1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
/*
* Copyright (C) 2010-2020 Arm Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* ----------------------------------------------------------------------
* Project: CMSIS NN Library
* Title: arm_softmax_u8.c
* Description: U8 softmax function
*
* $Date: 09. October 2020
* $Revision: V.1.0.2
*
* Target Processor: Cortex-M CPUs
*
* -------------------------------------------------------------------- */
#include "arm_nnfunctions.h"
#include "arm_nnsupportfunctions.h"
#define ACCUM_BITS 12
/**
* @ingroup groupNN
*/
/**
* @addtogroup Softmax
* @{
*/
void arm_softmax_u8(const uint8_t *input,
const int32_t num_rows,
const int32_t row_size,
const int32_t mult,
const int32_t shift,
const int32_t diff_min,
uint8_t *output)
{
const int32_t mask = (1 << shift);
int32_t col = 0;
int32_t row_idx;
for (row_idx = 0; row_idx < num_rows; ++row_idx)
{
// Find the maximum value in order to ensure numerical stability
uint8_t max = *input;
for (col = 1; col < row_size; ++col)
{
max = MAX(max, input[col]);
}
int32_t diff = 0;
int32_t sum = 0;
for (col = 0; col < row_size; ++col)
{
diff = input[col] - max;
if (diff >= diff_min)
{
sum += DIV_POW2(EXP_ON_NEG(MUL_SAT(diff * mask, mult)), ACCUM_BITS);
}
}
const int32_t headroom = __CLZ((uint32_t)sum);
const int32_t bits_over_unit = ACCUM_BITS - headroom + 23;
const int32_t shifted_scale = ONE_OVER1((sum << headroom) - (1 << 31));
for (col = 0; col < row_size; ++col)
{
diff = input[col] - max;
if (diff >= diff_min)
{
const int32_t res =
DIV_POW2(MUL_SAT(shifted_scale, EXP_ON_NEG(MUL_SAT(diff * mask, mult))), bits_over_unit);
output[col] = (uint8_t)CLAMP(res, (int32_t)255, (int32_t)0);
}
else
{
output[col] = 0;
}
}
input += row_size;
output += row_size;
}
}
/**
* @} end of Softmax group
*/
|
