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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_max_q31.c    
  9. *    
  10. * Description:  Maximum value of a Q31 vector.    
  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 groupStats    
  45.  */
  46.  
  47. /**    
  48.  * @addtogroup Max    
  49.  * @{    
  50.  */
  51.  
  52.  
  53. /**    
  54.  * @brief Maximum value of a Q31 vector.    
  55.  * @param[in]       *pSrc points to the input vector    
  56.  * @param[in]       blockSize length of the input vector    
  57.  * @param[out]      *pResult maximum value returned here    
  58.  * @param[out]      *pIndex index of maximum value returned here    
  59.  * @return none.    
  60.  */
  61.  
  62. void arm_max_q31(
  63.   q31_t * pSrc,
  64.   uint32_t blockSize,
  65.   q31_t * pResult,
  66.   uint32_t * pIndex)
  67. {
  68. #ifndef ARM_MATH_CM0_FAMILY
  69.  
  70.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  71.   q31_t maxVal1, maxVal2, out;                   /* Temporary variables to store the output value. */
  72.   uint32_t blkCnt, outIndex, count;              /* loop counter */
  73.  
  74.   /* Initialise the count value. */
  75.   count = 0u;
  76.   /* Initialise the index value to zero. */
  77.   outIndex = 0u;
  78.   /* Load first input value that act as reference value for comparision */
  79.   out = *pSrc++;
  80.  
  81.   /* Loop unrolling */
  82.   blkCnt = (blockSize - 1u) >> 2u;
  83.  
  84.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  85.   while(blkCnt > 0u)
  86.   {
  87.     /* Initialize maxVal to the next consecutive values one by one */
  88.     maxVal1 = *pSrc++;
  89.  
  90.     maxVal2 = *pSrc++;
  91.  
  92.     /* compare for the maximum value */
  93.     if(out < maxVal1)
  94.     {
  95.       /* Update the maximum value and its index */
  96.       out = maxVal1;
  97.       outIndex = count + 1u;
  98.     }
  99.  
  100.     maxVal1 = *pSrc++;
  101.  
  102.     /* compare for the maximum value */
  103.     if(out < maxVal2)
  104.     {
  105.       /* Update the maximum value and its index */
  106.       out = maxVal2;
  107.       outIndex = count + 2u;
  108.     }
  109.  
  110.     maxVal2 = *pSrc++;
  111.  
  112.     /* compare for the maximum value */
  113.     if(out < maxVal1)
  114.     {
  115.       /* Update the maximum value and its index */
  116.       out = maxVal1;
  117.       outIndex = count + 3u;
  118.     }
  119.  
  120.     /* compare for the maximum value */
  121.     if(out < maxVal2)
  122.     {
  123.       /* Update the maximum value and its index */
  124.       out = maxVal2;
  125.       outIndex = count + 4u;
  126.     }
  127.  
  128.     count += 4u;
  129.  
  130.     /* Decrement the loop counter */
  131.     blkCnt--;
  132.   }
  133.  
  134.   /* if (blockSize - 1u) is not multiple of 4 */
  135.   blkCnt = (blockSize - 1u) % 4u;
  136.  
  137. #else
  138.  
  139.   /* Run the below code for Cortex-M0 */
  140.   q31_t maxVal1, out;                            /* Temporary variables to store the output value. */
  141.   uint32_t blkCnt, outIndex;                     /* loop counter */
  142.  
  143.   /* Initialise the index value to zero. */
  144.   outIndex = 0u;
  145.   /* Load first input value that act as reference value for comparision */
  146.   out = *pSrc++;
  147.  
  148.   blkCnt = (blockSize - 1u);
  149.  
  150. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  151.  
  152.   while(blkCnt > 0u)
  153.   {
  154.     /* Initialize maxVal to the next consecutive values one by one */
  155.     maxVal1 = *pSrc++;
  156.  
  157.     /* compare for the maximum value */
  158.     if(out < maxVal1)
  159.     {
  160.       /* Update the maximum value and it's index */
  161.       out = maxVal1;
  162.       outIndex = blockSize - blkCnt;
  163.     }
  164.  
  165.     /* Decrement the loop counter */
  166.     blkCnt--;
  167.  
  168.   }
  169.  
  170.   /* Store the maximum value and its index into destination pointers */
  171.   *pResult = out;
  172.   *pIndex = outIndex;
  173. }
  174.  
  175. /**    
  176.  * @} end of Max group    
  177.  */
  178.