text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_absmax_q31.c
   * Description:  Maximum value of absolute values of a Q31 vector
   *
   * $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/statistics_functions.h"
  
  /**
    @ingroup groupStats
   */
  
  /**
    @addtogroup AbsMax
    @{
   */
  
  /**
    @brief         Maximum value of absolute values of a Q31 vector.
    @param[in]     pSrc       points to the input vector
    @param[in]     blockSize  number of samples in input vector
    @param[out]    pResult    maximum value returned here
    @param[out]    pIndex     index of maximum value returned here
    @return        none
   */
  
  #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
  
  #include "arm_helium_utils.h"
  void arm_absmax_q31(
    const q31_t * pSrc,
          uint32_t blockSize,
          q31_t * pResult,
          uint32_t * pIndex)
  {
      int32_t         blkCnt;     /* loop counters */
      q31x4_t         extremValVec = vdupq_n_s32(Q31_ABSMIN);
      q31_t           maxValue = Q31_ABSMIN;
      uint32x4_t      indexVec;
      uint32x4_t      extremIdxVec;
      mve_pred16_t    p0;
      uint32_t        extremIdxArr[4];
  
      indexVec = vidupq_u32(0U, 1);
  
      blkCnt = blockSize;
      do {
          mve_pred16_t    p = vctp32q(blkCnt);
          q31x4_t         extremIdxVal = vld1q_z_s32(pSrc, p);
  
          extremIdxVal = vabsq(extremIdxVal);
          /*
           * Get current max per lane and current index per lane
           * when a max is selected
           */
          p0 = vcmpgeq_m(extremIdxVal, extremValVec, p);
  
          extremValVec = vorrq_m(extremValVec, extremIdxVal, extremIdxVal, p0);
          /* store per-lane extrema indexes */
          vst1q_p_u32(extremIdxArr, indexVec, p0);
  
          indexVec += 4;
          pSrc += 4;
          blkCnt -= 4;
      }
      while (blkCnt > 0);
  
  
      /* Get max value across the vector   */
      maxValue = vmaxvq(maxValue, extremValVec);
  
      /* set index for lower values to max possible index   */
      p0 = vcmpgeq(extremValVec, maxValue);
      extremIdxVec = vld1q_u32(extremIdxArr);
  
      indexVec = vpselq(extremIdxVec, vdupq_n_u32(blockSize - 1), p0);
      *pIndex = vminvq(blockSize - 1, indexVec);
      *pResult = maxValue;
  }
  #else
  #if defined(ARM_MATH_DSP)
  void arm_absmax_q31(
    const q31_t * pSrc,
          uint32_t blockSize,
          q31_t * pResult,
          uint32_t * pIndex)
  {
          q31_t cur_absmax, out;                     /* Temporary variables to store the output value. */\
          uint32_t blkCnt, outIndex;                     /* Loop counter */                                   \
          uint32_t index;                                /* index of maximum value */                         \
                                                                                                              \
    /* Initialize index value to zero. */                                                                     \
    outIndex = 0U;                                                                                            \
    /* Load first input value that act as reference value for comparision */                                  \
    out = *pSrc++;                                                                                            \
    out = (out > 0) ? out : (q31_t)__QSUB(0, out);                                                                           \
    /* Initialize index of extrema value. */                                                                  \
    index = 0U;                                                                                               \
                                                                                                              \
    /* Loop unrolling: Compute 4 outputs at a time */                                                         \
    blkCnt = (blockSize - 1U) >> 2U;                                                                          \
                                                                                                              \
    while (blkCnt > 0U)                                                                                       \
    {                                                                                                         \
      /* Initialize cur_absmax to next consecutive values one by one */                                         \
      cur_absmax = *pSrc++;                                                                                     \
      cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                \
      /* compare for the extrema value */                                                                     \
      if (cur_absmax > out)                                                                         \
      {                                                                                                       \
        /* Update the extrema value and it's index */                                                         \
        out = cur_absmax;                                                                                       \
        outIndex = index + 1U;                                                                                \
      }                                                                                                       \
                                                                                                              \
      cur_absmax = *pSrc++;                                                                                     \
      cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                \
      if (cur_absmax > out)                                                                         \
      {                                                                                                       \
        out = cur_absmax;                                                                                       \
        outIndex = index + 2U;                                                                                \
      }                                                                                                       \
                                                                                                              \
      cur_absmax = *pSrc++;                                                                                     \
      cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                \
      if (cur_absmax > out)                                                                          \
      {                                                                                                       \
        out = cur_absmax;                                                                                       \
        outIndex = index + 3U;                                                                                \
      }                                                                                                       \
                                                                                                              \
      cur_absmax = *pSrc++;                                                                                     \
      cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                 \
      if (cur_absmax > out)                                                                          \
      {                                                                                                       \
        out = cur_absmax;                                                                                       \
        outIndex = index + 4U;                                                                                \
      }                                                                                                       \
                                                                                                              \
      index += 4U;                                                                                            \
                                                                                                              \
      /* Decrement loop counter */                                                                            \
      blkCnt--;                                                                                               \
    }                                                                                                         \
                                                                                                              \
    /* Loop unrolling: Compute remaining outputs */                                                           \
    blkCnt = (blockSize - 1U) % 4U;                                                                           \
                                                                                                              \
                                                                                                              \
    while (blkCnt > 0U)                                                                                       \
    {                                                                                                         \
      cur_absmax = *pSrc++;                                                                                     \
      cur_absmax = (cur_absmax > 0) ? cur_absmax : (q31_t)__QSUB(0, cur_absmax);                                                                 \
      if (cur_absmax > out)                                                                         \
      {                                                                                                       \
        out = cur_absmax;                                                                                       \
        outIndex = blockSize - blkCnt;                                                                        \
      }                                                                                                       \
                                                                                                              \
      /* Decrement loop counter */                                                                            \
      blkCnt--;                                                                                               \
    }                                                                                                         \
                                                                                                              \
    /* Store the extrema value and it's index into destination pointers */                                    \
    *pResult = out;                                                                                           \
    *pIndex = outIndex;
  }
  #else
  void arm_absmax_q31(
    const q31_t * pSrc,
          uint32_t blockSize,
          q31_t * pResult,
          uint32_t * pIndex)
  {
          q31_t maxVal, out;                             /* Temporary variables to store the output value. */
          uint32_t blkCnt, outIndex;                     /* Loop counter */
  
  
    /* Initialise index value to zero. */
    outIndex = 0U;
    /* Load first input value that act as reference value for comparision */
    out = (*pSrc > 0) ? *pSrc : ((*pSrc == INT32_MIN) ? INT32_MAX : -*pSrc);
    pSrc++;
  
    /* Initialize blkCnt with number of samples */
    blkCnt = (blockSize - 1U);
  
    while (blkCnt > 0U)
    {
      /* Initialize maxVal to the next consecutive values one by one */
      maxVal = (*pSrc > 0) ? *pSrc : ((*pSrc == INT32_MIN) ? INT32_MAX : -*pSrc);
      pSrc++;
  
      /* compare for the maximum value */
      if (out < maxVal)
      {
        /* Update the maximum value and it's index */
        out = maxVal;
        outIndex = blockSize - blkCnt;
      }
  
      /* Decrement loop counter */
      blkCnt--;
    }
  
    /* Store the maximum value and it's index into destination pointers */
    *pResult = out;
    *pIndex = outIndex;
  }
  #endif /* defined(ARM_MATH_DSP) */
  #endif /* defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE) */
  /**
    @} end of AbsMax group
   */
  