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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_scale_f32.c
* Description: Multiplies a floating-point 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
*/
/**
* @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 */
#if defined (ARM_MATH_DSP)
/* 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 /* #if defined (ARM_MATH_DSP) */
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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