arm_max_q15.c

00001 /* ----------------------------------------------------------------------  
00002 * Copyright (C) 2010 ARM Limited. All rights reserved.  
00003 *  
00004 * $Date:        29. November 2010  
00005 * $Revision:    V1.0.3  
00006 *  
00007 * Project:      CMSIS DSP Library  
00008 * Title:        arm_max_q15.c  
00009 *  
00010 * Description:  Maximum value of a Q15 vector.  
00011 *  
00012 * Target Processor: Cortex-M4/Cortex-M3
00013 *  
00014 * Version 1.0.3 2010/11/29 
00015 *    Re-organized the CMSIS folders and updated documentation.  
00016 *   
00017 * Version 1.0.2 2010/11/11  
00018 *    Documentation updated.   
00019 *  
00020 * Version 1.0.1 2010/10/05   
00021 *    Production release and review comments incorporated.  
00022 *  
00023 * Version 1.0.0 2010/09/20   
00024 *    Production release and review comments incorporated.  
00025 * ---------------------------------------------------------------------------- */ 
00026  
00027 #include "arm_math.h" 
00028  
00029 /**  
00030  * @ingroup groupStats  
00031  */ 
00032  
00033 /**  
00034  * @addtogroup Max  
00035  * @{  
00036  */ 
00037  
00038  
00039 /**  
00040  * @brief Maximum value of a Q15 vector.  
00041  * @param[in]       *pSrc points to the input vector  
00042  * @param[in]       blockSize length of the input vector  
00043  * @param[out]      *pResult maximum value returned here  
00044  * @param[out]      *pIndex index of maximum value returned here  
00045  * @return none.  
00046  */ 
00047  
00048 void arm_max_q15( 
00049   q15_t * pSrc, 
00050   uint32_t blockSize, 
00051   q15_t * pResult, 
00052   uint32_t * pIndex) 
00053 { 
00054   q15_t maxVal, out;                             /* Temporary variables to store the output value. */ 
00055   uint32_t blkCnt, outIndex;                     /* loop counter */ 
00056  
00057   /* Initialise the index value to zero. */ 
00058   outIndex = 0u; 
00059   /* Load first input value that act as reference value for comparision */ 
00060   out = *pSrc++; 
00061  
00062   /* Loop over blockSize number of values */ 
00063   blkCnt = (blockSize - 1u); 
00064  
00065   do 
00066   { 
00067     /* Initialize maxVal to the next consecutive values one by one */ 
00068     maxVal = *pSrc++; 
00069  
00070     /* compare for the maximum value */ 
00071     if(out < maxVal) 
00072     { 
00073       /* Update the maximum value and its index */ 
00074       out = maxVal; 
00075       outIndex = blockSize - blkCnt; 
00076     } 
00077  
00078     blkCnt--; 
00079  
00080   } while(blkCnt > 0u); 
00081  
00082   /* Store the maximum value and its index into destination pointers */ 
00083   *pResult = out; 
00084   *pIndex = outIndex; 
00085 } 
00086  
00087 /**  
00088  * @} end of Max group  
00089  */