CMSIS DSP Software Library: arm_rms_q15.c Source File Main Page Modules Data Structures Files Examples File List Globals arm_rms_q15.c Go to the documentation of this file.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_rms_q15.c 00009 * 00010 * Description: Processing function for the Q15 RMS 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 00056 void arm_rms_q15( 00057 q15_t * pSrc, 00058 uint32_t blockSize, 00059 q15_t * pResult) 00060 { 00061 q63_t sum = 0; /* accumulator */ 00062 q31_t in; /* temporary variable to store the input value */ 00063 q15_t in1; /* temporary variable to store the input value */ 00064 uint32_t blkCnt; /* loop counter */ 00065 00066 /* loop Unrolling */ 00067 blkCnt = blockSize >> 2u; 00068 00069 /* First part of the processing with loop unrolling. Compute 4 outputs at a time. 00070 ** a second loop below computes the remaining 1 to 3 samples. */ 00071 while(blkCnt > 0u) 00072 { 00073 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */ 00074 /* Compute sum of the squares and then store the results in a temporary variable, sum */ 00075 in = *__SIMD32(pSrc)++; 00076 sum = __SMLALD(in, in, sum); 00077 in = *__SIMD32(pSrc)++; 00078 sum = __SMLALD(in, in, sum); 00079 00080 /* Decrement the loop counter */ 00081 blkCnt--; 00082 } 00083 00084 /* If the blockSize is not a multiple of 4, compute any remaining output samples here. 00085 ** No loop unrolling is used. */ 00086 blkCnt = blockSize % 0x4u; 00087 00088 while(blkCnt > 0u) 00089 { 00090 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */ 00091 /* Compute sum of the squares and then store the results in a temporary variable, sum */ 00092 in1 = *pSrc++; 00093 sum = __SMLALD(in1, in1, sum); 00094 00095 /* Decrement the loop counter */ 00096 blkCnt--; 00097 } 00098 00099 /* Truncating and saturating the accumulator to 1.15 format */ 00100 sum = __SSAT((q31_t) (sum >> 15), 16); 00101 00102 in1 = (q15_t) (sum / blockSize); 00103 00104 /* Store the result in the destination */ 00105 arm_sqrt_q15(in1, pResult); 00106 } 00107  All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Defines Generated on Mon Nov 29 2010 17:19:57 for CMSIS DSP Software Library by  1.7.2

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