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git.gir.st - tmk_keyboard.git/blob - tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_power_q15.c
1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
8 * Title: arm_power_q15.c
10 * Description: Sum of the squares of the elements of a Q15 vector.
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
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 * -------------------------------------------------------------------- */
53 * @brief Sum of the squares 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 sum of the squares value returned here
60 * <b>Scaling and Overflow Behavior:</b>
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 return result is in 34.30 format.
78 q63_t sum
= 0; /* Temporary result storage */
80 #ifndef ARM_MATH_CM0_FAMILY
82 /* Run the below code for Cortex-M4 and Cortex-M3 */
84 q31_t in32
; /* Temporary variable to store input value */
85 q15_t in16
; /* Temporary variable to store input value */
86 uint32_t blkCnt
; /* loop counter */
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 Power and then store the result in a temporary variable, sum. */
98 in32
= *__SIMD32(pSrc
)++;
99 sum
= __SMLALD(in32
, in32
, sum
);
100 in32
= *__SIMD32(pSrc
)++;
101 sum
= __SMLALD(in32
, in32
, sum
);
103 /* Decrement the loop counter */
107 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
108 ** No loop unrolling is used. */
109 blkCnt
= blockSize
% 0x4u
;
113 /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
114 /* Compute Power and then store the result in a temporary variable, sum. */
116 sum
= __SMLALD(in16
, in16
, sum
);
118 /* Decrement the loop counter */
124 /* Run the below code for Cortex-M0 */
126 q15_t in
; /* Temporary variable to store input value */
127 uint32_t blkCnt
; /* loop counter */
130 /* Loop over blockSize number of values */
135 /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
136 /* Compute Power and then store the result in a temporary variable, sum. */
138 sum
+= ((q31_t
) in
* in
);
140 /* Decrement the loop counter */
144 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
146 /* Store the results in 34.30 format */
151 * @} end of power group