arm_mean_f32.c

00001 /* ----------------------------------------------------------------------    
00002 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        17. January 2013
00005 * $Revision:    V1.4.1  
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_mean_f32.c    
00009 *    
00010 * Description:  Mean value of a floating-point vector.   
00011 *    
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *  
00014 * Redistribution and use in source and binary forms, with or without 
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the 
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.    
00039 * ---------------------------------------------------------------------------- */
00040 
00041 #include "arm_math.h"
00042 
00043 /**    
00044  * @ingroup groupStats    
00045  */
00046 
00047 /**    
00048  * @defgroup mean Mean    
00049  *    
00050  * Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector.    
00051  * The underlying algorithm is used:    
00052  *    
00053  * <pre>    
00054  *  Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;    
00055  * </pre>    
00056  *    
00057  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.    
00058  */
00059 
00060 /**    
00061  * @addtogroup mean    
00062  * @{    
00063  */
00064 
00065 
00066 /**    
00067  * @brief Mean value of a floating-point vector.    
00068  * @param[in]       *pSrc points to the input vector    
00069  * @param[in]       blockSize length of the input vector    
00070  * @param[out]      *pResult mean value returned here    
00071  * @return none.    
00072  */
00073 
00074 
00075 void arm_mean_f32(
00076   float32_t * pSrc,
00077   uint32_t blockSize,
00078   float32_t * pResult)
00079 {
00080   float32_t sum = 0.0f;                          /* Temporary result storage */
00081   uint32_t blkCnt;                               /* loop counter */
00082 
00083 #ifndef ARM_MATH_CM0_FAMILY
00084 
00085   /* Run the below code for Cortex-M4 and Cortex-M3 */
00086   float32_t in1, in2, in3, in4;
00087 
00088   /*loop Unrolling */
00089   blkCnt = blockSize >> 2u;
00090 
00091   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
00092    ** a second loop below computes the remaining 1 to 3 samples. */
00093   while(blkCnt > 0u)
00094   {
00095     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
00096     in1 = *pSrc++;
00097     in2 = *pSrc++;
00098     in3 = *pSrc++;
00099     in4 = *pSrc++;
00100 
00101     sum += in1;
00102     sum += in2;
00103     sum += in3;
00104     sum += in4;
00105 
00106     /* Decrement the loop counter */
00107     blkCnt--;
00108   }
00109 
00110   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
00111    ** No loop unrolling is used. */
00112   blkCnt = blockSize % 0x4u;
00113 
00114 #else
00115 
00116   /* Run the below code for Cortex-M0 */
00117 
00118   /* Loop over blockSize number of values */
00119   blkCnt = blockSize;
00120 
00121 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
00122 
00123   while(blkCnt > 0u)
00124   {
00125     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
00126     sum += *pSrc++;
00127 
00128     /* Decrement the loop counter */
00129     blkCnt--;
00130   }
00131 
00132   /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize  */
00133   /* Store the result to the destination */
00134   *pResult = sum / (float32_t) blockSize;
00135 }
00136 
00137 /**    
00138  * @} end of mean group    
00139  */