1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_logsumexp_f16.c
4 * Description: LogSumExp
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_f16.h"
30
31 #if defined(ARM_FLOAT16_SUPPORTED)
32
33 #include <limits.h>
34 #include <math.h>
35
36 /**
37 @ingroup groupStats
38 */
39
40 /**
41 @defgroup Kullback-Leibler Kullback-Leibler divergence
42
43 Computes the Kullback-Leibler divergence between two distributions
44
45 */
46
47
48 /**
49 * @addtogroup Kullback-Leibler
50 * @{
51 */
52
53
54 /**
55 * @brief Kullback-Leibler
56 *
57 * Distribution A may contain 0 with Neon version.
58 * Result will be right but some exception flags will be set.
59 *
60 * Distribution B must not contain 0 probability.
61 *
62 * @param[in] *pSrcA points to an array of input values for probaility distribution A.
63 * @param[in] *pSrcB points to an array of input values for probaility distribution B.
64 * @param[in] blockSize number of samples in the input array.
65 * @return Kullback-Leibler divergence D(A || B)
66 *
67 */
68
69 #if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE)
70
71 #include "arm_helium_utils.h"
72 #include "arm_vec_math_f16.h"
73
arm_kullback_leibler_f16(const float16_t * pSrcA,const float16_t * pSrcB,uint32_t blockSize)74 float16_t arm_kullback_leibler_f16(const float16_t * pSrcA,const float16_t * pSrcB,uint32_t blockSize)
75 {
76 uint32_t blkCnt;
77 _Float16 accum, pA,pB;
78
79
80 blkCnt = blockSize;
81
82 accum = 0.0f16;
83
84 f16x8_t vSum = vdupq_n_f16(0.0f);
85 blkCnt = blockSize >> 3;
86 while(blkCnt > 0)
87 {
88 f16x8_t vecA = vld1q(pSrcA);
89 f16x8_t vecB = vld1q(pSrcB);
90 f16x8_t vRatio;
91
92 vRatio = vdiv_f16(vecB, vecA);
93 vSum = vaddq_f16(vSum, vmulq(vecA, vlogq_f16(vRatio)));
94
95 /*
96 * Decrement the blockSize loop counter
97 * Advance vector source and destination pointers
98 */
99 pSrcA += 8;
100 pSrcB += 8;
101 blkCnt --;
102 }
103
104 accum = vecAddAcrossF16Mve(vSum);
105
106 blkCnt = blockSize & 7;
107 while(blkCnt > 0)
108 {
109 pA = *pSrcA++;
110 pB = *pSrcB++;
111 accum += pA * logf(pB / pA);
112
113 blkCnt--;
114
115 }
116
117 return(-accum);
118 }
119
120 #else
arm_kullback_leibler_f16(const float16_t * pSrcA,const float16_t * pSrcB,uint32_t blockSize)121 float16_t arm_kullback_leibler_f16(const float16_t * pSrcA,const float16_t * pSrcB,uint32_t blockSize)
122 {
123 const float16_t *pInA, *pInB;
124 uint32_t blkCnt;
125 _Float16 accum, pA,pB;
126
127 pInA = pSrcA;
128 pInB = pSrcB;
129 blkCnt = blockSize;
130
131 accum = 0.0f;
132
133 while(blkCnt > 0)
134 {
135 pA = *pInA++;
136 pB = *pInB++;
137 accum += pA * logf(pB / pA);
138
139 blkCnt--;
140
141 }
142
143 return(-accum);
144 }
145 #endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
146
147 /**
148 * @} end of Kullback-Leibler group
149 */
150
151 #endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
152
153
