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Drivers/CMSIS/DSP/Source/BasicMathFunctions/arm_shift_q31.c
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232
Drivers/CMSIS/DSP/Source/BasicMathFunctions/arm_shift_q31.c
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/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_shift_q31.c
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* Description: Shifts the elements of a Q31 vector by a specified number of bits
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*
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* $Date: 23 April 2021
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* $Revision: V1.9.0
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*
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* Target Processor: Cortex-M and Cortex-A cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2021 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 "dsp/basic_math_functions.h"
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/**
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@ingroup groupMath
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*/
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/**
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@defgroup BasicShift Vector Shift
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Shifts the elements of a fixed-point vector by a specified number of bits.
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There are separate functions for Q7, Q15, and Q31 data types.
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The underlying algorithm used is:
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<pre>
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pDst[n] = pSrc[n] << shift, 0 <= n < blockSize.
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</pre>
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If <code>shift</code> is positive then the elements of the vector are shifted to the left.
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If <code>shift</code> is negative then the elements of the vector are shifted to the right.
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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 BasicShift
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@{
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*/
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/**
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@brief Shifts the elements of a Q31 vector a specified number of bits.
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@param[in] pSrc points to the input vector
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@param[in] shiftBits number of bits to shift. A positive value shifts left; a negative value shifts right.
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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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@par Scaling and Overflow Behavior
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The function uses saturating arithmetic.
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Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] are saturated.
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*/
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#if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
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#include "arm_helium_utils.h"
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void arm_shift_q31(
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const q31_t * pSrc,
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int8_t shiftBits,
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q31_t * pDst,
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uint32_t blockSize)
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{
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uint32_t blkCnt; /* loop counters */
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q31x4_t vecSrc;
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q31x4_t vecDst;
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/* Compute 4 outputs at a time */
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blkCnt = blockSize >> 2;
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while (blkCnt > 0U)
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{
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/*
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* C = A (>> or <<) shiftBits
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* Shift the input and then store the result in the destination buffer.
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*/
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vecSrc = vld1q((q31_t const *) pSrc);
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vecDst = vqshlq_r(vecSrc, shiftBits);
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vst1q(pDst, vecDst);
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/*
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* Decrement the blockSize loop counter
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*/
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blkCnt--;
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/*
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* advance vector source and destination pointers
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*/
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pSrc += 4;
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pDst += 4;
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}
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/*
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* tail
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*/
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blkCnt = blockSize & 3;
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if (blkCnt > 0U)
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{
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mve_pred16_t p0 = vctp32q(blkCnt);
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vecSrc = vld1q((q31_t const *) pSrc);
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vecDst = vqshlq_r(vecSrc, shiftBits);
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vstrwq_p(pDst, vecDst, p0);
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}
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}
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#else
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void arm_shift_q31(
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const q31_t * pSrc,
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int8_t shiftBits,
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q31_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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uint8_t sign = (shiftBits & 0x80); /* Sign of shiftBits */
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#if defined (ARM_MATH_LOOPUNROLL)
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q31_t in, out; /* Temporary variables */
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/* Loop unrolling: Compute 4 outputs at a time */
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blkCnt = blockSize >> 2U;
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/* If the shift value is positive then do right shift else left shift */
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if (sign == 0U)
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{
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while (blkCnt > 0U)
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{
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/* C = A << shiftBits */
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/* Shift input and store result in destination buffer. */
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in = *pSrc++;
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out = in << shiftBits;
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if (in != (out >> shiftBits))
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out = 0x7FFFFFFF ^ (in >> 31);
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*pDst++ = out;
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in = *pSrc++;
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out = in << shiftBits;
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if (in != (out >> shiftBits))
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out = 0x7FFFFFFF ^ (in >> 31);
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*pDst++ = out;
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in = *pSrc++;
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out = in << shiftBits;
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if (in != (out >> shiftBits))
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out = 0x7FFFFFFF ^ (in >> 31);
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*pDst++ = out;
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in = *pSrc++;
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out = in << shiftBits;
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if (in != (out >> shiftBits))
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out = 0x7FFFFFFF ^ (in >> 31);
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*pDst++ = out;
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/* Decrement loop counter */
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blkCnt--;
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}
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}
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else
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{
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while (blkCnt > 0U)
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{
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/* C = A >> shiftBits */
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/* Shift input and store results in destination buffer. */
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*pDst++ = (*pSrc++ >> -shiftBits);
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*pDst++ = (*pSrc++ >> -shiftBits);
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*pDst++ = (*pSrc++ >> -shiftBits);
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*pDst++ = (*pSrc++ >> -shiftBits);
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/* Decrement loop counter */
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blkCnt--;
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}
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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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/* If the shift value is positive then do right shift else left shift */
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if (sign == 0U)
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{
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while (blkCnt > 0U)
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{
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/* C = A << shiftBits */
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/* Shift input and store result in destination buffer. */
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*pDst++ = clip_q63_to_q31((q63_t) *pSrc++ << shiftBits);
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/* Decrement loop counter */
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blkCnt--;
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}
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}
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else
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{
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while (blkCnt > 0U)
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{
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/* C = A >> shiftBits */
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/* Shift input and store result in destination buffer. */
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*pDst++ = (*pSrc++ >> -shiftBits);
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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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#endif /* defined(ARM_MATH_MVEI) */
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/**
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@} end of BasicShift group
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*/
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