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

* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    

*    

* $Date:        19. March 2015

* $Revision:    V.1.4.5

*    

* Project:          CMSIS DSP Library    

* Title:                arm_scale_q31.c    

*    

* Description:  Multiplies a Q31 vector by a scalar.    

*    

* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0

*  

* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions

* are met:

*   - Redistributions of source code must retain the above copyright

*     notice, this list of conditions and the following disclaimer.

*   - Redistributions in binary form must reproduce the above copyright

*     notice, this list of conditions and the following disclaimer in

*     the documentation and/or other materials provided with the

*     distribution.

*   - Neither the name of ARM LIMITED nor the names of its contributors

*     may be used to endorse or promote products derived from this

*     software without specific prior written permission.

*

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

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

#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;

#ifndef ARM_MATH_CM0_FAMILY

/* 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 /* #ifndef ARM_MATH_CM0_FAMILY */

  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      

 */