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162 lines
5.2 KiB
162 lines
5.2 KiB
/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*
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* $Date: 12. March 2014
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* $Revision: V1.4.4
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*
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* Project: CMSIS DSP Library
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* Title: arm_scale_q15.c
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*
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* Description: Multiplies a Q15 vector by a scalar.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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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#ifndef ARM_MATH_CM0_FAMILY
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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 /* #ifndef ARM_MATH_CM0_FAMILY */
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}
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/**
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* @} end of scale group
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*/
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