbQuaternions; nb++)
     {
         const float32_t *r=&pInputRotations[nb*9];
         float32_t *q=&pOutputQuaternions[nb*4];
  
         float32_t trace = RI(0,0) + RI(1,1) + RI(2,2);
  
         float32_t doubler;
         float32_t s;
  
  
  
        if (trace > 0)
        {
          doubler = sqrtf(trace + 1.0) * 2; // invs=4*qw
          s = 1.0 / doubler;
          q[0] = 0.25 * doubler;
          q[1] = (RI(2,1) - RI(1,2)) * s;
          q[2] = (RI(0,2) - RI(2,0)) * s;
          q[3] = (RI(1,0) - RI(0,1)) * s;
        }
        else if ((RI(0,0) > RI(1,1)) && (RI(0,0) > RI(2,2)) )
        {
          doubler = sqrtf(1.0 + RI(0,0) - RI(1,1) - RI(2,2)) * 2; // invs=4*qx
          s = 1.0 / doubler;
          q[0] = (RI(2,1) - RI(1,2)) * s;
          q[1] = 0.25 * doubler;
          q[2] = (RI(0,1) + RI(1,0)) * s;
          q[3] = (RI(0,2) + RI(2,0)) * s;
        }
        else if (RI(1,1) > RI(2,2))
        {
          doubler = sqrtf(1.0 + RI(1,1) - RI(0,0) - RI(2,2)) * 2; // invs=4*qy
          s = 1.0 / doubler;
          q[0] = (RI(0,2) - RI(2,0)) * s;
          q[1] = (RI(0,1) + RI(1,0)) * s;
          q[2] = 0.25 * doubler;
          q[3] = (RI(1,2) + RI(2,1)) * s;
        }
        else
        {
          doubler = sqrtf(1.0 + RI(2,2) - RI(0,0) - RI(1,1)) * 2; // invs=4*qz
          s = 1.0 / doubler;
          q[0] = (RI(1,0) - RI(0,1)) * s;
          q[1] = (RI(0,2) + RI(2,0)) * s;
          q[2] = (RI(1,2) + RI(2,1)) * s;
          q[3] = 0.25 * doubler;
        }
  
      }
  }
  #endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
  
  /**
    @} end of RotQuat group
   */
  
  #endif // EIDSP_LOAD_CMSIS_DSP_SOURCES
  