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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_abs_q31.c    
  9. *    
  10. * Description:  Q31 vector absolute value.    
  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 BasicAbs    
  49.  * @{    
  50.  */
  51.  
  52.  
  53. /**    
  54.  * @brief Q31 vector absolute value.    
  55.  * @param[in]       *pSrc points to the input buffer    
  56.  * @param[out]      *pDst points to the output buffer    
  57.  * @param[in]       blockSize number of samples in each vector    
  58.  * @return none.    
  59.  *    
  60.  * <b>Scaling and Overflow Behavior:</b>    
  61.  * \par    
  62.  * The function uses saturating arithmetic.    
  63.  * The Q31 value -1 (0x80000000) will be saturated to the maximum allowable positive value 0x7FFFFFFF.    
  64.  */
  65.  
  66. void arm_abs_q31(
  67.   q31_t * pSrc,
  68.   q31_t * pDst,
  69.   uint32_t blockSize)
  70. {
  71.   uint32_t blkCnt;                               /* loop counter */
  72.   q31_t in;                                      /* Input value */
  73.  
  74. #ifndef ARM_MATH_CM0_FAMILY
  75.  
  76.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  77.   q31_t in1, in2, in3, in4;
  78.  
  79.   /*loop Unrolling */
  80.   blkCnt = blockSize >> 2u;
  81.  
  82.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  83.    ** a second loop below computes the remaining 1 to 3 samples. */
  84.   while(blkCnt > 0u)
  85.   {
  86.     /* C = |A| */
  87.     /* Calculate absolute of input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
  88.     in1 = *pSrc++;
  89.     in2 = *pSrc++;
  90.     in3 = *pSrc++;
  91.     in4 = *pSrc++;
  92.  
  93.     *pDst++ = (in1 > 0) ? in1 : (q31_t)__QSUB(0, in1);
  94.     *pDst++ = (in2 > 0) ? in2 : (q31_t)__QSUB(0, in2);
  95.     *pDst++ = (in3 > 0) ? in3 : (q31_t)__QSUB(0, in3);
  96.     *pDst++ = (in4 > 0) ? in4 : (q31_t)__QSUB(0, in4);
  97.  
  98.     /* Decrement the loop counter */
  99.     blkCnt--;
  100.   }
  101.  
  102.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  103.    ** No loop unrolling is used. */
  104.   blkCnt = blockSize % 0x4u;
  105.  
  106. #else
  107.  
  108.   /* Run the below code for Cortex-M0 */
  109.  
  110.   /* Initialize blkCnt with number of samples */
  111.   blkCnt = blockSize;
  112.  
  113. #endif /*   #ifndef ARM_MATH_CM0_FAMILY   */
  114.  
  115.   while(blkCnt > 0u)
  116.   {
  117.     /* C = |A| */
  118.     /* Calculate absolute value of the input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
  119.     in = *pSrc++;
  120.     *pDst++ = (in > 0) ? in : ((in == INT32_MIN) ? INT32_MAX : -in);
  121.  
  122.     /* Decrement the loop counter */
  123.     blkCnt--;
  124.   }
  125.  
  126. }
  127.  
  128. /**    
  129.  * @} end of BasicAbs group    
  130.  */
  131.