CMSIS-DSP/Source/StatisticsFunctions/arm_absmax_q7.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_absmax_q7.c
 * Description:  Maximum value of absolute values of a Q7 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 Q7 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
 */

#if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE) && defined(__CMSIS_GCC_H)
#pragma GCC warning "Scalar version of arm_absmax_q7 built. Helium version has build issues with gcc."
#endif 


#if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE) &&  !defined(__CMSIS_GCC_H)

#include <stdint.h>
#include "arm_helium_utils.h"

#define MAX_BLKSZ_S8  (UINT8_MAX+1)

static void arm_small_blk_absmax_q7(
    const q7_t * pSrc,
    uint16_t blockSize,
    q7_t * pResult,
    uint32_t * pIndex)
{
    int32_t        blkCnt;     /* loop counters */
    q7x16_t        extremValVec = vdupq_n_s8(Q7_ABSMIN);
    q7_t           maxValue = Q7_ABSMIN;
    uint8x16_t     indexVec;
    uint8x16_t     extremIdxVec;
    mve_pred16_t   p0;
    uint8_t        extremIdxArr[16];

    indexVec = vidupq_u8(0U, 1);

    blkCnt = blockSize;
    do {
        mve_pred16_t    p = vctp8q(blkCnt);
        q7x16_t         extremIdxVal = vld1q_z_s8(pSrc, p);

        extremIdxVal = vqabsq(extremIdxVal);
        /*
         * Get current max per lane and current index per lane
         * when a max is selected
         */
        p0 = vcmpgtq_m(extremIdxVal, extremValVec, p);

        extremValVec = vorrq_m(extremValVec, extremIdxVal, extremIdxVal, p0);
        /* store per-lane extrema indexes */
        vst1q_p_u8(extremIdxArr, indexVec, p0);

        indexVec += 16;
        pSrc += 16;
        blkCnt -= 16;
    }
    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_u8(extremIdxArr);

    indexVec = vpselq(extremIdxVec, vdupq_n_u8(blockSize - 1), p0);
    *pIndex = vminvq_u8(blockSize - 1, indexVec);
    *pResult = maxValue;
}

void arm_absmax_q7(
  const q7_t * pSrc,
        uint32_t blockSize,
        q7_t * pResult,
        uint32_t * pIndex)
{
    int32_t   totalSize = blockSize;

    if (totalSize <= MAX_BLKSZ_S8)
    {
        arm_small_blk_absmax_q7(pSrc, blockSize, pResult, pIndex);
    }
    else
    {
        uint32_t  curIdx = 0;
        q7_t      curBlkExtr = Q7_MIN;
        uint32_t  curBlkPos = 0;
        uint32_t  curBlkIdx = 0;
        /*
         * process blocks of 255 elts
         */
        while (totalSize >= MAX_BLKSZ_S8)
        {
            const q7_t     *curSrc = pSrc;

            arm_small_blk_absmax_q7(curSrc, MAX_BLKSZ_S8, pResult, pIndex);
            if (*pResult > curBlkExtr)
            {
                /*
                 * update partial extrema
                 */
                curBlkExtr = *pResult;
                curBlkPos = *pIndex;
                curBlkIdx = curIdx;
            }
            curIdx++;
            pSrc += MAX_BLKSZ_S8;
            totalSize -= MAX_BLKSZ_S8;
        }
        /*
         * remainder
         */
        arm_small_blk_absmax_q7(pSrc, totalSize, pResult, pIndex);
        if (*pResult > curBlkExtr)
        {
            curBlkExtr = *pResult;
            curBlkPos = *pIndex;
            curBlkIdx = curIdx;
        }
        *pIndex = curBlkIdx * MAX_BLKSZ_S8 + curBlkPos;
        *pResult = curBlkExtr;
    }
}
#else
#if defined(ARM_MATH_DSP)
void arm_absmax_q7(
  const q7_t * pSrc,
        uint32_t blockSize,
        q7_t * pResult,
        uint32_t * pIndex)
{
        q7_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 : (q7_t)__QSUB8(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 : (q7_t)__QSUB8(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 : (q7_t)__QSUB8(0, cur_absmax);                                                                \
    if (cur_absmax > out)                                                                         \
    {                                                                                                       \
      out = cur_absmax;                                                                                       \
      outIndex = index + 2U;                                                                                \
    }                                                                                                       \
                                                                                                            \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q7_t)__QSUB8(0, cur_absmax);                                                                \
    if (cur_absmax > out)                                                                          \
    {                                                                                                       \
      out = cur_absmax;                                                                                       \
      outIndex = index + 3U;                                                                                \
    }                                                                                                       \
                                                                                                            \
    cur_absmax = *pSrc++;                                                                                     \
    cur_absmax = (cur_absmax > 0) ? cur_absmax : (q7_t)__QSUB8(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 : (q7_t)__QSUB8(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_q7(
  const q7_t * pSrc,
        uint32_t blockSize,
        q7_t * pResult,
        uint32_t * pIndex)
{
       q7_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 == (q7_t) 0x80) ? (q7_t) 0x7f : -*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 == (q7_t) 0x80) ? (q7_t) 0x7f : -*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
 */