arm_mean_f32.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_mean_f32.c  
00009 *  
00010 * Description:  Mean value of two floating point arrays.  
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  * @defgroup mean Mean  
00035  *  
00036  * Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector.  
00037  * The underlying algorithm is used:  
00038  *  
00039  * <pre>  
00040  *  Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;  
00041  * </pre>  
00042  *  
00043  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.  
00044  */ 
00045  
00046 /**  
00047  * @addtogroup mean  
00048  * @{  
00049  */ 
00050  
00051  
00052 /**  
00053  * @brief Mean value of a floating-point vector.  
00054  * @param[in]       *pSrc points to the input vector  
00055  * @param[in]       blockSize length of the input vector  
00056  * @param[out]      *pResult mean value returned here  
00057  * @return none.  
00058  */ 
00059  
00060  
00061 void arm_mean_f32( 
00062   float32_t * pSrc, 
00063   uint32_t blockSize, 
00064   float32_t * pResult) 
00065 { 
00066   float32_t sum = 0.0f;                          /* Temporary result storage */ 
00067   uint32_t blkCnt;                               /* loop counter */ 
00068  
00069   /*loop Unrolling */ 
00070   blkCnt = blockSize >> 2u; 
00071  
00072   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00073    ** a second loop below computes the remaining 1 to 3 samples. */ 
00074   while(blkCnt > 0u) 
00075   { 
00076     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ 
00077     sum += *pSrc++; 
00078     sum += *pSrc++; 
00079     sum += *pSrc++; 
00080     sum += *pSrc++; 
00081  
00082     /* Decrement the loop counter */ 
00083     blkCnt--; 
00084   } 
00085  
00086   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.  
00087    ** No loop unrolling is used. */ 
00088   blkCnt = blockSize % 0x4u; 
00089  
00090   while(blkCnt > 0u) 
00091   { 
00092     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ 
00093     sum += *pSrc++; 
00094  
00095     /* Decrement the loop counter */ 
00096     blkCnt--; 
00097   } 
00098  
00099   /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize  */ 
00100   /* Store the result to the destination */ 
00101   *pResult = sum / (float32_t) blockSize; 
00102 } 
00103  
00104 /**  
00105  * @} end of mean group  
00106  */