1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_sub_q7.c
4 * Description: Q7 vector subtraction
5 *
6 * $Date: 23 April 2021
7 * $Revision: V1.9.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2021 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 "dsp/basic_math_functions.h"
30
31 /**
32 @ingroup groupMath
33 */
34
35 /**
36 @addtogroup BasicSub
37 @{
38 */
39
40 /**
41 @brief Q7 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 @par Scaling and Overflow Behavior
49 The function uses saturating arithmetic.
50 Results outside of the allowable Q7 range [0x80 0x7F] will be saturated.
51 */
52 #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
53
54 #include "arm_helium_utils.h"
55
arm_sub_q7(const q7_t * pSrcA,const q7_t * pSrcB,q7_t * pDst,uint32_t blockSize)56 void arm_sub_q7(
57 const q7_t * pSrcA,
58 const q7_t * pSrcB,
59 q7_t * pDst,
60 uint32_t blockSize)
61 {
62 uint32_t blkCnt; /* loop counters */
63 q7x16_t vecA;
64 q7x16_t vecB;
65
66 /* Compute 16 outputs at a time */
67 blkCnt = blockSize >> 4;
68 while (blkCnt > 0U)
69 {
70 /*
71 * C = A - B
72 * Subtract and then store the results in the destination buffer.
73 */
74 vecA = vld1q(pSrcA);
75 vecB = vld1q(pSrcB);
76 vst1q(pDst, vqsubq(vecA, vecB));
77 /*
78 * Decrement the blockSize loop counter
79 */
80 blkCnt--;
81 /*
82 * advance vector source and destination pointers
83 */
84 pSrcA += 16;
85 pSrcB += 16;
86 pDst += 16;
87 }
88 /*
89 * tail
90 */
91 blkCnt = blockSize & 0xF;
92 if (blkCnt > 0U)
93 {
94 mve_pred16_t p0 = vctp8q(blkCnt);
95 vecA = vld1q(pSrcA);
96 vecB = vld1q(pSrcB);
97 vstrbq_p(pDst, vqsubq(vecA, vecB), p0);
98 }
99 }
100 #else
arm_sub_q7(const q7_t * pSrcA,const q7_t * pSrcB,q7_t * pDst,uint32_t blockSize)101 void arm_sub_q7(
102 const q7_t * pSrcA,
103 const q7_t * pSrcB,
104 q7_t * pDst,
105 uint32_t blockSize)
106 {
107 uint32_t blkCnt; /* Loop counter */
108
109 #if defined (ARM_MATH_LOOPUNROLL)
110
111 /* Loop unrolling: Compute 4 outputs at a time */
112 blkCnt = blockSize >> 2U;
113
114 while (blkCnt > 0U)
115 {
116 /* C = A - B */
117
118 #if defined (ARM_MATH_DSP)
119 /* Subtract and store result in destination buffer (4 samples at a time). */
120 write_q7x4_ia (&pDst, __QSUB8(read_q7x4_ia ((q7_t **) &pSrcA), read_q7x4_ia ((q7_t **) &pSrcB)));
121 #else
122 *pDst++ = (q7_t) __SSAT((q15_t) *pSrcA++ - *pSrcB++, 8);
123 *pDst++ = (q7_t) __SSAT((q15_t) *pSrcA++ - *pSrcB++, 8);
124 *pDst++ = (q7_t) __SSAT((q15_t) *pSrcA++ - *pSrcB++, 8);
125 *pDst++ = (q7_t) __SSAT((q15_t) *pSrcA++ - *pSrcB++, 8);
126 #endif
127
128 /* Decrement loop counter */
129 blkCnt--;
130 }
131
132 /* Loop unrolling: Compute remaining outputs */
133 blkCnt = blockSize % 0x4U;
134
135 #else
136
137 /* Initialize blkCnt with number of samples */
138 blkCnt = blockSize;
139
140 #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
141
142 while (blkCnt > 0U)
143 {
144 /* C = A - B */
145
146 /* Subtract and store result in destination buffer. */
147 *pDst++ = (q7_t) __SSAT((q15_t) *pSrcA++ - *pSrcB++, 8);
148
149 /* Decrement loop counter */
150 blkCnt--;
151 }
152
153 }
154 #endif /* defined(ARM_MATH_MVEI) */
155
156 /**
157 @} end of BasicSub group
158 */
159
