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/* ----------------------------------------------------------------------
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* Copyright (C) 2010 ARM Limited. All rights reserved.
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*
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* $Date: 29. November 2010
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* $Revision: V1.0.3
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*
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* Project: CMSIS DSP Library
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* Title: arm_negate_q7.c
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*
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* Description: Negates Q7 vectors.
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*
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* Target Processor: Cortex-M4/Cortex-M3
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*
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* Version 1.0.3 2010/11/29
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* Re-organized the CMSIS folders and updated documentation.
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*
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* Version 1.0.2 2010/11/11
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* Documentation updated.
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*
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* Version 1.0.1 2010/10/05
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* Production release and review comments incorporated.
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*
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* Version 1.0.0 2010/09/20
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* Production release and review comments incorporated.
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*
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* Version 0.0.7 2010/06/10
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* Misra-C changes done
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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 negate
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* @{
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*/
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/**
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* @brief Negates the elements of a Q7 vector.
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* @param *pSrc points to the input vector
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* @param *pDst points to the output vector
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* @param 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 function uses saturating arithmetic.
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* The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
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*/
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void arm_negate_q7(
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q7_t * pSrc,
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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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q7_t in1; /* Input value1 */
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q7_t in2; /* Input value2 */
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q7_t in3; /* Input value3 */
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q7_t in4; /* Input value4 */
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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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/* C = ~A */
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/* Read four 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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/* Store the Negated results in the destination buffer in a single cycle by packing the results */
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*__SIMD32(pDst)++ =
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__PACKq7(__SSAT(-in1, 8), __SSAT(-in2, 8), __SSAT(-in3, 8),
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__SSAT(-in4, 8));
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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 */
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/* Negate and then store the results in the destination buffer. */
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*pDst++ = __SSAT(-*pSrc++, 8);
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/* Decrement the loop counter */
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blkCnt--;
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}
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}
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/**
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* @} end of negate group
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*/
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