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150 lines
4.2 KiB
150 lines
4.2 KiB
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_scale_q15.c
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* Description: Multiplies a Q15 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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* @addtogroup scale
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* @{
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*/
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/**
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* @brief Multiplies a Q15 vector by a scalar.
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* @param[in] *pSrc points to the input vector
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* @param[in] scaleFract fractional portion of the scale value
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* @param[in] shift number of bits to shift the result by
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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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* <b>Scaling and Overflow Behavior:</b>
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* \par
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* The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
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* These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
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*/
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void arm_scale_q15(
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q15_t * pSrc,
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q15_t scaleFract,
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int8_t shift,
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q15_t * pDst,
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uint32_t blockSize)
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{
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int8_t kShift = 15 - shift; /* shift to apply after scaling */
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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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q15_t in1, in2, in3, in4;
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q31_t inA1, inA2; /* Temporary variables */
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q31_t out1, out2, out3, out4;
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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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/* Reading 2 inputs from memory */
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inA1 = *__SIMD32(pSrc)++;
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inA2 = *__SIMD32(pSrc)++;
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/* C = A * scale */
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/* Scale the inputs and then store the 2 results in the destination buffer
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* in single cycle by packing the outputs */
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out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract);
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out2 = (q31_t) ((q15_t) inA1 * scaleFract);
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out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract);
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out4 = (q31_t) ((q15_t) inA2 * scaleFract);
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/* apply shifting */
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out1 = out1 >> kShift;
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out2 = out2 >> kShift;
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out3 = out3 >> kShift;
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out4 = out4 >> kShift;
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/* saturate the output */
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in1 = (q15_t) (__SSAT(out1, 16));
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in2 = (q15_t) (__SSAT(out2, 16));
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in3 = (q15_t) (__SSAT(out3, 16));
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in4 = (q15_t) (__SSAT(out4, 16));
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/* store the result to destination */
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*__SIMD32(pDst)++ = __PKHBT(in2, in1, 16);
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*__SIMD32(pDst)++ = __PKHBT(in4, in3, 16);
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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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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++ = (q15_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 16));
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/* Decrement the loop counter */
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blkCnt--;
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}
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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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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++ = (q15_t) (__SSAT(((q31_t) * pSrc++ * scaleFract) >> kShift, 16));
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/* Decrement the loop counter */
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blkCnt--;
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}
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#endif /* #if defined (ARM_MATH_DSP) */
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}
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/**
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* @} end of scale group
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*/
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