text: /* ----------------------------------------------------------------------    
  * Copyright (C) 2010 ARM Limited. All rights reserved.    
  *    
  * $Date: 14/06/07 1:56a $Revision: 	V1.1.0  
  *    
  * Project: 	    CMSIS DSP Library    
  * Title:		arm_negate_q15.c    
  *    
  * Description:	Negates Q15 vectors.    
  *    
  * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  *  
  * Version 1.1.0 2012/02/15 
  *    Updated with more optimizations, bug fixes and minor API changes.  
  *   
  * Version 1.0.10 2011/7/15  
  *    Big Endian support added and Merged M0 and M3/M4 Source code.   
  *    
  * Version 1.0.3 2010/11/29   
  *    Re-organized the CMSIS folders and updated documentation.    
  *     
  * Version 1.0.2 2010/11/11    
  *    Documentation updated.     
  *    
  * Version 1.0.1 2010/10/05     
  *    Production release and review comments incorporated.    
  *    
  * Version 1.0.0 2010/09/20     
  *    Production release and review comments incorporated.    
  *    
  * Version 0.0.7  2010/06/10     
  *    Misra-C changes done    
  * -------------------------------------------------------------------- */
  #include "arm_math.h"
  
  /**        
   * @ingroup groupMath        
   */
  
  /**        
   * @addtogroup negate        
   * @{        
   */
  
  /**        
   * @brief  Negates the elements of a Q15 vector.        
   * @param[in]  *pSrc points to the input vector        
   * @param[out]  *pDst points to the output vector        
   * @param[in]  blockSize number of samples in the vector        
   * @return none.        
   *    
   * \par Conditions for optimum performance    
   *  Input and output buffers should be aligned by 32-bit    
   *    
   *        
   * <b>Scaling and Overflow Behavior:</b>        
   * \par        
   * The function uses saturating arithmetic.        
   * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.        
   */
  
  void arm_negate_q15(
    q15_t * pSrc,
    q15_t * pDst,
    uint32_t blockSize)
  {
    uint32_t blkCnt;                               /* loop counter */
    q15_t in;
  
  #ifndef ARM_MATH_CM0
  
  /* Run the below code for Cortex-M4 and Cortex-M3 */
  
    q31_t in1, in2;                                /* Temporary variables */
  
  
    /*loop Unrolling */
    blkCnt = blockSize >> 2u;
  
    /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.        
     ** a second loop below computes the remaining 1 to 3 samples. */
    while(blkCnt > 0u)
    {
      /* C = -A */
      /* Read two inputs at a time */
      in1 = _SIMD32_OFFSET(pSrc);
      in2 = _SIMD32_OFFSET(pSrc + 2);
  
      /* negate two samples at a time */
      in1 = __QSUB16(0, in1);
  
      /* negate two samples at a time */
      in2 = __QSUB16(0, in2);
  
      /* store the result to destination 2 samples at a time */
      _SIMD32_OFFSET(pDst) = in1;
      /* store the result to destination 2 samples at a time */
      _SIMD32_OFFSET(pDst + 2) = in2;
  
  
      /* update pointers to process next samples */
      pSrc += 4u;
      pDst += 4u;
  
      /* Decrement the loop counter */
      blkCnt--;
    }
  
    /* If the blockSize is not a multiple of 4, compute any remaining output samples here.        
     ** No loop unrolling is used. */
    blkCnt = blockSize % 0x4u;
  
  #else
  
    /* Run the below code for Cortex-M0 */
  
    /* Initialize blkCnt with number of samples */
    blkCnt = blockSize;
  
  #endif /* #ifndef ARM_MATH_CM0 */
  
    while(blkCnt > 0u)
    {
      /* C = -A */
      /* Negate and then store the result in the destination buffer. */
      in = *pSrc++;
      *pDst++ = (in == (q15_t) 0x8000) ? 0x7fff : -in;
  
      /* Decrement the loop counter */
      blkCnt--;
    }
  }
  
  /**        
   * @} end of negate group        
   */
  