File content as of revision 1:fdd22bb7aa52:

/* ----------------------------------------------------------------------    
* Copyright (C) 2010 ARM Limited. All rights reserved.    
*    
* $Date:        15. February 2012  
* $Revision:     V1.1.0  
*    
* Project:         CMSIS DSP Library    
* Title:        arm_negate_q7.c    
*    
* Description:    Negates Q7 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 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 the vector    
 * @return none.    
 *    
 * <b>Scaling and Overflow Behavior:</b>    
 * \par    
 * The function uses saturating arithmetic.    
 * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.    
 */

void arm_negate_q7(
  q7_t * pSrc,
  q7_t * pDst,
  uint32_t blockSize)
{
  uint32_t blkCnt;                               /* loop counter */
  q7_t in;

#ifndef ARM_MATH_CM0

/* Run the below code for Cortex-M4 and Cortex-M3 */
  q31_t input;                                   /* Input values1-4 */
  q31_t zero = 0x00000000;


  /*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 four inputs */
    input = *__SIMD32(pSrc)++;

    /* Store the Negated results in the destination buffer in a single cycle by packing the results */
    *__SIMD32(pDst)++ = __QSUB8(zero, input);

    /* 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 results in the destination buffer. */ \
      in = *pSrc++;
    *pDst++ = (in == (q7_t) 0x80) ? 0x7f : -in;

    /* Decrement the loop counter */
    blkCnt--;
  }
}

/**    
 * @} end of negate group    
 */