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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_q7.c    
  9. *    
  10. * Description:  Q7 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.  * @brief Q7 vector absolute value.        
  54.  * @param[in]       *pSrc points to the input buffer        
  55.  * @param[out]      *pDst points to the output buffer        
  56.  * @param[in]       blockSize number of samples in each vector        
  57.  * @return none.        
  58.  *    
  59.  * \par Conditions for optimum performance    
  60.  *  Input and output buffers should be aligned by 32-bit    
  61.  *    
  62.  *        
  63.  * <b>Scaling and Overflow Behavior:</b>        
  64.  * \par        
  65.  * The function uses saturating arithmetic.        
  66.  * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.        
  67.  */
  68.  
  69. void arm_abs_q7(
  70.   q7_t * pSrc,
  71.   q7_t * pDst,
  72.   uint32_t blockSize)
  73. {
  74.   uint32_t blkCnt;                               /* loop counter */
  75.   q7_t in;                                       /* Input value1 */
  76.  
  77. #ifndef ARM_MATH_CM0_FAMILY
  78.  
  79.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  80.   q31_t in1, in2, in3, in4;                      /* temporary input variables */
  81.   q31_t out1, out2, out3, out4;                  /* temporary output variables */
  82.  
  83.   /*loop Unrolling */
  84.   blkCnt = blockSize >> 2u;
  85.  
  86.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  87.    ** a second loop below computes the remaining 1 to 3 samples. */
  88.   while(blkCnt > 0u)
  89.   {
  90.     /* C = |A| */
  91.     /* Read inputs */
  92.     in1 = (q31_t) * pSrc;
  93.     in2 = (q31_t) * (pSrc + 1);
  94.     in3 = (q31_t) * (pSrc + 2);
  95.  
  96.     /* find absolute value */
  97.     out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
  98.  
  99.     /* read input */
  100.     in4 = (q31_t) * (pSrc + 3);
  101.  
  102.     /* find absolute value */
  103.     out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
  104.  
  105.     /* store result to destination */
  106.     *pDst = (q7_t) out1;
  107.  
  108.     /* find absolute value */
  109.     out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
  110.  
  111.     /* find absolute value */
  112.     out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
  113.  
  114.     /* store result to destination */
  115.     *(pDst + 1) = (q7_t) out2;
  116.  
  117.     /* store result to destination */
  118.     *(pDst + 2) = (q7_t) out3;
  119.  
  120.     /* store result to destination */
  121.     *(pDst + 3) = (q7_t) out4;
  122.  
  123.     /* update pointers to process next samples */
  124.     pSrc += 4u;
  125.     pDst += 4u;
  126.  
  127.     /* Decrement the loop counter */
  128.     blkCnt--;
  129.   }
  130.  
  131.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  132.    ** No loop unrolling is used. */
  133.   blkCnt = blockSize % 0x4u;
  134. #else
  135.  
  136.   /* Run the below code for Cortex-M0 */
  137.   blkCnt = blockSize;
  138.  
  139. #endif /* #define ARM_MATH_CM0_FAMILY */
  140.  
  141.   while(blkCnt > 0u)
  142.   {
  143.     /* C = |A| */
  144.     /* Read the input */
  145.     in = *pSrc++;
  146.  
  147.     /* Store the Absolute result in the destination buffer */
  148.     *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
  149.  
  150.     /* Decrement the loop counter */
  151.     blkCnt--;
  152.   }
  153. }
  154.  
  155. /**        
  156.  * @} end of BasicAbs group        
  157.  */
  158.