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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_f32.c    
  9. *    
  10. * Description:  Maximum value of a floating-point 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.  * @defgroup Max Maximum    
  49.  *    
  50.  * Computes the maximum value of an array of data.    
  51.  * The function returns both the maximum value and its position within the array.    
  52.  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.    
  53.  */
  54.  
  55. /**    
  56.  * @addtogroup Max    
  57.  * @{    
  58.  */
  59.  
  60.  
  61. /**    
  62.  * @brief Maximum value of a floating-point vector.    
  63.  * @param[in]       *pSrc points to the input vector    
  64.  * @param[in]       blockSize length of the input vector    
  65.  * @param[out]      *pResult maximum value returned here    
  66.  * @param[out]      *pIndex index of maximum value returned here    
  67.  * @return none.    
  68.  */
  69.  
  70. void arm_max_f32(
  71.   float32_t * pSrc,
  72.   uint32_t blockSize,
  73.   float32_t * pResult,
  74.   uint32_t * pIndex)
  75. {
  76. #ifndef ARM_MATH_CM0_FAMILY
  77.  
  78.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  79.   float32_t maxVal1, maxVal2, out;               /* Temporary variables to store the output value. */
  80.   uint32_t blkCnt, outIndex, count;              /* loop counter */
  81.  
  82.   /* Initialise the count value. */
  83.   count = 0u;
  84.   /* Initialise the index value to zero. */
  85.   outIndex = 0u;
  86.   /* Load first input value that act as reference value for comparision */
  87.   out = *pSrc++;
  88.  
  89.   /* Loop unrolling */
  90.   blkCnt = (blockSize - 1u) >> 2u;
  91.  
  92.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  93.   while(blkCnt > 0u)
  94.   {
  95.     /* Initialize maxVal to the next consecutive values one by one */
  96.     maxVal1 = *pSrc++;
  97.  
  98.     maxVal2 = *pSrc++;
  99.  
  100.     /* compare for the maximum value */
  101.     if(out < maxVal1)
  102.     {
  103.       /* Update the maximum value and its index */
  104.       out = maxVal1;
  105.       outIndex = count + 1u;
  106.     }
  107.  
  108.     maxVal1 = *pSrc++;
  109.  
  110.     /* compare for the maximum value */
  111.     if(out < maxVal2)
  112.     {
  113.       /* Update the maximum value and its index */
  114.       out = maxVal2;
  115.       outIndex = count + 2u;
  116.     }
  117.  
  118.     maxVal2 = *pSrc++;
  119.  
  120.     /* compare for the maximum value */
  121.     if(out < maxVal1)
  122.     {
  123.       /* Update the maximum value and its index */
  124.       out = maxVal1;
  125.       outIndex = count + 3u;
  126.     }
  127.  
  128.     /* compare for the maximum value */
  129.     if(out < maxVal2)
  130.     {
  131.       /* Update the maximum value and its index */
  132.       out = maxVal2;
  133.       outIndex = count + 4u;
  134.     }
  135.  
  136.     count += 4u;
  137.  
  138.     /* Decrement the loop counter */
  139.     blkCnt--;
  140.   }
  141.  
  142.   /* if (blockSize - 1u) is not multiple of 4 */
  143.   blkCnt = (blockSize - 1u) % 4u;
  144.  
  145. #else
  146.  
  147.   /* Run the below code for Cortex-M0 */
  148.   float32_t maxVal1, out;                        /* Temporary variables to store the output value. */
  149.   uint32_t blkCnt, outIndex;                     /* loop counter */
  150.  
  151.   /* Initialise the index value to zero. */
  152.   outIndex = 0u;
  153.   /* Load first input value that act as reference value for comparision */
  154.   out = *pSrc++;
  155.  
  156.   blkCnt = (blockSize - 1u);
  157.  
  158. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  159.  
  160.   while(blkCnt > 0u)
  161.   {
  162.     /* Initialize maxVal to the next consecutive values one by one */
  163.     maxVal1 = *pSrc++;
  164.  
  165.     /* compare for the maximum value */
  166.     if(out < maxVal1)
  167.     {
  168.       /* Update the maximum value and it's index */
  169.       out = maxVal1;
  170.       outIndex = blockSize - blkCnt;
  171.     }
  172.  
  173.  
  174.     /* Decrement the loop counter */
  175.     blkCnt--;
  176.  
  177.   }
  178.  
  179.   /* Store the maximum value and it's index into destination pointers */
  180.   *pResult = out;
  181.   *pIndex = outIndex;
  182. }
  183.  
  184. /**    
  185.  * @} end of Max group    
  186.  */
  187.