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git.gir.st - tmk_keyboard.git/blob - tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_rms_f32.c
1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
10 * Description: Root mean square value of an array of F32 type
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
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
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.
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
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37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 * ---------------------------------------------------------------------------- */
48 * @defgroup RMS Root mean square (RMS)
51 * Calculates the Root Mean Sqaure of the elements in the input vector.
52 * The underlying algorithm is used:
55 * Result = sqrt(((pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]) / blockSize));
58 * There are separate functions for floating point, Q31, and Q15 data types.
68 * @brief Root Mean Square of the elements of a floating-point vector.
69 * @param[in] *pSrc points to the input vector
70 * @param[in] blockSize length of the input vector
71 * @param[out] *pResult rms value returned here
81 float32_t sum
= 0.0f
; /* Accumulator */
82 float32_t in
; /* Tempoprary variable to store input value */
83 uint32_t blkCnt
; /* loop counter */
85 #ifndef ARM_MATH_CM0_FAMILY
87 /* Run the below code for Cortex-M4 and Cortex-M3 */
90 blkCnt
= blockSize
>> 2u;
92 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
93 ** a second loop below computes the remaining 1 to 3 samples. */
96 /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
97 /* Compute sum of the squares and then store the result in a temporary variable, sum */
107 /* Decrement the loop counter */
111 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
112 ** No loop unrolling is used. */
113 blkCnt
= blockSize
% 0x4u
;
117 /* Run the below code for Cortex-M0 */
119 /* Loop over blockSize number of values */
122 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
126 /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
127 /* Compute sum of the squares and then store the results in a temporary variable, sum */
131 /* Decrement the loop counter */
135 /* Compute Rms and store the result in the destination */
136 arm_sqrt_f32(sum
/ (float32_t
) blockSize
, pResult
);
140 * @} end of RMS group