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1 /**
2  * Copyright 2020 Huawei Technologies Co., Ltd
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "nnacl/nnacl_common.h"
18 
19 typedef union float32_bits {
20   unsigned int u;
21   float f;
22 } float32_bits;
23 
ShortToFloat32(uint16_t src_value)24 float ShortToFloat32(uint16_t src_value) {
25   const float32_bits magic = {113 << 23};
26   const unsigned int shifted_exp = 0x7c00 << 13;
27   float32_bits o;
28 
29   o.u = (src_value & 0x7fff) << 13;
30   unsigned int exp = shifted_exp & o.u;
31   o.u += (127 - 15) << 23;
32 
33   if (exp == shifted_exp) {
34     o.u += (128 - 16) << 23;
35   } else if (exp == 0) {
36     o.u += 1 << 23;
37     o.f -= magic.f;
38   }
39 
40   o.u |= (src_value & 0x8000) << 16;
41   return o.f;
42 }
43 
Float32ToShort(float src_value)44 uint16_t Float32ToShort(float src_value) {
45   float32_bits src_value_bits;
46   src_value_bits.f = src_value;
47   uint16_t res = 0;
48   // mantissa
49   res += (src_value_bits.u >> 13);
50   // exponent
51   res += (src_value_bits.u >> 13) & 0x3fc00;
52   res -= (127 - 15) << 13;
53 
54   // sign
55   res |= (src_value_bits.u & 0x80000000) >> 16;
56   return res;
57 }
58