Laxmi Kant Tiwari / mbed-dsp

CMSIS DSP Lib

Fork of mbed-dsp by mbed official

cmsis_dsp/StatisticsFunctions/arm_mean_q15.c@4:9cee975aadce, 2014-06-23 (annotated)

Committer:
mbed_official
Date:
Mon Jun 23 09:30:09 2014 +0100
Revision:
4:9cee975aadce
Parent:
3:7a284390b0ce 
Synchronized with git revision 6e7c7bcec41226f536474daae3c13d49e4c0e865



Full URL: https://github.com/mbedmicro/mbed/commit/6e7c7bcec41226f536474daae3c13d49e4c0e865/



Fix signed unsigned compare in dsp library

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_q15.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Mean value of a Q15 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 Q15 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 32-bit internal accumulator.
emilmont 1:fdd22bb7aa52 63 * The input is represented in 1.15 format and is accumulated in a 32-bit
emilmont 1:fdd22bb7aa52 64 * accumulator in 17.15 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 saturated and truncated to yield a result of 1.15 format.
emilmont 1:fdd22bb7aa52 68 *
emilmont 1:fdd22bb7aa52 69 */
emilmont 1:fdd22bb7aa52 70
emilmont 1:fdd22bb7aa52 71
emilmont 1:fdd22bb7aa52 72 void arm_mean_q15(
emilmont 1:fdd22bb7aa52 73 q15_t * pSrc,
emilmont 1:fdd22bb7aa52 74 uint32_t blockSize,
emilmont 1:fdd22bb7aa52 75 q15_t * pResult)
emilmont 1:fdd22bb7aa52 76 {
emilmont 1:fdd22bb7aa52 77 q31_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 in;
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 in = *__SIMD32(pSrc)++;
emilmont 1:fdd22bb7aa52 94 sum += ((in << 16) >> 16);
emilmont 1:fdd22bb7aa52 95 sum += (in >> 16);
emilmont 1:fdd22bb7aa52 96 in = *__SIMD32(pSrc)++;
emilmont 1:fdd22bb7aa52 97 sum += ((in << 16) >> 16);
emilmont 1:fdd22bb7aa52 98 sum += (in >> 16);
emilmont 1:fdd22bb7aa52 99
emilmont 1:fdd22bb7aa52 100 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 101 blkCnt--;
emilmont 1:fdd22bb7aa52 102 }
emilmont 1:fdd22bb7aa52 103
emilmont 1:fdd22bb7aa52 104 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 105 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 106 blkCnt = blockSize % 0x4u;
emilmont 1:fdd22bb7aa52 107
emilmont 1:fdd22bb7aa52 108 #else
emilmont 1:fdd22bb7aa52 109
emilmont 1:fdd22bb7aa52 110 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 111
emilmont 1:fdd22bb7aa52 112 /* Loop over blockSize number of values */
emilmont 1:fdd22bb7aa52 113 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 114
mbed_official 3:7a284390b0ce 115 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
emilmont 1:fdd22bb7aa52 116
emilmont 1:fdd22bb7aa52 117 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 118 {
emilmont 1:fdd22bb7aa52 119 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 120 sum += *pSrc++;
emilmont 1:fdd22bb7aa52 121
emilmont 1:fdd22bb7aa52 122 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 123 blkCnt--;
emilmont 1:fdd22bb7aa52 124 }
emilmont 1:fdd22bb7aa52 125
emilmont 1:fdd22bb7aa52 126 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */
emilmont 1:fdd22bb7aa52 127 /* Store the result to the destination */
emilmont 1:fdd22bb7aa52 128 *pResult = (q15_t) (sum / blockSize);
emilmont 1:fdd22bb7aa52 129 }
emilmont 1:fdd22bb7aa52 130
emilmont 1:fdd22bb7aa52 131 /**
emilmont 1:fdd22bb7aa52 132 * @} end of mean group
emilmont 1:fdd22bb7aa52 133 */