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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_q15.c    
  9. *    
  10. * Description:  Q15 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 Q15 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.  * <b>Scaling and Overflow Behavior:</b>    
  60.  * \par    
  61.  * The function uses saturating arithmetic.    
  62.  * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.    
  63.  */
  64.  
  65. void arm_abs_q15(
  66.   q15_t * pSrc,
  67.   q15_t * pDst,
  68.   uint32_t blockSize)
  69. {
  70.   uint32_t blkCnt;                               /* loop counter */
  71.  
  72. #ifndef ARM_MATH_CM0_FAMILY
  73.   __SIMD32_TYPE *simd;
  74.  
  75. /* Run the below code for Cortex-M4 and Cortex-M3 */
  76.  
  77.   q15_t in1;                                     /* Input value1 */
  78.   q15_t in2;                                     /* Input value2 */
  79.  
  80.  
  81.   /*loop Unrolling */
  82.   blkCnt = blockSize >> 2u;
  83.  
  84.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  85.    ** a second loop below computes the remaining 1 to 3 samples. */
  86.   simd = __SIMD32_CONST(pDst);
  87.   while(blkCnt > 0u)
  88.   {
  89.     /* C = |A| */
  90.     /* Read two inputs */
  91.     in1 = *pSrc++;
  92.     in2 = *pSrc++;
  93.  
  94.  
  95.     /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
  96. #ifndef  ARM_MATH_BIG_ENDIAN
  97.     *simd++ =
  98.       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
  99.               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
  100.  
  101. #else
  102.  
  103.  
  104.     *simd++ =
  105.       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
  106.               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
  107.  
  108. #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
  109.  
  110.     in1 = *pSrc++;
  111.     in2 = *pSrc++;
  112.  
  113.  
  114. #ifndef  ARM_MATH_BIG_ENDIAN
  115.  
  116.     *simd++ =
  117.       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
  118.               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
  119.  
  120. #else
  121.  
  122.  
  123.     *simd++ =
  124.       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
  125.               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
  126.  
  127. #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
  128.  
  129.     /* Decrement the loop counter */
  130.     blkCnt--;
  131.   }
  132.   pDst = (q15_t *)simd;
  133.        
  134.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  135.    ** No loop unrolling is used. */
  136.   blkCnt = blockSize % 0x4u;
  137.  
  138.   while(blkCnt > 0u)
  139.   {
  140.     /* C = |A| */
  141.     /* Read the input */
  142.     in1 = *pSrc++;
  143.  
  144.     /* Calculate absolute value of input and then store the result in the destination buffer. */
  145.     *pDst++ = (in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1);
  146.  
  147.     /* Decrement the loop counter */
  148.     blkCnt--;
  149.   }
  150.  
  151. #else
  152.  
  153.   /* Run the below code for Cortex-M0 */
  154.  
  155.   q15_t in;                                      /* Temporary input variable */
  156.  
  157.   /* Initialize blkCnt with number of samples */
  158.   blkCnt = blockSize;
  159.  
  160.   while(blkCnt > 0u)
  161.   {
  162.     /* C = |A| */
  163.     /* Read the input */
  164.     in = *pSrc++;
  165.  
  166.     /* Calculate absolute value of input and then store the result in the destination buffer. */
  167.     *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
  168.  
  169.     /* Decrement the loop counter */
  170.     blkCnt--;
  171.   }
  172.  
  173. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  174.  
  175. }
  176.  
  177. /**    
  178.  * @} end of BasicAbs group    
  179.  */
  180.