1
2 /* ----------------------------------------------------------------------
3 * Project: CMSIS DSP Library
4 * Title: arm_chebyshev_distance_f16.c
5 * Description: Chebyshev distance between two vectors
6 *
7 * $Date: 23 April 2021
8 * $Revision: V1.9.0
9 *
10 * Target Processor: Cortex-M and Cortex-A cores
11 * -------------------------------------------------------------------- */
12 /*
13 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
14 *
15 * SPDX-License-Identifier: Apache-2.0
16 *
17 * Licensed under the Apache License, Version 2.0 (the License); you may
18 * not use this file except in compliance with the License.
19 * You may obtain a copy of the License at
20 *
21 * www.apache.org/licenses/LICENSE-2.0
22 *
23 * Unless required by applicable law or agreed to in writing, software
24 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
25 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
26 * See the License for the specific language governing permissions and
27 * limitations under the License.
28 */
29
30 #include "dsp/distance_functions_f16.h"
31
32 #if defined(ARM_FLOAT16_SUPPORTED)
33
34 #include <limits.h>
35 #include <math.h>
36
37 /**
38 @ingroup FloatDist
39 */
40
41 /**
42 @defgroup Chebyshev Chebyshev distance
43
44 Chebyshev distance
45 */
46
47 /**
48 @addtogroup Chebyshev
49 @{
50 */
51
52
53 /**
54 * @brief Chebyshev distance between two vectors
55 * @param[in] pA First vector
56 * @param[in] pB Second vector
57 * @param[in] blockSize vector length
58 * @return distance
59 *
60 */
61
62 #if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE)
63
64 #include "arm_helium_utils.h"
65 #include "arm_vec_math.h"
66
arm_chebyshev_distance_f16(const float16_t * pA,const float16_t * pB,uint32_t blockSize)67 float16_t arm_chebyshev_distance_f16(const float16_t *pA,const float16_t *pB, uint32_t blockSize)
68 {
69 uint32_t blkCnt; /* loop counters */
70 f16x8_t vecA, vecB;
71 f16x8_t vecDiff = vdupq_n_f16(0.0);
72 float16_t maxValue = 0.0f16;
73
74
75 blkCnt = blockSize >> 3;
76 while (blkCnt > 0U) {
77 vecA = vld1q(pA);
78 pA += 8;
79 vecB = vld1q(pB);
80 pB += 8;
81 /*
82 * update per-lane max.
83 */
84 vecDiff = vmaxnmaq(vsubq(vecA, vecB), vecDiff);
85 /*
86 * Decrement the blockSize loop counter
87 */
88 blkCnt--;
89 }
90 /*
91 * tail
92 * (will be merged thru tail predication)
93 */
94 blkCnt = blockSize & 7;
95 if (blkCnt > 0U) {
96 mve_pred16_t p0 = vctp16q(blkCnt);
97
98 vecA = vldrhq_z_f16(pA, p0);
99 vecB = vldrhq_z_f16(pB, p0);
100
101 /*
102 * Get current max per lane and current index per lane
103 * when a max is selected
104 */
105 vecDiff = vmaxnmaq_m(vecDiff, vsubq(vecA, vecB), p0);
106 }
107 /*
108 * Get max value across the vector
109 */
110 return vmaxnmavq(maxValue, vecDiff);
111 }
112
113 #else
arm_chebyshev_distance_f16(const float16_t * pA,const float16_t * pB,uint32_t blockSize)114 float16_t arm_chebyshev_distance_f16(const float16_t *pA,const float16_t *pB, uint32_t blockSize)
115 {
116 _Float16 diff=0.0f, maxVal,tmpA, tmpB;
117
118 tmpA = *pA++;
119 tmpB = *pB++;
120 diff = fabsf(tmpA - tmpB);
121 maxVal = diff;
122 blockSize--;
123
124 while(blockSize > 0)
125 {
126 tmpA = *pA++;
127 tmpB = *pB++;
128 diff = fabsf(tmpA - tmpB);
129 if (diff > maxVal)
130 {
131 maxVal = diff;
132 }
133 blockSize --;
134 }
135
136 return(maxVal);
137 }
138 #endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
139
140
141 /**
142 * @} end of Chebyshev group
143 */
144
145 #endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
146
147
