Eli Hughes / CMSIS_DSP_401

V4.0.1 of the ARM CMSIS DSP libraries. Note that arm_bitreversal2.s, arm_cfft_f32.c and arm_rfft_fast_f32.c had to be removed. arm_bitreversal2.s will not assemble with the online tools. So, the fast f32 FFT functions are not yet available. All the other FFT functions are available.

Dependents:   MPU9150_Example fir_f32 fir_f32 MPU9150_nucleo_noni2cdev ... more

StatisticsFunctions/arm_var_q31.c@0:3d9c67d97d6f, 2014-07-28 (annotated)

Committer:
emh203
Date:
Mon Jul 28 15:03:15 2014 +0000
Revision:
0:3d9c67d97d6f
1st working commit.   Had to remove arm_bitreversal2.s     arm_cfft_f32.c and arm_rfft_fast_f32.c.    The .s will not assemble.      For now I removed these functions so we could at least have a library for the other functions.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emh203 0:3d9c67d97d6f 1 /* ----------------------------------------------------------------------
emh203 0:3d9c67d97d6f 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emh203 0:3d9c67d97d6f 3 *
emh203 0:3d9c67d97d6f 4 * $Date: 12. March 2014
emh203 0:3d9c67d97d6f 5 * $Revision: V1.4.3
emh203 0:3d9c67d97d6f 6 *
emh203 0:3d9c67d97d6f 7 * Project: CMSIS DSP Library
emh203 0:3d9c67d97d6f 8 * Title: arm_var_q31.c
emh203 0:3d9c67d97d6f 9 *
emh203 0:3d9c67d97d6f 10 * Description: Variance of an array of Q31 type.
emh203 0:3d9c67d97d6f 11 *
emh203 0:3d9c67d97d6f 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emh203 0:3d9c67d97d6f 13 *
emh203 0:3d9c67d97d6f 14 * Redistribution and use in source and binary forms, with or without
emh203 0:3d9c67d97d6f 15 * modification, are permitted provided that the following conditions
emh203 0:3d9c67d97d6f 16 * are met:
emh203 0:3d9c67d97d6f 17 * - Redistributions of source code must retain the above copyright
emh203 0:3d9c67d97d6f 18 * notice, this list of conditions and the following disclaimer.
emh203 0:3d9c67d97d6f 19 * - Redistributions in binary form must reproduce the above copyright
emh203 0:3d9c67d97d6f 20 * notice, this list of conditions and the following disclaimer in
emh203 0:3d9c67d97d6f 21 * the documentation and/or other materials provided with the
emh203 0:3d9c67d97d6f 22 * distribution.
emh203 0:3d9c67d97d6f 23 * - Neither the name of ARM LIMITED nor the names of its contributors
emh203 0:3d9c67d97d6f 24 * may be used to endorse or promote products derived from this
emh203 0:3d9c67d97d6f 25 * software without specific prior written permission.
emh203 0:3d9c67d97d6f 26 *
emh203 0:3d9c67d97d6f 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
emh203 0:3d9c67d97d6f 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
emh203 0:3d9c67d97d6f 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
emh203 0:3d9c67d97d6f 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
emh203 0:3d9c67d97d6f 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
emh203 0:3d9c67d97d6f 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
emh203 0:3d9c67d97d6f 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
emh203 0:3d9c67d97d6f 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
emh203 0:3d9c67d97d6f 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
emh203 0:3d9c67d97d6f 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
emh203 0:3d9c67d97d6f 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
emh203 0:3d9c67d97d6f 38 * POSSIBILITY OF SUCH DAMAGE.
emh203 0:3d9c67d97d6f 39 * -------------------------------------------------------------------- */
emh203 0:3d9c67d97d6f 40
emh203 0:3d9c67d97d6f 41 #include "arm_math.h"
emh203 0:3d9c67d97d6f 42
emh203 0:3d9c67d97d6f 43 /**
emh203 0:3d9c67d97d6f 44 * @ingroup groupStats
emh203 0:3d9c67d97d6f 45 */
emh203 0:3d9c67d97d6f 46
emh203 0:3d9c67d97d6f 47 /**
emh203 0:3d9c67d97d6f 48 * @addtogroup variance
emh203 0:3d9c67d97d6f 49 * @{
emh203 0:3d9c67d97d6f 50 */
emh203 0:3d9c67d97d6f 51
emh203 0:3d9c67d97d6f 52 /**
emh203 0:3d9c67d97d6f 53 * @brief Variance of the elements of a Q31 vector.
emh203 0:3d9c67d97d6f 54 * @param[in] *pSrc points to the input vector
emh203 0:3d9c67d97d6f 55 * @param[in] blockSize length of the input vector
emh203 0:3d9c67d97d6f 56 * @param[out] *pResult variance value returned here
emh203 0:3d9c67d97d6f 57 * @return none.
