source: S-port/trunk/Drivers/CMSIS/DSP/Source/BasicMathFunctions/arm_sub_q31.c

Last change on this file was 1, checked in by AlexLir, 3 years ago
File size: 3.5 KB
Line 
1/* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_sub_q31.c
4 * Description: Q31 vector subtraction
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 BasicSub
37 * @{
38 */
39
40/**
41 * @brief Q31 vector subtraction.
42 * @param[in] *pSrcA points to the first input vector
43 * @param[in] *pSrcB points to the second input vector
44 * @param[out] *pDst points to the output vector
45 * @param[in] blockSize number of samples in each vector
46 * @return none.
47 *
48 * <b>Scaling and Overflow Behavior:</b>
49 * \par
50 * The function uses saturating arithmetic.
51 * Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated.
52 */
53
54void arm_sub_q31(
55 q31_t * pSrcA,
56 q31_t * pSrcB,
57 q31_t * pDst,
58 uint32_t blockSize)
59{
60 uint32_t blkCnt; /* loop counter */
61
62
63#if defined (ARM_MATH_DSP)
64
65/* Run the below code for Cortex-M4 and Cortex-M3 */
66 q31_t inA1, inA2, inA3, inA4;
67 q31_t inB1, inB2, inB3, inB4;
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 while (blkCnt > 0U)
75 {
76 /* C = A - B */
77 /* Subtract and then store the results in the destination buffer. */
78 inA1 = *pSrcA++;
79 inA2 = *pSrcA++;
80 inB1 = *pSrcB++;
81 inB2 = *pSrcB++;
82
83 inA3 = *pSrcA++;
84 inA4 = *pSrcA++;
85 inB3 = *pSrcB++;
86 inB4 = *pSrcB++;
87
88 *pDst++ = __QSUB(inA1, inB1);
89 *pDst++ = __QSUB(inA2, inB2);
90 *pDst++ = __QSUB(inA3, inB3);
91 *pDst++ = __QSUB(inA4, inB4);
92
93 /* Decrement the loop counter */
94 blkCnt--;
95 }
96
97 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
98 ** No loop unrolling is used. */
99 blkCnt = blockSize % 0x4U;
100
101 while (blkCnt > 0U)
102 {
103 /* C = A - B */
104 /* Subtract and then store the result in the destination buffer. */
105 *pDst++ = __QSUB(*pSrcA++, *pSrcB++);
106
107 /* Decrement the loop counter */
108 blkCnt--;
109 }
110
111#else
112
113 /* Run the below code for Cortex-M0 */
114
115 /* Initialize blkCnt with number of samples */
116 blkCnt = blockSize;
117
118 while (blkCnt > 0U)
119 {
120 /* C = A - B */
121 /* Subtract and then store the result in the destination buffer. */
122 *pDst++ = (q31_t) clip_q63_to_q31((q63_t) * pSrcA++ - *pSrcB++);
123
124 /* Decrement the loop counter */
125 blkCnt--;
126 }
127
128#endif /* #if defined (ARM_MATH_DSP) */
129
130}
131
132/**
133 * @} end of BasicSub group
134 */
Note: See TracBrowser for help on using the repository browser.