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  1. /* ----------------------------------------------------------------------    
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  3. *    
  4. * $Date:        19. March 2015
  5. * $Revision:    V.1.4.5
  6. *    
  7. * Project:          CMSIS DSP Library    
  8. * Title:                arm_negate_q7.c    
  9. *    
  10. * Description:  Negates Q7 vectors.    
  11. *    
  12. * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13. *  
  14. * Redistribution and use in source and binary forms, with or without
  15. * modification, are permitted provided that the following conditions
  16. * are met:
  17. *   - Redistributions of source code must retain the above copyright
  18. *     notice, this list of conditions and the following disclaimer.
  19. *   - Redistributions in binary form must reproduce the above copyright
  20. *     notice, this list of conditions and the following disclaimer in
  21. *     the documentation and/or other materials provided with the
  22. *     distribution.
  23. *   - Neither the name of ARM LIMITED nor the names of its contributors
  24. *     may be used to endorse or promote products derived from this
  25. *     software without specific prior written permission.
  26. *
  27. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30. * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31. * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32. * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33. * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35. * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37. * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38. * POSSIBILITY OF SUCH DAMAGE.  
  39. * -------------------------------------------------------------------- */
  40.  
  41. #include "arm_math.h"
  42.  
  43. /**    
  44.  * @ingroup groupMath    
  45.  */
  46.  
  47. /**    
  48.  * @addtogroup negate    
  49.  * @{    
  50.  */
  51.  
  52. /**    
  53.  * @brief  Negates the elements of a Q7 vector.    
  54.  * @param[in]  *pSrc points to the input vector    
  55.  * @param[out]  *pDst points to the output vector    
  56.  * @param[in]  blockSize number of samples in the vector    
  57.  * @return none.    
  58.  *    
  59.  * <b>Scaling and Overflow Behavior:</b>    
  60.  * \par    
  61.  * The function uses saturating arithmetic.    
  62.  * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.    
  63.  */
  64.  
  65. void arm_negate_q7(
  66.   q7_t * pSrc,
  67.   q7_t * pDst,
  68.   uint32_t blockSize)
  69. {
  70.   uint32_t blkCnt;                               /* loop counter */
  71.   q7_t in;
  72.  
  73. #ifndef ARM_MATH_CM0_FAMILY
  74.  
  75. /* Run the below code for Cortex-M4 and Cortex-M3 */
  76.   q31_t input;                                   /* Input values1-4 */
  77.   q31_t zero = 0x00000000;
  78.  
  79.  
  80.   /*loop Unrolling */
  81.   blkCnt = blockSize >> 2u;
  82.  
  83.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  84.    ** a second loop below computes the remaining 1 to 3 samples. */
  85.   while(blkCnt > 0u)
  86.   {
  87.     /* C = -A */
  88.     /* Read four inputs */
  89.     input = *__SIMD32(pSrc)++;
  90.  
  91.     /* Store the Negated results in the destination buffer in a single cycle by packing the results */
  92.     *__SIMD32(pDst)++ = __QSUB8(zero, input);
  93.  
  94.     /* Decrement the loop counter */
  95.     blkCnt--;
  96.   }
  97.  
  98.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  99.    ** No loop unrolling is used. */
  100.   blkCnt = blockSize % 0x4u;
  101.  
  102. #else
  103.  
  104.   /* Run the below code for Cortex-M0 */
  105.  
  106.   /* Initialize blkCnt with number of samples */
  107.   blkCnt = blockSize;
  108.  
  109. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  110.  
  111.   while(blkCnt > 0u)
  112.   {
  113.     /* C = -A */
  114.     /* Negate and then store the results in the destination buffer. */ \
  115.       in = *pSrc++;
  116.     *pDst++ = (in == (q7_t) 0x80) ? 0x7f : -in;
  117.  
  118.     /* Decrement the loop counter */
  119.     blkCnt--;
  120.   }
  121. }
  122.  
  123. /**    
  124.  * @} end of negate group    
  125.  */
  126.