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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_negate_q7.c
* Description: Negates Q7 vectors
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "arm_math.h"
/**
@ingroup groupMath
*/
/**
@addtogroup BasicNegate
@{
*/
/**
@brief Negates the elements of a Q7 vector.
@param[in] pSrc points to the input vector.
@param[out] pDst points to the output vector.
@param[in] blockSize number of samples in each vector.
@return none
@par Scaling and Overflow Behavior
The function uses saturating arithmetic.
The Q7 value -1 (0x80) is saturated to the maximum allowable positive value 0x7F.
*/
void arm_negate_q7(
const q7_t * pSrc,
q7_t * pDst,
uint32_t blockSize)
{
uint32_t blkCnt; /* Loop counter */
q7_t in; /* Temporary input variable */
#if defined (ARM_MATH_LOOPUNROLL)
#if defined (ARM_MATH_DSP)
q31_t in1; /* Temporary input variable */
#endif
/* Loop unrolling: Compute 4 outputs at a time */
blkCnt = blockSize >> 2U;
while (blkCnt > 0U)
{
/* C = -A */
#if defined (ARM_MATH_DSP)
/* Negate and store result in destination buffer (4 samples at a time). */
in1 = read_q7x4_ia ((q7_t **) &pSrc);
write_q7x4_ia (&pDst, __QSUB8(0, in1));
#else
in = *pSrc++;
*pDst++ = (in == (q7_t) 0x80) ? (q7_t) 0x7f : -in;
in = *pSrc++;
*pDst++ = (in == (q7_t) 0x80) ? (q7_t) 0x7f : -in;
in = *pSrc++;
*pDst++ = (in == (q7_t) 0x80) ? (q7_t) 0x7f : -in;
in = *pSrc++;
*pDst++ = (in == (q7_t) 0x80) ? (q7_t) 0x7f : -in;
#endif
/* Decrement loop counter */
blkCnt--;
}
/* Loop unrolling: Compute remaining outputs */
blkCnt = blockSize % 0x4U;
#else
/* Initialize blkCnt with number of samples */
blkCnt = blockSize;
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
while (blkCnt > 0U)
{
/* C = -A */
/* Negate and store result in destination buffer. */
in = *pSrc++;
#if defined (ARM_MATH_DSP)
*pDst++ = (q7_t) __QSUB(0, in);
#else
*pDst++ = (in == (q7_t) 0x80) ? (q7_t) 0x7f : -in;
#endif
/* Decrement loop counter */
blkCnt--;
}
}
/**
@} end of BasicNegate group
*/
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