Mercurial > pub > halpp

comparison f103c8/Drivers/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_q15.c @ 2:0c59e7a7782a

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Working on GPIO and RCC
author cin
date Mon, 16 Jan 2017 11:04:47 +0300
parents
children
comparison
equal deleted inserted replaced
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_q15.c
9 *
10 * Description: Variance of an array of Q15 type.
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 * @addtogroup variance
49 * @{
50 */
51
52 /**
53 * @brief Variance of the elements of a Q15 vector.
54 * @param[in] *pSrc points to the input vector
55 * @param[in] blockSize length of the input vector
56 * @param[out] *pResult variance value returned here
57 * @return none.
58 *
59 * @details
60 * <b>Scaling and Overflow Behavior:</b>
61 *
62 * \par
63 * The function is implemented using a 64-bit internal accumulator.
64 * The input is represented in 1.15 format.
65 * Intermediate multiplication yields a 2.30 format, and this
66 * result is added without saturation to a 64-bit accumulator in 34.30 format.
67 * With 33 guard bits in the accumulator, there is no risk of overflow, and the
68 * full precision of the intermediate multiplication is preserved.
69 * Finally, the 34.30 result is truncated to 34.15 format by discarding the lower
70 * 15 bits, and then saturated to yield a result in 1.15 format.
71 *
72 */
73
74
75 void arm_var_q15(
76 q15_t * pSrc,
77 uint32_t blockSize,
78 q15_t * pResult)
79 {
80
81 q31_t sum = 0; /* Accumulator */
82 q31_t meanOfSquares, squareOfMean; /* square of mean and mean of square */
83 uint32_t blkCnt; /* loop counter */
84 q63_t sumOfSquares = 0; /* Accumulator */
85
86 #ifndef ARM_MATH_CM0_FAMILY
87
88 /* Run the below code for Cortex-M4 and Cortex-M3 */
89
90 q31_t in; /* input value */
91 q15_t in1; /* input value */
92
93 if(blockSize == 1)
94 {
95 *pResult = 0;
96 return;
97 }
98
99 /*loop Unrolling */
100 blkCnt = blockSize >> 2u;
101
102 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
103 ** a second loop below computes the remaining 1 to 3 samples. */
104 while(blkCnt > 0u)
105 {
106 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
107 /* Compute Sum of squares of the input samples
108 * and then store the result in a temporary variable, sum. */
109 in = *__SIMD32(pSrc)++;
110 sum += ((in << 16) >> 16);
111 sum += (in >> 16);
112 sumOfSquares = __SMLALD(in, in, sumOfSquares);
113 in = *__SIMD32(pSrc)++;
114 sum += ((in << 16) >> 16);
115 sum += (in >> 16);
116 sumOfSquares = __SMLALD(in, in, sumOfSquares);
117
118 /* Decrement the loop counter */
119 blkCnt--;
120 }
121
122 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
123 ** No loop unrolling is used. */
124 blkCnt = blockSize % 0x4u;
125
126 while(blkCnt > 0u)
127 {
128 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
129 /* Compute Sum of squares of the input samples
130 * and then store the result in a temporary variable, sum. */
131 in1 = *pSrc++;
132 sumOfSquares = __SMLALD(in1, in1, sumOfSquares);
133 sum += in1;
134
135 /* Decrement the loop counter */
136 blkCnt--;
137 }
138
139 /* Compute Mean of squares of the input samples
140 * and then store the result in a temporary variable, meanOfSquares. */
141 meanOfSquares = (q31_t) (sumOfSquares / (q63_t)(blockSize - 1));
142
143 /* Compute square of mean */
144 squareOfMean = (q31_t)((q63_t)sum * sum / (q63_t)(blockSize * (blockSize - 1)));
145
146 /* mean of the squares minus the square of the mean. */
147 *pResult = (meanOfSquares - squareOfMean) >> 15;
148
149 #else
150
151 /* Run the below code for Cortex-M0 */
152 q15_t in; /* input value */
153
154 if(blockSize == 1)
155 {
156 *pResult = 0;
157 return;
158 }
159
160 /* Loop over blockSize number of values */
161 blkCnt = blockSize;
162
163 while(blkCnt > 0u)
164 {
165 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
166 /* Compute Sum of squares of the input samples
167 * and then store the result in a temporary variable, sumOfSquares. */
168 in = *pSrc++;
169 sumOfSquares += (in * in);
170
171 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
172 /* Compute sum of all input values and then store the result in a temporary variable, sum. */
173 sum += in;
174
175 /* Decrement the loop counter */
176 blkCnt--;
177 }
178
179 /* Compute Mean of squares of the input samples
180 * and then store the result in a temporary variable, meanOfSquares. */
181 meanOfSquares = (q31_t) (sumOfSquares / (q63_t)(blockSize - 1));
182
183 /* Compute square of mean */
184 squareOfMean = (q31_t)((q63_t)sum * sum / (q63_t)(blockSize * (blockSize - 1)));
185
186 /* mean of the squares minus the square of the mean. */
187 *pResult = (meanOfSquares - squareOfMean) >> 15;
188
189 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
190
191 }
192
193 /**
194 * @} end of variance group
195 */