arm_mean_f32.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_mean_f32.c
00004  * Description:  Mean value of a floating-point vector
00005  *
00006  * $Date:        27. January 2017
00007  * $Revision:    V.1.5.1
00008  *
00009  * Target Processor: Cortex-M cores
00010  * -------------------------------------------------------------------- */
00011 /*
00012  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
00013  *
00014  * SPDX-License-Identifier: Apache-2.0
00015  *
00016  * Licensed under the Apache License, Version 2.0 (the License); you may
00017  * not use this file except in compliance with the License.
00018  * You may obtain a copy of the License at
00019  *
00020  * www.apache.org/licenses/LICENSE-2.0
00021  *
00022  * Unless required by applicable law or agreed to in writing, software
00023  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
00024  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00025  * See the License for the specific language governing permissions and
00026  * limitations under the License.
00027  */
00028 
00029 #include "arm_math.h"
00030 
00031 /**
00032  * @ingroup groupStats
00033  */
00034 
00035 /**
00036  * @defgroup mean Mean
00037  *
00038  * Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector.
00039  * The underlying algorithm is used:
00040  *
00041  * <pre>
00042  *  Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;
00043  * </pre>
00044  *
00045  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
00046  */
00047 
00048 /**
00049  * @addtogroup mean
00050  * @{
00051  */
00052 
00053 
00054 /**
00055  * @brief Mean value of a floating-point vector.
00056  * @param[in]       *pSrc points to the input vector
00057  * @param[in]       blockSize length of the input vector
00058  * @param[out]      *pResult mean value returned here
00059  * @return none.
00060  */
00061 
00062 void arm_mean_f32(
00063   float32_t * pSrc,
00064   uint32_t blockSize,
00065   float32_t * pResult)
00066 {
00067   float32_t sum = 0.0f;                          /* Temporary result storage */
00068   uint32_t blkCnt;                               /* loop counter */
00069 
00070 #if defined (ARM_MATH_DSP)
00071   /* Run the below code for Cortex-M4 and Cortex-M3 */
00072 
00073   float32_t in1, in2, in3, in4;
00074 
00075   /*loop Unrolling */
00076   blkCnt = blockSize >> 2U;
00077 
00078   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
00079    ** a second loop below computes the remaining 1 to 3 samples. */
00080   while (blkCnt > 0U)
00081   {
00082     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
00083     in1 = *pSrc++;
00084     in2 = *pSrc++;
00085     in3 = *pSrc++;
00086     in4 = *pSrc++;
00087 
00088     sum += in1;
00089     sum += in2;
00090     sum += in3;
00091     sum += in4;
00092 
00093     /* Decrement the loop counter */
00094     blkCnt--;
00095   }
00096 
00097   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00098    ** No loop unrolling is used. */
00099   blkCnt = blockSize % 0x4U;
00100 
00101 #else
00102   /* Run the below code for Cortex-M0 */
00103 
00104   /* Loop over blockSize number of values */
00105   blkCnt = blockSize;
00106 
00107 #endif /* #if defined (ARM_MATH_DSP) */
00108 
00109   while (blkCnt > 0U)
00110   {
00111     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
00112     sum += *pSrc++;
00113 
00114     /* Decrement the loop counter */
00115     blkCnt--;
00116   }
00117 
00118   /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize  */
00119   /* Store the result to the destination */
00120   *pResult = sum / (float32_t) blockSize;
00121 }
00122 
00123 /**
00124  * @} end of mean group
00125  */
00126