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# arm_rms_f32.c

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    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

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