text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_mat_scale_q15.c
   * Description:  Multiplies a Q15 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 Q15 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 1.15 format.
   * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
   */
  
  arm_status arm_mat_scale_q15(
    const arm_matrix_instance_q15 * pSrc,
    q15_t scaleFract,
    int32_t shift,
    arm_matrix_instance_q15 * pDst)
  {
    q15_t *pIn = pSrc->pData;                      /* input data matrix pointer */
    q15_t *pOut = pDst->pData;                     /* output data matrix pointer */
    uint32_t numSamples;                           /* total number of elements in the matrix */
    int32_t totShift = 15 - shift;                 /* total shift to apply after scaling */
    uint32_t blkCnt;                               /* loop counters */
    arm_status status;                             /* status of matrix scaling     */
  
  #if defined (ARM_MATH_DSP)
  
    q15_t in1, in2, in3, in4;
    q31_t out1, out2, out3, out4;
    q31_t inA1, inA2;
  
  #endif //     #if defined (ARM_MATH_DSP)
  
  #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 >> 2;
  
      /* 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 */
        /* Scale, saturate and then store the results in the destination buffer. */
        /* Reading 2 inputs from memory */
        inA1 = _SIMD32_OFFSET(pIn);
        inA2 = _SIMD32_OFFSET(pIn + 2);
  
        /* C = A * scale */
        /* Scale the inputs and then store the 2 results in the destination buffer
         * in single cycle by packing the outputs */
        out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract);
        out2 = (q31_t) ((q15_t) inA1 * scaleFract);
        out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract);
        out4 = (q31_t) ((q15_t) inA2 * scaleFract);
  
        out1 = out1 >> totShift;
        inA1 = _SIMD32_OFFSET(pIn + 4);
        out2 = out2 >> totShift;
        inA2 = _SIMD32_OFFSET(pIn + 6);
        out3 = out3 >> totShift;
        out4 = out4 >> totShift;
  
        in1 = (q15_t) (__SSAT(out1, 16));
        in2 = (q15_t) (__SSAT(out2, 16));
        in3 = (q15_t) (__SSAT(out3, 16));
        in4 = (q15_t) (__SSAT(out4, 16));
  
        _SIMD32_OFFSET(pOut) = __PKHBT(in2, in1, 16);
        _SIMD32_OFFSET(pOut + 2) = __PKHBT(in4, in3, 16);
  
        /* 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. */
        *pOut++ =
          (q15_t) (__SSAT(((q31_t) (*pIn++) * scaleFract) >> totShift, 16));
  
        /* 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
   */
  