138 lines
3.9 KiB
C
138 lines
3.9 KiB
C
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/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_scale_q7.c
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* Description: Multiplies a Q7 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 Q7 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 1.7 format.
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* These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.
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*/
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void arm_scale_q7(
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q7_t * pSrc,
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q7_t scaleFract,
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int8_t shift,
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q7_t * pDst,
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uint32_t blockSize)
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{
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int8_t kShift = 7 - 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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q7_t in1, in2, in3, in4, out1, out2, out3, out4; /* Temporary variables to store input & output */
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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 4 inputs from memory */
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in1 = *pSrc++;
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in2 = *pSrc++;
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in3 = *pSrc++;
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in4 = *pSrc++;
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/* C = A * scale */
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/* Scale the inputs and then store the results in the temporary variables. */
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out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8));
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out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8));
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out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8));
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out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8));
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/* Packing the individual outputs into 32bit and storing in
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* destination buffer in single write */
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*__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
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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++ = (q7_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 8));
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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++ = (q7_t) (__SSAT((((q15_t) * pSrc++ * scaleFract) >> kShift), 8));
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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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