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2 mjames 1 
/* ----------------------------------------------------------------------    
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
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*    
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* $Date:        19. March 2015
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* $Revision:    V.1.4.5
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*    
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* Project:          CMSIS DSP Library    
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* Title:                arm_abs_q7.c    
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*    
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* Description:  Q7 vector absolute value.    
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*    
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*  
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*   - Redistributions of source code must retain the above copyright
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*     notice, this list of conditions and the following disclaimer.
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*   - Redistributions in binary form must reproduce the above copyright
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*     notice, this list of conditions and the following disclaimer in
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*     the documentation and/or other materials provided with the
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*     distribution.
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*   - Neither the name of ARM LIMITED nor the names of its contributors
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*     may be used to endorse or promote products derived from this
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*     software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 BasicAbs        
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 * @{        
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 */
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/**        
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 * @brief Q7 vector absolute value.        
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 * @param[in]       *pSrc points to the input buffer        
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 * @param[out]      *pDst points to the output buffer        
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 * @param[in]       blockSize number of samples in each vector        
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 * @return none.        
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 *    
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 * \par Conditions for optimum performance    
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 *  Input and output buffers should be aligned by 32-bit    
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 *    
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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_abs_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 in;                                       /* Input value1 */
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#ifndef ARM_MATH_CM0_FAMILY
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  /* Run the below code for Cortex-M4 and Cortex-M3 */
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  q31_t in1, in2, in3, in4;                      /* temporary input variables */
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  q31_t out1, out2, out3, out4;                  /* temporary output variables */
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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 inputs */
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    in1 = (q31_t) * pSrc;
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    in2 = (q31_t) * (pSrc + 1);
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    in3 = (q31_t) * (pSrc + 2);
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    /* find absolute value */
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    out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
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    /* read input */
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    in4 = (q31_t) * (pSrc + 3);
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    /* find absolute value */
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    out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
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    /* store result to destination */
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    *pDst = (q7_t) out1;
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    /* find absolute value */
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    out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
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    /* find absolute value */
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    out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
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    /* store result to destination */
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    *(pDst + 1) = (q7_t) out2;
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    /* store result to destination */
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    *(pDst + 2) = (q7_t) out3;
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    /* store result to destination */
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    *(pDst + 3) = (q7_t) out4;
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    /* update pointers to process next samples */
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    pSrc += 4u;
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    pDst += 4u;
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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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#else
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  /* Run the below code for Cortex-M0 */
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  blkCnt = blockSize;
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5 mjames 139 
#endif /* #define ARM_MATH_CM0_FAMILY */
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  while(blkCnt > 0u)
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  {
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    /* C = |A| */
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    /* Read the input */
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    in = *pSrc++;
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    /* Store the Absolute result in the destination buffer */
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    *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
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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 BasicAbs group        
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 */