1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_max_q15.c
4 * Description: Maximum value of a Q15 vector
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/statistics_functions.h"
30
31 /**
32 @ingroup groupStats
33 */
34
35 /**
36 @addtogroup Max
37 @{
38 */
39
40 /**
41 @brief Maximum value of a Q15 vector.
42 @param[in] pSrc points to the input vector
43 @param[in] blockSize number of samples in input vector
44 @param[out] pResult maximum value returned here
45 @param[out] pIndex index of maximum value returned here
46 @return none
47 */
48 #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
49
50 #include "arm_helium_utils.h"
51
arm_max_q15(const q15_t * pSrc,uint32_t blockSize,q15_t * pResult,uint32_t * pIndex)52 void arm_max_q15(
53 const q15_t * pSrc,
54 uint32_t blockSize,
55 q15_t * pResult,
56 uint32_t * pIndex)
57 {
58 int32_t blkCnt; /* loop counters */
59 q15x8_t extremValVec = vdupq_n_s16(Q15_MIN);
60 q15_t maxValue = Q15_MIN;
61 uint16x8_t indexVec;
62 uint16x8_t extremIdxVec;
63 mve_pred16_t p0;
64 uint16_t extremIdxArr[8];
65
66 indexVec = vidupq_u16(0U, 1);
67
68 blkCnt = blockSize;
69 do {
70 mve_pred16_t p = vctp16q(blkCnt);
71 q15x8_t extremIdxVal = vld1q_z_s16(pSrc, p);
72 /*
73 * Get current max per lane and current index per lane
74 * when a max is selected
75 */
76 p0 = vcmpgeq_m(extremIdxVal, extremValVec, p);
77
78 extremValVec = vorrq_m(extremValVec, extremIdxVal, extremIdxVal, p0);
79 /* store per-lane extrema indexes */
80 vst1q_p_u16(extremIdxArr, indexVec, p0);
81
82 indexVec += 8;
83 pSrc += 8;
84 blkCnt -= 8;
85 }
86 while (blkCnt > 0);
87
88
89 /* Get max value across the vector */
90 maxValue = vmaxvq(maxValue, extremValVec);
91
92 /* set index for lower values to max possible index */
93 p0 = vcmpgeq(extremValVec, maxValue);
94 extremIdxVec = vld1q_u16(extremIdxArr);
95
96 indexVec = vpselq(extremIdxVec, vdupq_n_u16(blockSize - 1), p0);
97 *pIndex = vminvq(blockSize - 1, indexVec);
98 *pResult = maxValue;
99 }
100
101 #else
arm_max_q15(const q15_t * pSrc,uint32_t blockSize,q15_t * pResult,uint32_t * pIndex)102 void arm_max_q15(
103 const q15_t * pSrc,
104 uint32_t blockSize,
105 q15_t * pResult,
106 uint32_t * pIndex)
107 {
108 q15_t maxVal, out; /* Temporary variables to store the output value. */
109 uint32_t blkCnt, outIndex; /* Loop counter */
110
111 #if defined (ARM_MATH_LOOPUNROLL)
112 uint32_t index; /* index of maximum value */
113 #endif
114
115 /* Initialise index value to zero. */
116 outIndex = 0U;
117 /* Load first input value that act as reference value for comparision */
118 out = *pSrc++;
119
120 #if defined (ARM_MATH_LOOPUNROLL)
121 /* Initialise index of maximum value. */
122 index = 0U;
123
124 /* Loop unrolling: Compute 4 outputs at a time */
125 blkCnt = (blockSize - 1U) >> 2U;
126
127 while (blkCnt > 0U)
128 {
129 /* Initialize maxVal to next consecutive values one by one */
130 maxVal = *pSrc++;
131
132 /* compare for the maximum value */
133 if (out < maxVal)
134 {
135 /* Update the maximum value and it's index */
136 out = maxVal;
137 outIndex = index + 1U;
138 }
139
140 maxVal = *pSrc++;
141 if (out < maxVal)
142 {
143 out = maxVal;
144 outIndex = index + 2U;
145 }
146
147 maxVal = *pSrc++;
148 if (out < maxVal)
149 {
150 out = maxVal;
151 outIndex = index + 3U;
152 }
153
154 maxVal = *pSrc++;
155 if (out < maxVal)
156 {
157 out = maxVal;
158 outIndex = index + 4U;
159 }
160
161 index += 4U;
162
163 /* Decrement loop counter */
164 blkCnt--;
165 }
166
167 /* Loop unrolling: Compute remaining outputs */
168 blkCnt = (blockSize - 1U) % 4U;
169
170 #else
171
172 /* Initialize blkCnt with number of samples */
173 blkCnt = (blockSize - 1U);
174
175 #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
176
177 while (blkCnt > 0U)
178 {
179 /* Initialize maxVal to the next consecutive values one by one */
180 maxVal = *pSrc++;
181
182 /* compare for the maximum value */
183 if (out < maxVal)
184 {
185 /* Update the maximum value and it's index */
186 out = maxVal;
187 outIndex = blockSize - blkCnt;
188 }
189
190 /* Decrement loop counter */
191 blkCnt--;
192 }
193
194 /* Store the maximum value and it's index into destination pointers */
195 *pResult = out;
196 *pIndex = outIndex;
197 }
198 #endif /* defined(ARM_MATH_MVEI) */
199 /**
200 @} end of Max group
201 */
202
