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 Entropy Entropy
42
43 Computes the entropy of a distribution
44
45 */
46
47 /**
48 * @addtogroup Entropy
49 * @{
50 */
51
52
53 /**
54 * @brief Entropy
55 *
56 * @param[in] pSrcA Array of input values.
57 * @param[in] blockSize Number of samples in the input array.
58 * @return Entropy -Sum(p ln p)
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_f16.h"
66
arm_entropy_f16(const float16_t * pSrcA,uint32_t blockSize)67 float16_t arm_entropy_f16(const float16_t * pSrcA,uint32_t blockSize)
68 {
69 uint32_t blkCnt;
70 _Float16 accum=0.0f16,p;
71
72
73 blkCnt = blockSize;
74
75 f16x8_t vSum = vdupq_n_f16(0.0f);
76 /* Compute 4 outputs at a time */
77 blkCnt = blockSize >> 3U;
78
79 while (blkCnt > 0U)
80 {
81 f16x8_t vecIn = vld1q(pSrcA);
82
83 vSum = vaddq_f16(vSum, vmulq(vecIn, vlogq_f16(vecIn)));
84
85 /*
86 * Decrement the blockSize loop counter
87 * Advance vector source and destination pointers
88 */
89 pSrcA += 8;
90 blkCnt --;
91 }
92
93 accum = vecAddAcrossF16Mve(vSum);
94
95 /* Tail */
96 blkCnt = blockSize & 0x7;
97 while(blkCnt > 0)
98 {
99 p = *pSrcA++;
100 accum += p * logf(p);
101
102 blkCnt--;
103
104 }
105
106 return (-accum);
107 }
108
109 #else
110
arm_entropy_f16(const float16_t * pSrcA,uint32_t blockSize)111 float16_t arm_entropy_f16(const float16_t * pSrcA,uint32_t blockSize)
112 {
113 const float16_t *pIn;
114 uint32_t blkCnt;
115 _Float16 accum, p;
116
117 pIn = pSrcA;
118 blkCnt = blockSize;
119
120 accum = 0.0f;
121
122 while(blkCnt > 0)
123 {
124 p = *pIn++;
125 accum += p * logf(p);
126
127 blkCnt--;
128
129 }
130
131 return(-accum);
132 }
133 #endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
134
135 /**
136 * @} end of Entropy group
137 */
138
139 #endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
140
141
