text: /* ----------------------------------------------------------------------    
  * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  *    
  * $Date:        12. March 2014
  * $Revision: 	V1.4.4
  *    
  * Project: 	    CMSIS DSP Library    
  * Title:		arm_negate_q7.c    
  *    
  * Description:	Negates Q7 vectors.    
  *    
  * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  *  
  * Redistribution and use in source and binary forms, with or without 
  * modification, are permitted provided that the following conditions
  * are met:
  *   - Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  *   - Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in
  *     the documentation and/or other materials provided with the 
  *     distribution.
  *   - Neither the name of ARM LIMITED nor the names of its contributors
  *     may be used to endorse or promote products derived from this
  *     software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.   
  * -------------------------------------------------------------------- */
  
  #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_FAMILY
  
  /* 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_FAMILY */
  
    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    
   */
  