160 lines
3.9 KiB
C
160 lines
3.9 KiB
C
/* ----------------------------------------------------------------------
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_scale_f32.c
|
|
* Description: Multiplies a floating-point vector by a scalar
|
|
*
|
|
* $Date: 18. March 2019
|
|
* $Revision: V1.6.0
|
|
*
|
|
* Target Processor: Cortex-M cores
|
|
* -------------------------------------------------------------------- */
|
|
/*
|
|
* Copyright (C) 2010-2019 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 BasicScale 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 BasicScale
|
|
@{
|
|
*/
|
|
|
|
/**
|
|
@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 each vector
|
|
@return none
|
|
*/
|
|
|
|
void arm_scale_f32(
|
|
const float32_t *pSrc,
|
|
float32_t scale,
|
|
float32_t *pDst,
|
|
uint32_t blockSize)
|
|
{
|
|
uint32_t blkCnt; /* Loop counter */
|
|
#if defined(ARM_MATH_NEON_EXPERIMENTAL)
|
|
float32x4_t vec1;
|
|
float32x4_t res;
|
|
|
|
/* Compute 4 outputs at a time */
|
|
blkCnt = blockSize >> 2U;
|
|
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* C = A * scale */
|
|
|
|
/* Scale the input and then store the results in the destination buffer. */
|
|
vec1 = vld1q_f32(pSrc);
|
|
res = vmulq_f32(vec1, vdupq_n_f32(scale));
|
|
vst1q_f32(pDst, res);
|
|
|
|
/* Increment pointers */
|
|
pSrc += 4;
|
|
pDst += 4;
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Tail */
|
|
blkCnt = blockSize & 0x3;
|
|
|
|
#else
|
|
#if defined (ARM_MATH_LOOPUNROLL)
|
|
|
|
/* Loop unrolling: Compute 4 outputs at a time */
|
|
blkCnt = blockSize >> 2U;
|
|
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* C = A * scale */
|
|
|
|
/* Scale input and store result in destination buffer. */
|
|
*pDst++ = (*pSrc++) * scale;
|
|
|
|
*pDst++ = (*pSrc++) * scale;
|
|
|
|
*pDst++ = (*pSrc++) * scale;
|
|
|
|
*pDst++ = (*pSrc++) * scale;
|
|
|
|
/* Decrement loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Loop unrolling: Compute remaining outputs */
|
|
blkCnt = blockSize % 0x4U;
|
|
|
|
#else
|
|
|
|
/* Initialize blkCnt with number of samples */
|
|
blkCnt = blockSize;
|
|
|
|
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
|
|
#endif /* #if defined(ARM_MATH_NEON_EXPERIMENTAL) */
|
|
|
|
while (blkCnt > 0U)
|
|
{
|
|
/* C = A * scale */
|
|
|
|
/* Scale input and store result in destination buffer. */
|
|
*pDst++ = (*pSrc++) * scale;
|
|
|
|
/* Decrement loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
}
|
|
|
|
/**
|
|
@} end of BasicScale group
|
|
*/
|