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/* ----------------------------------------------------------------------

 * Project:      CMSIS DSP Library

 * Title:        arm_scale_q31.c

 * Description:  Multiplies a Q31 vector 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 groupMath

 */

/**

 * @addtogroup scale

 * @{

 */

/**

 * @brief Multiplies a Q31 vector by a scalar.

 * @param[in]       *pSrc points to the input vector

 * @param[in]       scaleFract fractional portion of the scale value

 * @param[in]       shift number of bits to shift the result by

 * @param[out]      *pDst points to the output vector

 * @param[in]       blockSize number of samples in the vector

 * @return none.

 *

 * <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.

 */

void arm_scale_q31(

  q31_t * pSrc,

  q31_t scaleFract,

  int8_t shift,

  q31_t * pDst,

  uint32_t blockSize)

{

  int8_t kShift = shift + 1;                     /* Shift to apply after scaling */

  int8_t sign = (kShift & 0x80);

  uint32_t blkCnt;                               /* loop counter */

  q31_t in, out;

#if defined (ARM_MATH_DSP)

/* Run the below code for Cortex-M4 and Cortex-M3 */

  q31_t in1, in2, in3, in4;                      /* temporary input variables */

  q31_t out1, out2, out3, out4;                  /* temporary output variabels */

  /*loop Unrolling */

  blkCnt = blockSize >> 2U;

  if (sign == 0U)

  {

    /* 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)

    {

      /* read four inputs from source */

      in1 = *pSrc;

      in2 = *(pSrc + 1);

      in3 = *(pSrc + 2);

      in4 = *(pSrc + 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 << kShift;

      out2 = in2 << kShift;

      /* saturate the results. */

      if (in1 != (out1 >> kShift))

        out1 = 0x7FFFFFFF ^ (in1 >> 31);

      if (in2 != (out2 >> kShift))

        out2 = 0x7FFFFFFF ^ (in2 >> 31);

      out3 = in3 << kShift;

      out4 = in4 << kShift;

      *pDst = out1;

      *(pDst + 1) = out2;

      if (in3 != (out3 >> kShift))

        out3 = 0x7FFFFFFF ^ (in3 >> 31);

      if (in4 != (out4 >> kShift))

        out4 = 0x7FFFFFFF ^ (in4 >> 31);

      /* Store result destination */

      *(pDst + 2) = out3;

      *(pDst + 3) = out4;

      /* Update pointers to process next sampels */

      pSrc += 4U;

      pDst += 4U;

      /* Decrement the loop counter */

      blkCnt--;

    }

  }

  else

  {

    /* 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)

    {

      /* read four inputs from source */

      in1 = *pSrc;

      in2 = *(pSrc + 1);

      in3 = *(pSrc + 2);

      in4 = *(pSrc + 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 >> -kShift;

      out2 = in2 >> -kShift;

      out3 = in3 >> -kShift;

      out4 = in4 >> -kShift;

      /* Store result destination */

      *pDst = out1;

      *(pDst + 1) = out2;

      *(pDst + 2) = out3;

      *(pDst + 3) = out4;

      /* Update pointers to process next sampels */

      pSrc += 4U;

      pDst += 4U;

      /* Decrement the loop counter */

      blkCnt--;

    }

  }

  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.

   ** No loop unrolling is used. */

  blkCnt = blockSize % 0x4U;

#else

  /* Run the below code for Cortex-M0 */

  /* Initialize blkCnt with number of samples */

  blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_DSP) */

  if (sign == 0)

  {

          while (blkCnt > 0U)

          {

                /* C = A * scale */

                /* Scale the input and then store the result in the destination buffer. */

                in = *pSrc++;

                in = ((q63_t) in * scaleFract) >> 32;

                out = in << kShift;

                if (in != (out >> kShift))

                        out = 0x7FFFFFFF ^ (in >> 31);

                *pDst++ = out;

                /* Decrement the loop counter */

                blkCnt--;

          }

  }

  else

  {

          while (blkCnt > 0U)

          {

                /* C = A * scale */

                /* Scale the input and then store the result in the destination buffer. */

                in = *pSrc++;

                in = ((q63_t) in * scaleFract) >> 32;

                out = in >> -kShift;

                *pDst++ = out;

                /* Decrement the loop counter */

                blkCnt--;

          }

  }

}

/**

 * @} end of scale group

 */