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CMSIS DSP library

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cmsis_dsp/StatisticsFunctions/arm_mean_q31.c@3:7a284390b0ce, 2013-11-08 (annotated)

Committer:
mbed_official
Date:
Fri Nov 08 13:45:10 2013 +0000
Revision:
3:7a284390b0ce
Parent:
2:da51fb522205 
Synchronized with git revision e69956aba2f68a2a26ac26b051f8d349deaa1ce8

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
mbed_official 3:7a284390b0ce 2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
mbed_official 3:7a284390b0ce 4 * $Date: 17. January 2013
mbed_official 3:7a284390b0ce 5 * $Revision: V1.4.1
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_mean_q31.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Mean value of a Q31 vector.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
mbed_official 3:7a284390b0ce 14 * Redistribution and use in source and binary forms, with or without
mbed_official 3:7a284390b0ce 15 * modification, are permitted provided that the following conditions
mbed_official 3:7a284390b0ce 16 * are met:
mbed_official 3:7a284390b0ce 17 * - Redistributions of source code must retain the above copyright
mbed_official 3:7a284390b0ce 18 * notice, this list of conditions and the following disclaimer.
mbed_official 3:7a284390b0ce 19 * - Redistributions in binary form must reproduce the above copyright
mbed_official 3:7a284390b0ce 20 * notice, this list of conditions and the following disclaimer in
mbed_official 3:7a284390b0ce 21 * the documentation and/or other materials provided with the
mbed_official 3:7a284390b0ce 22 * distribution.
mbed_official 3:7a284390b0ce 23 * - Neither the name of ARM LIMITED nor the names of its contributors
mbed_official 3:7a284390b0ce 24 * may be used to endorse or promote products derived from this
mbed_official 3:7a284390b0ce 25 * software without specific prior written permission.
mbed_official 3:7a284390b0ce 26 *
mbed_official 3:7a284390b0ce 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
mbed_official 3:7a284390b0ce 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
mbed_official 3:7a284390b0ce 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
mbed_official 3:7a284390b0ce 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
mbed_official 3:7a284390b0ce 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
mbed_official 3:7a284390b0ce 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
mbed_official 3:7a284390b0ce 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
mbed_official 3:7a284390b0ce 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
mbed_official 3:7a284390b0ce 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
mbed_official 3:7a284390b0ce 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
mbed_official 3:7a284390b0ce 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
mbed_official 3:7a284390b0ce 38 * POSSIBILITY OF SUCH DAMAGE.
emilmont 1:fdd22bb7aa52 39 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 40
emilmont 1:fdd22bb7aa52 41 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 42
emilmont 1:fdd22bb7aa52 43 /**
emilmont 1:fdd22bb7aa52 44 * @ingroup groupStats
emilmont 1:fdd22bb7aa52 45 */
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47 /**
emilmont 1:fdd22bb7aa52 48 * @addtogroup mean
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52 /**
emilmont 1:fdd22bb7aa52 53 * @brief Mean value of a Q31 vector.
emilmont 1:fdd22bb7aa52 54 * @param[in] *pSrc points to the input vector
emilmont 1:fdd22bb7aa52 55 * @param[in] blockSize length of the input vector
emilmont 1:fdd22bb7aa52 56 * @param[out] *pResult mean value returned here
emilmont 1:fdd22bb7aa52 57 * @return none.
