source: S-port/trunk/Drivers/CMSIS/DSP/Source/BasicMathFunctions/arm_abs_q15.c

Last change on this file was 1, checked in by AlexLir, 3 years ago
File size: 4.3 KB
Line 
1/* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_abs_q15.c
4 * Description: Q15 vector absolute value
5 *
6 * $Date: 27. January 2017
7 * $Revision: V.1.5.1
8 *
9 * Target Processor: Cortex-M cores
10 * -------------------------------------------------------------------- */
11/*
12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29#include "arm_math.h"
30
31/**
32 * @ingroup groupMath
33 */
34
35/**
36 * @addtogroup BasicAbs
37 * @{
38 */
39
40/**
41 * @brief Q15 vector absolute value.
42 * @param[in] *pSrc points to the input buffer
43 * @param[out] *pDst points to the output buffer
44 * @param[in] blockSize number of samples in each vector
45 * @return none.
46 *
47 * <b>Scaling and Overflow Behavior:</b>
48 * \par
49 * The function uses saturating arithmetic.
50 * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.
51 */
52
53void arm_abs_q15(
54 q15_t * pSrc,
55 q15_t * pDst,
56 uint32_t blockSize)
57{
58 uint32_t blkCnt; /* loop counter */
59
60#if defined (ARM_MATH_DSP)
61 __SIMD32_TYPE *simd;
62
63/* Run the below code for Cortex-M4 and Cortex-M3 */
64
65 q15_t in1; /* Input value1 */
66 q15_t in2; /* Input value2 */
67
68
69 /*loop Unrolling */
70 blkCnt = blockSize >> 2U;
71
72 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
73 ** a second loop below computes the remaining 1 to 3 samples. */
74 simd = __SIMD32_CONST(pDst);
75 while (blkCnt > 0U)
76 {
77 /* C = |A| */
78 /* Read two inputs */
79 in1 = *pSrc++;
80 in2 = *pSrc++;
81
82
83 /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
84#ifndef ARM_MATH_BIG_ENDIAN
85 *simd++ =
86 __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
87 ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
88
89#else
90
91
92 *simd++ =
93 __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
94 ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
95
96#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
97
98 in1 = *pSrc++;
99 in2 = *pSrc++;
100
101
102#ifndef ARM_MATH_BIG_ENDIAN
103
104 *simd++ =
105 __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
106 ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
107
108#else
109
110
111 *simd++ =
112 __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
113 ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
114
115#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
116
117 /* Decrement the loop counter */
118 blkCnt--;
119 }
120 pDst = (q15_t *)simd;
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| */
129 /* Read the input */
130 in1 = *pSrc++;
131
132 /* Calculate absolute value of input and then store the result in the destination buffer. */
133 *pDst++ = (in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1);
134
135 /* Decrement the loop counter */
136 blkCnt--;
137 }
138
139#else
140
141 /* Run the below code for Cortex-M0 */
142
143 q15_t in; /* Temporary input variable */
144
145 /* Initialize blkCnt with number of samples */
146 blkCnt = blockSize;
147
148 while (blkCnt > 0U)
149 {
150 /* C = |A| */
151 /* Read the input */
152 in = *pSrc++;
153
154 /* Calculate absolute value of input and then store the result in the destination buffer. */
155 *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
156
157 /* Decrement the loop counter */
158 blkCnt--;
159 }
160
161#endif /* #if defined (ARM_MATH_DSP) */
162
163}
164
165/**
166 * @} end of BasicAbs group
167 */
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