emh203 0:3d9c67d97d6f 58 *
emh203 0:3d9c67d97d6f 59 * @details
emh203 0:3d9c67d97d6f 60 * <b>Scaling and Overflow Behavior:</b>
emh203 0:3d9c67d97d6f 61 *
emh203 0:3d9c67d97d6f 62 *\par
emh203 0:3d9c67d97d6f 63 * The function is implemented using an internal 64-bit accumulator.
emh203 0:3d9c67d97d6f 64 * The input is represented in 1.31 format, which is then downshifted by 8 bits
emh203 0:3d9c67d97d6f 65 * which yields 1.23, and intermediate multiplication yields a 2.46 format.
emh203 0:3d9c67d97d6f 66 * The accumulator maintains full precision of the intermediate multiplication results,
emh203 0:3d9c67d97d6f 67 * but provides only a 16 guard bits.
emh203 0:3d9c67d97d6f 68 * There is no saturation on intermediate additions.
emh203 0:3d9c67d97d6f 69 * If the accumulator overflows it wraps around and distorts the result.
emh203 0:3d9c67d97d6f 70 * In order to avoid overflows completely the input signal must be scaled down by
emh203 0:3d9c67d97d6f 71 * log2(blockSize)-8 bits, as a total of blockSize additions are performed internally.
emh203 0:3d9c67d97d6f 72 * After division, internal variables should be Q18.46
emh203 0:3d9c67d97d6f 73 * Finally, the 18.46 accumulator is right shifted by 15 bits to yield a 1.31 format value.
emh203 0:3d9c67d97d6f 74 *
emh203 0:3d9c67d97d6f 75 */
emh203 0:3d9c67d97d6f 76
emh203 0:3d9c67d97d6f 77
emh203 0:3d9c67d97d6f 78 void arm_var_q31(
emh203 0:3d9c67d97d6f 79 q31_t * pSrc,
emh203 0:3d9c67d97d6f 80 uint32_t blockSize,
emh203 0:3d9c67d97d6f 81 q31_t * pResult)
emh203 0:3d9c67d97d6f 82 {
emh203 0:3d9c67d97d6f 83 q63_t sum = 0; /* Accumulator */
emh203 0:3d9c67d97d6f 84 q63_t meanOfSquares, squareOfMean; /* square of mean and mean of square */
emh203 0:3d9c67d97d6f 85 q31_t in; /* input value */
emh203 0:3d9c67d97d6f 86 uint32_t blkCnt; /* loop counter */
emh203 0:3d9c67d97d6f 87 q63_t sumOfSquares = 0; /* Accumulator */
emh203 0:3d9c67d97d6f 88
emh203 0:3d9c67d97d6f 89 if(blockSize == 1)
emh203 0:3d9c67d97d6f 90 {
emh203 0:3d9c67d97d6f 91 *pResult = 0;
emh203 0:3d9c67d97d6f 92 return;
emh203 0:3d9c67d97d6f 93 }
emh203 0:3d9c67d97d6f 94
emh203 0:3d9c67d97d6f 95 #ifndef ARM_MATH_CM0_FAMILY
emh203 0:3d9c67d97d6f 96
emh203 0:3d9c67d97d6f 97 /* Run the below code for Cortex-M4 and Cortex-M3 */
emh203 0:3d9c67d97d6f 98
emh203 0:3d9c67d97d6f 99 /*loop Unrolling */
emh203 0:3d9c67d97d6f 100 blkCnt = blockSize >> 2u;
emh203 0:3d9c67d97d6f 101
emh203 0:3d9c67d97d6f 102 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emh203 0:3d9c67d97d6f 103 ** a second loop below computes the remaining 1 to 3 samples. */
emh203 0:3d9c67d97d6f 104 while(blkCnt > 0u)
emh203 0:3d9c67d97d6f 105 {
emh203 0:3d9c67d97d6f 106 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
emh203 0:3d9c67d97d6f 107 /* Compute Sum of squares of the input samples
emh203 0:3d9c67d97d6f 108 * and then store the result in a temporary variable, sum. */
emh203 0:3d9c67d97d6f 109 in = *pSrc++ >> 8;
emh203 0:3d9c67d97d6f 110 sum += in;
emh203 0:3d9c67d97d6f 111 sumOfSquares += ((q63_t) (in) * (in));
emh203 0:3d9c67d97d6f 112 in = *pSrc++ >> 8;
emh203 0:3d9c67d97d6f 113 sum += in;
emh203 0:3d9c67d97d6f 114 sumOfSquares += ((q63_t) (in) * (in));
emh203 0:3d9c67d97d6f 115 in = *pSrc++ >> 8;
emh203 0:3d9c67d97d6f 116 sum += in;
emh203 0:3d9c67d97d6f 117 sumOfSquares += ((q63_t) (in) * (in));
emh203 0:3d9c67d97d6f 118 in = *pSrc++ >> 8;
emh203 0:3d9c67d97d6f 119 sum += in;
emh203 0:3d9c67d97d6f 120 sumOfSquares += ((q63_t) (in) * (in));