emilmont 1:fdd22bb7aa52 58 *
emilmont 1:fdd22bb7aa52 59 * @details
emilmont 1:fdd22bb7aa52 60 * <b>Scaling and Overflow Behavior:</b>
emilmont 1:fdd22bb7aa52 61 *\par
emilmont 1:fdd22bb7aa52 62 * The function is implemented using a 64-bit internal accumulator.
emilmont 1:fdd22bb7aa52 63 * The input is represented in 1.31 format and is accumulated in a 64-bit
emilmont 1:fdd22bb7aa52 64 * accumulator in 33.31 format.
emilmont 1:fdd22bb7aa52 65 * There is no risk of internal overflow with this approach, and the
emilmont 1:fdd22bb7aa52 66 * full precision of intermediate result is preserved.
emilmont 1:fdd22bb7aa52 67 * Finally, the accumulator is truncated to yield a result of 1.31 format.
emilmont 1:fdd22bb7aa52 68 *
emilmont 1:fdd22bb7aa52 69 */
emilmont 1:fdd22bb7aa52 70
emilmont 1:fdd22bb7aa52 71
emilmont 1:fdd22bb7aa52 72 void arm_mean_q31(
emilmont 1:fdd22bb7aa52 73 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 74 uint32_t blockSize,
emilmont 1:fdd22bb7aa52 75 q31_t * pResult)
emilmont 1:fdd22bb7aa52 76 {
emilmont 1:fdd22bb7aa52 77 q63_t sum = 0; /* Temporary result storage */
emilmont 1:fdd22bb7aa52 78 uint32_t blkCnt; /* loop counter */
emilmont 1:fdd22bb7aa52 79
mbed_official 3:7a284390b0ce 80 #ifndef ARM_MATH_CM0_FAMILY
emilmont 1:fdd22bb7aa52 81
emilmont 1:fdd22bb7aa52 82 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 83 q31_t in1, in2, in3, in4;
emilmont 1:fdd22bb7aa52 84
emilmont 1:fdd22bb7aa52 85 /*loop Unrolling */
emilmont 1:fdd22bb7aa52 86 blkCnt = blockSize >> 2u;
emilmont 1:fdd22bb7aa52 87
emilmont 1:fdd22bb7aa52 88 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emilmont 1:fdd22bb7aa52 89 ** a second loop below computes the remaining 1 to 3 samples. */
emilmont 1:fdd22bb7aa52 90 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 91 {
emilmont 1:fdd22bb7aa52 92 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 93 in1 = *pSrc++;
emilmont 1:fdd22bb7aa52 94 in2 = *pSrc++;
emilmont 1:fdd22bb7aa52 95 in3 = *pSrc++;
emilmont 1:fdd22bb7aa52 96 in4 = *pSrc++;
emilmont 1:fdd22bb7aa52 97
emilmont 1:fdd22bb7aa52 98 sum += in1;
emilmont 1:fdd22bb7aa52 99 sum += in2;
emilmont 1:fdd22bb7aa52 100 sum += in3;
emilmont 1:fdd22bb7aa52 101 sum += in4;
emilmont 1:fdd22bb7aa52 102
emilmont 1:fdd22bb7aa52 103 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 104 blkCnt--;
emilmont 1:fdd22bb7aa52 105 }
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 108 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 109 blkCnt = blockSize % 0x4u;
emilmont 1:fdd22bb7aa52 110
emilmont 1:fdd22bb7aa52 111 #else
emilmont 1:fdd22bb7aa52 112
emilmont 1:fdd22bb7aa52 113 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 114
emilmont 1:fdd22bb7aa52 115 /* Loop over blockSize number of values */
emilmont 1:fdd22bb7aa52 116 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 117
mbed_official 3:7a284390b0ce 118 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
emilmont 1:fdd22bb7aa52 119
emilmont 1:fdd22bb7aa52 120 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 121 {
emilmont 1:fdd22bb7aa52 122 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 123 sum += *pSrc++;
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 126 blkCnt--;
emilmont 1:fdd22bb7aa52 127 }
emilmont 1:fdd22bb7aa52 128
emilmont 1:fdd22bb7aa52 129 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */
emilmont 1:fdd22bb7aa52 130 /* Store the result to the destination */
emilmont 1:fdd22bb7aa52 131 *pResult = (q31_t) (sum / (int32_t) blockSize);
emilmont 1:fdd22bb7aa52 132 }
emilmont 1:fdd22bb7aa52 133
emilmont 1:fdd22bb7aa52 134 /**
emilmont 1:fdd22bb7aa52 135 * @} end of mean group
emilmont 1:fdd22bb7aa52 136 */