175 lines
4.8 KiB
C
175 lines
4.8 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_shift_q7.c
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* Description: Processing function for the Q7 Shifting
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*
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* $Date: 18. March 2019
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* $Revision: V1.6.0
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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) 2010-2019 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 BasicShift
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@{
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*/
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/**
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@brief Shifts the elements of a Q7 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 onditions for optimum performance
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Input and output buffers should be aligned by 32-bit
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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 Q7 range [0x80 0x7F] are saturated.
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*/
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void arm_shift_q7(
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const q7_t * pSrc,
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int8_t shiftBits,
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q7_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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q7_t in1, in2, in3, in4; /* 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 4 inputs */
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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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/* Pack and store result in destination buffer (in single write) */
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write_q7x4_ia (&pDst, __PACKq7(__SSAT((in1 << shiftBits), 8),
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__SSAT((in2 << shiftBits), 8),
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__SSAT((in3 << shiftBits), 8),
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__SSAT((in4 << shiftBits), 8) ));
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#else
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*pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
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*pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
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*pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
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*pDst++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
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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 4 inputs */
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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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/* Pack and store result in destination buffer (in single write) */
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write_q7x4_ia (&pDst, __PACKq7((in1 >> -shiftBits),
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(in2 >> -shiftBits),
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(in3 >> -shiftBits),
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(in4 >> -shiftBits) ));
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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++ = (q7_t) __SSAT(((q15_t) *pSrc++ << shiftBits), 8);
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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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/**
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@} end of BasicShift group
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*/
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