emh203 0:3d9c67d97d6f 121
emh203 0:3d9c67d97d6f 122 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 123 blkCnt--;
emh203 0:3d9c67d97d6f 124 }
emh203 0:3d9c67d97d6f 125
emh203 0:3d9c67d97d6f 126 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emh203 0:3d9c67d97d6f 127 ** No loop unrolling is used. */
emh203 0:3d9c67d97d6f 128 blkCnt = blockSize % 0x4u;
emh203 0:3d9c67d97d6f 129
emh203 0:3d9c67d97d6f 130 while(blkCnt > 0u)
emh203 0:3d9c67d97d6f 131 {
emh203 0:3d9c67d97d6f 132 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
emh203 0:3d9c67d97d6f 133 /* Compute Sum of squares of the input samples
emh203 0:3d9c67d97d6f 134 * and then store the result in a temporary variable, sum. */
emh203 0:3d9c67d97d6f 135 in = *pSrc++ >> 8;
emh203 0:3d9c67d97d6f 136 sum += in;
emh203 0:3d9c67d97d6f 137 sumOfSquares += ((q63_t) (in) * (in));
emh203 0:3d9c67d97d6f 138
emh203 0:3d9c67d97d6f 139 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 140 blkCnt--;
emh203 0:3d9c67d97d6f 141 }
emh203 0:3d9c67d97d6f 142
emh203 0:3d9c67d97d6f 143 /* Compute Mean of squares of the input samples
emh203 0:3d9c67d97d6f 144 * and then store the result in a temporary variable, meanOfSquares. */
emh203 0:3d9c67d97d6f 145 meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1);
emh203 0:3d9c67d97d6f 146
emh203 0:3d9c67d97d6f 147 #else
emh203 0:3d9c67d97d6f 148
emh203 0:3d9c67d97d6f 149 /* Run the below code for Cortex-M0 */
emh203 0:3d9c67d97d6f 150
emh203 0:3d9c67d97d6f 151 /* Loop over blockSize number of values */
emh203 0:3d9c67d97d6f 152 blkCnt = blockSize;
emh203 0:3d9c67d97d6f 153
emh203 0:3d9c67d97d6f 154 while(blkCnt > 0u)
emh203 0:3d9c67d97d6f 155 {
emh203 0:3d9c67d97d6f 156 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
emh203 0:3d9c67d97d6f 157 /* Compute Sum of squares of the input samples
emh203 0:3d9c67d97d6f 158 * and then store the result in a temporary variable, sumOfSquares. */
emh203 0:3d9c67d97d6f 159 in = *pSrc++ >> 8;
emh203 0:3d9c67d97d6f 160 sumOfSquares += ((q63_t) (in) * (in));
emh203 0:3d9c67d97d6f 161
emh203 0:3d9c67d97d6f 162 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
emh203 0:3d9c67d97d6f 163 /* Compute sum of all input values and then store the result in a temporary variable, sum. */
emh203 0:3d9c67d97d6f 164 sum += in;
emh203 0:3d9c67d97d6f 165
emh203 0:3d9c67d97d6f 166 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 167 blkCnt--;
emh203 0:3d9c67d97d6f 168 }
emh203 0:3d9c67d97d6f 169
emh203 0:3d9c67d97d6f 170 /* Compute Mean of squares of the input samples
emh203 0:3d9c67d97d6f 171 * and then store the result in a temporary variable, meanOfSquares. */
emh203 0:3d9c67d97d6f 172 meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1);
emh203 0:3d9c67d97d6f 173
emh203 0:3d9c67d97d6f 174 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
emh203 0:3d9c67d97d6f 175
emh203 0:3d9c67d97d6f 176 /* Compute square of mean */
emh203 0:3d9c67d97d6f 177 squareOfMean = sum * sum / (q63_t)(blockSize * (blockSize - 1u));
emh203 0:3d9c67d97d6f 178
emh203 0:3d9c67d97d6f 179
emh203 0:3d9c67d97d6f 180 /* Compute standard deviation and then store the result to the destination */
emh203 0:3d9c67d97d6f 181 *pResult = (meanOfSquares - squareOfMean) >> 15;
emh203 0:3d9c67d97d6f 182
emh203 0:3d9c67d97d6f 183 }
emh203 0:3d9c67d97d6f 184
emh203 0:3d9c67d97d6f 185 /**
emh203 0:3d9c67d97d6f 186 * @} end of variance group
emh203 0:3d9c67d97d6f 187 */