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comparison f103c8/Drivers/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_f32.c @ 2:0c59e7a7782a

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Working on GPIO and RCC
author cin
date Mon, 16 Jan 2017 11:04:47 +0300
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1:a0b14b11ad9f 2:0c59e7a7782a
1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
3 *
4 * $Date: 19. March 2015
5 * $Revision: V.1.4.5
6 *
7 * Project: CMSIS DSP Library
8 * Title: arm_var_f32.c
9 *
10 * Description: Variance of the elements of a floating-point vector.
11 *
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * - Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * - Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in
21 * the documentation and/or other materials provided with the
22 * distribution.
23 * - Neither the name of ARM LIMITED nor the names of its contributors
24 * may be used to endorse or promote products derived from this
25 * software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 * ---------------------------------------------------------------------------- */
40
41 #include "arm_math.h"
42
43 /**
44 * @ingroup groupStats
45 */
46
47 /**
48 * @defgroup variance Variance
49 *
50 * Calculates the variance of the elements in the input vector.
51 * The underlying algorithm is used:
52 *
53 * <pre>
54 * Result = (sumOfSquares - sum<sup>2</sup> / blockSize) / (blockSize - 1)
55 *
56 * where, sumOfSquares = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]
57 *
58 * sum = pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]
59 * </pre>
60 *
61 * There are separate functions for floating point, Q31, and Q15 data types.
62 */
63
64 /**
65 * @addtogroup variance
66 * @{
67 */
68
69
70 /**
71 * @brief Variance of the elements of a floating-point vector.
72 * @param[in] *pSrc points to the input vector
73 * @param[in] blockSize length of the input vector
74 * @param[out] *pResult variance value returned here
75 * @return none.
76 *
77 */
78
79
80 void arm_var_f32(
81 float32_t * pSrc,
82 uint32_t blockSize,
83 float32_t * pResult)
84 {
85
86 float32_t sum = 0.0f; /* Temporary result storage */
87 float32_t sumOfSquares = 0.0f; /* Sum of squares */
88 float32_t in; /* input value */
89 uint32_t blkCnt; /* loop counter */
90
91 #ifndef ARM_MATH_CM0_FAMILY
92
93 /* Run the below code for Cortex-M4 and Cortex-M3 */
94
95 float32_t meanOfSquares, mean, squareOfMean; /* Temporary variables */
96
97 if(blockSize == 1)
98 {
99 *pResult = 0;
100 return;
101 }
102
103 /*loop Unrolling */
104 blkCnt = blockSize >> 2u;
105
106 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
107 ** a second loop below computes the remaining 1 to 3 samples. */
108 while(blkCnt > 0u)
109 {
110 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
111 /* Compute Sum of squares of the input samples
112 * and then store the result in a temporary variable, sum. */
113 in = *pSrc++;
114 sum += in;
115 sumOfSquares += in * in;
116 in = *pSrc++;
117 sum += in;
118 sumOfSquares += in * in;
119 in = *pSrc++;
120 sum += in;
121 sumOfSquares += in * in;
122 in = *pSrc++;
123 sum += in;
124 sumOfSquares += in * in;
125
126 /* Decrement the loop counter */
127 blkCnt--;
128 }
129
130 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
131 ** No loop unrolling is used. */
132 blkCnt = blockSize % 0x4u;
133
134 while(blkCnt > 0u)
135 {
136 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
137 /* Compute Sum of squares of the input samples
138 * and then store the result in a temporary variable, sum. */
139 in = *pSrc++;
140 sum += in;
141 sumOfSquares += in * in;
142
143 /* Decrement the loop counter */
144 blkCnt--;
145 }
146
147 /* Compute Mean of squares of the input samples
148 * and then store the result in a temporary variable, meanOfSquares. */
149 meanOfSquares = sumOfSquares / ((float32_t) blockSize - 1.0f);
150
151 /* Compute mean of all input values */
152 mean = sum / (float32_t) blockSize;
153
154 /* Compute square of mean */
155 squareOfMean = (mean * mean) * (((float32_t) blockSize) /
156 ((float32_t) blockSize - 1.0f));
157
158 /* Compute variance and then store the result to the destination */
159 *pResult = meanOfSquares - squareOfMean;
160
161 #else
162
163 /* Run the below code for Cortex-M0 */
164 float32_t squareOfSum; /* Square of Sum */
165
166 if(blockSize == 1)
167 {
168 *pResult = 0;
169 return;
170 }
171
172 /* Loop over blockSize number of values */
173 blkCnt = blockSize;
174
175 while(blkCnt > 0u)
176 {
177 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
178 /* Compute Sum of squares of the input samples
179 * and then store the result in a temporary variable, sumOfSquares. */
180 in = *pSrc++;
181 sumOfSquares += in * in;
182
183 /* C = (A[0] + A[1] + ... + A[blockSize-1]) */
184 /* Compute Sum of the input samples
185 * and then store the result in a temporary variable, sum. */
186 sum += in;
187
188 /* Decrement the loop counter */
189 blkCnt--;
190 }
191
192 /* Compute the square of sum */
193 squareOfSum = ((sum * sum) / (float32_t) blockSize);
194
195 /* Compute the variance */
196 *pResult = ((sumOfSquares - squareOfSum) / (float32_t) (blockSize - 1.0f));
197
198 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
199
200 }
201
202 /**
203 * @} end of variance group
204 */