00001 /* ---------------------------------------------------------------------- 00002 * Copyright (C) 2010 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 15. July 2011 00005 * $Revision: V1.0.10 00006 * 00007 * Project: CMSIS DSP Library 00008 * Title: arm_rms_f32.c 00009 * 00010 * Description: Root mean square value of an array of F32 type 00011 * 00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 00013 * 00014 * Version 1.0.10 2011/7/15 00015 * Big Endian support added and Merged M0 and M3/M4 Source code. 00016 * 00017 * Version 1.0.3 2010/11/29 00018 * Re-organized the CMSIS folders and updated documentation. 00019 * 00020 * Version 1.0.2 2010/11/11 00021 * Documentation updated. 00022 * 00023 * Version 1.0.1 2010/10/05 00024 * Production release and review comments incorporated. 00025 * 00026 * Version 1.0.0 2010/09/20 00027 * Production release and review comments incorporated. 00028 * ---------------------------------------------------------------------------- */ 00029 00030 #include "arm_math.h" 00031 00065 void arm_rms_f32( 00066 float32_t * pSrc, 00067 uint32_t blockSize, 00068 float32_t * pResult) 00069 { 00070 float32_t sum = 0.0f; /* Accumulator */ 00071 float32_t in; /* Tempoprary variable to store input value */ 00072 uint32_t blkCnt; /* loop counter */ 00073 00074 #ifndef ARM_MATH_CM0 00075 00076 /* Run the below code for Cortex-M4 and Cortex-M3 */ 00077 00078 /* loop Unrolling */ 00079 blkCnt = blockSize >> 2u; 00080 00081 /* First part of the processing with loop unrolling. Compute 4 outputs at a time. 00082 ** a second loop below computes the remaining 1 to 3 samples. */ 00083 while(blkCnt > 0u) 00084 { 00085 /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ 00086 /* Compute sum of the squares and then store the result in a temporary variable, sum */ 00087 in = *pSrc++; 00088 sum += in * in; 00089 in = *pSrc++; 00090 sum += in * in; 00091 in = *pSrc++; 00092 sum += in * in; 00093 in = *pSrc++; 00094 sum += in * in; 00095 00096 /* Decrement the loop counter */ 00097 blkCnt--; 00098 } 00099 00100 /* If the blockSize is not a multiple of 4, compute any remaining output samples here. 00101 ** No loop unrolling is used. */ 00102 blkCnt = blockSize % 0x4u; 00103 00104 #else 00105 00106 /* Run the below code for Cortex-M0 */ 00107 00108 /* Loop over blockSize number of values */ 00109 blkCnt = blockSize; 00110 00111 #endif /* #ifndef ARM_MATH_CM0 */ 00112 00113 while(blkCnt > 0u) 00114 { 00115 /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ 00116 /* Compute sum of the squares and then store the results in a temporary variable, sum */ 00117 in = *pSrc++; 00118 sum += in * in; 00119 00120 /* Decrement the loop counter */ 00121 blkCnt--; 00122 } 00123 00124 /* Compute Rms and store the result in the destination */ 00125 arm_sqrt_f32(sum / (float32_t) blockSize, pResult); 00126 } 00127