126 lines
3.2 KiB
C
126 lines
3.2 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_scale_f32.c
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* Description: Multiplies a floating-point vector by a scalar
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*
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* $Date: 18. March 2019
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* $Revision: V1.6.0
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "arm_math.h"
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/**
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@ingroup groupMath
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*/
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/**
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@defgroup BasicScale Vector Scale
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Multiply a vector by a scalar value. For floating-point data, the algorithm
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used is:
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<pre>
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pDst[n] = pSrc[n] * scale, 0 <= n < blockSize.
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</pre>
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In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is
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represented by a fractional multiplication <code>scaleFract</code> and an
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arithmetic shift <code>shift</code>. The shift allows the gain of the scaling
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operation to exceed 1.0. The algorithm used with fixed-point data is:
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<pre>
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pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize.
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</pre>
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The overall scale factor applied to the fixed-point data is
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<pre>
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scale = scaleFract * 2^shift.
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</pre>
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The functions support in-place computation allowing the source and destination
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pointers to reference the same memory buffer.
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*/
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/**
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@addtogroup BasicScale
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@{
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*/
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/**
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@brief Multiplies a floating-point vector by a scalar.
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@param[in] pSrc points to the input vector
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@param[in] scale scale factor to be applied
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@param[out] pDst points to the output vector
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@param[in] blockSize number of samples in each vector
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@return none
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*/
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void arm_scale_f32(const float32_t *pSrc, float32_t scale, float32_t *pDst,
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uint32_t blockSize) {
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uint32_t blkCnt; /* Loop counter */
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#if defined(ARM_MATH_LOOPUNROLL)
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/* Loop unrolling: Compute 4 outputs at a time */
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blkCnt = blockSize >> 2U;
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while (blkCnt > 0U) {
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/* C = A * scale */
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/* Scale input and store result in destination buffer. */
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*pDst++ = (*pSrc++) * scale;
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*pDst++ = (*pSrc++) * scale;
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*pDst++ = (*pSrc++) * scale;
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*pDst++ = (*pSrc++) * scale;
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/* Decrement loop counter */
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blkCnt--;
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}
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/* Loop unrolling: Compute remaining outputs */
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blkCnt = blockSize % 0x4U;
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#else
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/* Initialize blkCnt with number of samples */
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blkCnt = blockSize;
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#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
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while (blkCnt > 0U) {
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/* C = A * scale */
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/* Scale input and store result in destination buffer. */
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*pDst++ = (*pSrc++) * scale;
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/* Decrement loop counter */
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blkCnt--;
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}
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}
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/**
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@} end of BasicScale group
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*/
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