252 lines
6.9 KiB
C
252 lines
6.9 KiB
C
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/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_shift_q15.c
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* Description: Shifts the elements of a Q15 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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@addtogroup BasicShift
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@{
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*/
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/**
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@brief Shifts the elements of a Q15 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 each 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 Q15 range [0x8000 0x7FFF] 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_q15(
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const q15_t * pSrc,
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int8_t shiftBits,
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q15_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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q15x8_t vecSrc;
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q15x8_t vecDst;
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/* Compute 8 outputs at a time */
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blkCnt = blockSize >> 3;
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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(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 += 8;
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pDst += 8;
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}
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/*
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* tail
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*/
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blkCnt = blockSize & 7;
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if (blkCnt > 0U)
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{
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mve_pred16_t p0 = vctp16q(blkCnt);
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vecSrc = vld1q(pSrc);
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vecDst = vqshlq_r(vecSrc, shiftBits);
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vstrhq_p(pDst, vecDst, p0);
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}
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}
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#else
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void arm_shift_q15(
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const q15_t * pSrc,
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int8_t shiftBits,
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q15_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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#if defined (ARM_MATH_DSP)
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q15_t in1, in2; /* Temporary input variables */
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#endif
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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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#if defined (ARM_MATH_DSP)
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/* read 2 samples from source */
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in1 = *pSrc++;
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in2 = *pSrc++;
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/* Shift the inputs and then store the results in the destination buffer. */
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#ifndef ARM_MATH_BIG_ENDIAN
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write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in1 << shiftBits), 16),
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__SSAT(((q31_t) in2 << shiftBits), 16), 16));
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#else
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write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in2 << shiftBits), 16),
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__SSAT(((q31_t) in1 << shiftBits), 16), 16));
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#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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/* read 2 samples from source */
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in1 = *pSrc++;
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in2 = *pSrc++;
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#ifndef ARM_MATH_BIG_ENDIAN
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write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in1 << shiftBits), 16),
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__SSAT(((q31_t) in2 << shiftBits), 16), 16));
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#else
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write_q15x2_ia (&pDst, __PKHBT(__SSAT(((q31_t) in2 << shiftBits), 16),
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__SSAT(((q31_t) in1 << shiftBits), 16), 16));
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#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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#else
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*pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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*pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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*pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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*pDst++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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#endif
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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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#if defined (ARM_MATH_DSP)
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/* read 2 samples from source */
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in1 = *pSrc++;
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in2 = *pSrc++;
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/* Shift the inputs and then store the results in the destination buffer. */
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#ifndef ARM_MATH_BIG_ENDIAN
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write_q15x2_ia (&pDst, __PKHBT((in1 >> -shiftBits),
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(in2 >> -shiftBits), 16));
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#else
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write_q15x2_ia (&pDst, __PKHBT((in2 >> -shiftBits),
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(in1 >> -shiftBits), 16));
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#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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/* read 2 samples from source */
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in1 = *pSrc++;
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in2 = *pSrc++;
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#ifndef ARM_MATH_BIG_ENDIAN
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write_q15x2_ia (&pDst, __PKHBT((in1 >> -shiftBits),
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(in2 >> -shiftBits), 16));
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#else
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write_q15x2_ia (&pDst, __PKHBT((in2 >> -shiftBits),
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(in1 >> -shiftBits), 16));
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#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
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#else
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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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#endif
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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++ = __SSAT(((q31_t) *pSrc++ << shiftBits), 16);
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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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