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/* ----------------------------------------------------------------------
* Copyright (C) 2010-2013 ARM Limited. All rights reserved.
*
* $Date: 17. January 2013
* $Revision: V1.4.1
*
* Project: CMSIS DSP Library
* Title: arm_scale_f32.c
*
* Description: Multiplies a floating-point 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
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* ---------------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupMath
*/
/**
* @defgroup scale Vector Scale
*
* Multiply a vector by a scalar value. For floating-point data, the algorithm used is:
*
* <pre>
* pDst[n] = pSrc[n] * scale, 0 <= n < blockSize.
* </pre>
*
* In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by
* a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.
* The shift allows the gain of the scaling operation to exceed 1.0.
* The algorithm used with fixed-point data is:
*
* <pre>
* pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize.
* </pre>
*
* The overall scale factor applied to the fixed-point data is
* <pre>
* scale = scaleFract * 2^shift.
* </pre>
*
* The functions support in-place computation allowing the source and destination
* pointers to reference the same memory buffer.
*/
/**
* @addtogroup scale
* @{
*/
/**
* @brief Multiplies a floating-point vector by a scalar.
* @param[in] *pSrc points to the input vector
* @param[in] scale scale factor to be applied
* @param[out] *pDst points to the output vector
* @param[in] blockSize number of samples in the vector
* @return none.
*/
void arm_scale_f32(
float32_t * pSrc,
float32_t scale,
float32_t * pDst,
uint32_t blockSize)
{
uint32_t blkCnt; /* loop counter */
#ifndef ARM_MATH_CM0_FAMILY
/* Run the below code for Cortex-M4 and Cortex-M3 */
float32_t in1, in2, in3, in4; /* temporary variabels */
/*loop Unrolling */
blkCnt = blockSize >> 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 = A * scale */
/* Scale the input and then store the results in the destination buffer. */
/* read input samples from source */
in1 = *pSrc;
in2 = *(pSrc + 1);
/* multiply with scaling factor */
in1 = in1 * scale;
/* read input sample from source */
in3 = *(pSrc + 2);
/* multiply with scaling factor */
in2 = in2 * scale;
/* read input sample from source */
in4 = *(pSrc + 3);
/* multiply with scaling factor */
in3 = in3 * scale;
in4 = in4 * scale;
/* store the result to destination */
*pDst = in1;
*(pDst + 1) = in2;
*(pDst + 2) = in3;
*(pDst + 3) = in4;
/* update pointers to process next samples */
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 */
while(blkCnt > 0u)
{
/* C = A * scale */
/* Scale the input and then store the result in the destination buffer. */
*pDst++ = (*pSrc++) * scale;
/* Decrement the loop counter */
blkCnt--;
}
}
/**
* @} end of scale group
*/
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