text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_mat_scale_q31.c
   * Description:  Multiplies a Q31 matrix by a scalar
   *
   * $Date:        27. January 2017
   * $Revision:    V.1.5.1
   *
   * Target Processor: Cortex-M cores
   * -------------------------------------------------------------------- */
  /*
   * Copyright (C) 2010-2017 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 "arm_math.h"
  
  /**
   * @ingroup groupMatrix
   */
  
  /**
   * @addtogroup MatrixScale
   * @{
   */
  
  /**
   * @brief Q31 matrix scaling.
   * @param[in]       *pSrc points to input matrix
   * @param[in]       scaleFract fractional portion of the scale factor
   * @param[in]       shift number of bits to shift the result by
   * @param[out]      *pDst points to output matrix structure
   * @return     		The function returns either
   * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.
   *
   * @details
   * <b>Scaling and Overflow Behavior:</b>
   * \par
   * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.31 format.
   * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.
   */
  
  arm_status arm_mat_scale_q31(
    const arm_matrix_instance_q31 * pSrc,
    q31_t scaleFract,
    int32_t shift,
    arm_matrix_instance_q31 * pDst)
  {
    q31_t *pIn = pSrc->pData;                      /* input data matrix pointer */
    q31_t *pOut = pDst->pData;                     /* output data matrix pointer */
    uint32_t numSamples;                           /* total number of elements in the matrix */
    int32_t totShift = shift + 1;                  /* shift to apply after scaling */
    uint32_t blkCnt;                               /* loop counters  */
    arm_status status;                             /* status of matrix scaling      */
    q31_t in1, in2, out1;                          /* temporary variabels */
  
  #if defined (ARM_MATH_DSP)
  
    q31_t in3, in4, out2, out3, out4;              /* temporary variables */
  
  #endif //      #ifndef ARM_MAT_CM0
  
  #ifdef ARM_MATH_MATRIX_CHECK
    /* Check for matrix mismatch  */
    if ((pSrc->numRows != pDst->numRows) || (pSrc->numCols != pDst->numCols))
    {
      /* Set status as ARM_MATH_SIZE_MISMATCH */
      status = ARM_MATH_SIZE_MISMATCH;
    }
    else
  #endif //    #ifdef ARM_MATH_MATRIX_CHECK
    {
      /* Total number of samples in the input matrix */
      numSamples = (uint32_t) pSrc->numRows * pSrc->numCols;
  
  #if defined (ARM_MATH_DSP)
  
      /* Run the below code for Cortex-M4 and Cortex-M3 */
  
      /* Loop Unrolling */
      blkCnt = numSamples >> 2U;
  
      /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
       ** a second loop below computes the remaining 1 to 3 samples. */
      while (blkCnt > 0U)
      {
        /* C(m,n) = A(m,n) * k */
        /* Read values from input */
        in1 = *pIn;
        in2 = *(pIn + 1);
        in3 = *(pIn + 2);
        in4 = *(pIn + 3);
  
        /* multiply input with scaler value */
        in1 = ((q63_t) in1 * scaleFract) >> 32;
        in2 = ((q63_t) in2 * scaleFract) >> 32;
        in3 = ((q63_t) in3 * scaleFract) >> 32;
        in4 = ((q63_t) in4 * scaleFract) >> 32;
  
        /* apply shifting */
        out1 = in1 << totShift;
        out2 = in2 << totShift;
  
        /* saturate the results. */
        if (in1 != (out1 >> totShift))
          out1 = 0x7FFFFFFF ^ (in1 >> 31);
  
        if (in2 != (out2 >> totShift))
          out2 = 0x7FFFFFFF ^ (in2 >> 31);
  
        out3 = in3 << totShift;
        out4 = in4 << totShift;
  
        *pOut = out1;
        *(pOut + 1) = out2;
  
        if (in3 != (out3 >> totShift))
          out3 = 0x7FFFFFFF ^ (in3 >> 31);
  
        if (in4 != (out4 >> totShift))
          out4 = 0x7FFFFFFF ^ (in4 >> 31);
  
  
        *(pOut + 2) = out3;
        *(pOut + 3) = out4;
  
        /* update pointers to process next sampels */
        pIn += 4U;
        pOut += 4U;
  
  
        /* Decrement the numSamples loop counter */
        blkCnt--;
      }
  
      /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
       ** No loop unrolling is used. */
      blkCnt = numSamples % 0x4U;
  
  #else
  
      /* Run the below code for Cortex-M0 */
  
      /* Initialize blkCnt with number of samples */
      blkCnt = numSamples;
  
  #endif /* #if defined (ARM_MATH_DSP) */
  
      while (blkCnt > 0U)
      {
        /* C(m,n) = A(m,n) * k */
        /* Scale, saturate and then store the results in the destination buffer. */
        in1 = *pIn++;
  
        in2 = ((q63_t) in1 * scaleFract) >> 32;
  
        out1 = in2 << totShift;
  
        if (in2 != (out1 >> totShift))
          out1 = 0x7FFFFFFF ^ (in2 >> 31);
  
        *pOut++ = out1;
  
        /* Decrement the numSamples loop counter */
        blkCnt--;
      }
  
      /* Set status as ARM_MATH_SUCCESS */
      status = ARM_MATH_SUCCESS;
    }
  
    /* Return to application */
    return (status);
  }
  
  /**
   * @} end of MatrixScale group
   */
  