158 lines
4.1 KiB
C
158 lines
4.1 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: 27. January 2017
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* $Revision: V.1.5.1
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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) 2010-2017 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 scale Vector Scale
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*
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* Multiply a vector by a scalar value. For floating-point data, the algorithm used is:
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*
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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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*
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* In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by
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* a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.
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* The shift allows the gain of the scaling operation to exceed 1.0.
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* The algorithm used with fixed-point data is:
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*
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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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*
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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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*
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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 scale
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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 the vector
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* @return none.
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*/
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void arm_scale_f32(
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float32_t * pSrc,
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float32_t scale,
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float32_t * pDst,
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uint32_t blockSize)
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{
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uint32_t blkCnt; /* loop counter */
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#if defined (ARM_MATH_DSP)
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/* Run the below code for Cortex-M4 and Cortex-M3 */
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float32_t in1, in2, in3, in4; /* temporary variabels */
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/*loop Unrolling */
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blkCnt = blockSize >> 2U;
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/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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** a second loop below computes the remaining 1 to 3 samples. */
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while (blkCnt > 0U)
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{
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/* C = A * scale */
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/* Scale the input and then store the results in the destination buffer. */
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/* read input samples from source */
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in1 = *pSrc;
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in2 = *(pSrc + 1);
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/* multiply with scaling factor */
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in1 = in1 * scale;
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/* read input sample from source */
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in3 = *(pSrc + 2);
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/* multiply with scaling factor */
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in2 = in2 * scale;
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/* read input sample from source */
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in4 = *(pSrc + 3);
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/* multiply with scaling factor */
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in3 = in3 * scale;
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in4 = in4 * scale;
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/* store the result to destination */
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*pDst = in1;
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*(pDst + 1) = in2;
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*(pDst + 2) = in3;
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*(pDst + 3) = in4;
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/* update pointers to process next samples */
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pSrc += 4U;
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pDst += 4U;
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/* Decrement the loop counter */
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blkCnt--;
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}
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/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
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** No loop unrolling is used. */
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blkCnt = blockSize % 0x4U;
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#else
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/* Run the below code for Cortex-M0 */
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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_DSP) */
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while (blkCnt > 0U)
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{
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/* C = A * scale */
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/* Scale the input and then store the result in the destination buffer. */
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*pDst++ = (*pSrc++) * scale;
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/* Decrement the 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 scale group
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*/
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