1// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#include "Half.hpp"
16
17namespace sw
18{
19 half::half(float fp32)
20 {
21 unsigned int fp32i = *(unsigned int*)&fp32;
22 unsigned int sign = (fp32i & 0x80000000) >> 16;
23 unsigned int abs = fp32i & 0x7FFFFFFF;
24
25 if(abs > 0x47FFEFFF) // Infinity
26 {
27 fp16i = sign | 0x7FFF;
28 }
29 else if(abs < 0x38800000) // Denormal
30 {
31 unsigned int mantissa = (abs & 0x007FFFFF) | 0x00800000;
32 int e = 113 - (abs >> 23);
33
34 if(e < 24)
35 {
36 abs = mantissa >> e;
37 }
38 else
39 {
40 abs = 0;
41 }
42
43 fp16i = sign | (abs + 0x00000FFF + ((abs >> 13) & 1)) >> 13;
44 }
45 else
46 {
47 fp16i = sign | (abs + 0xC8000000 + 0x00000FFF + ((abs >> 13) & 1)) >> 13;
48 }
49 }
50
51 half::operator float() const
52 {
53 unsigned int fp32i;
54
55 int s = (fp16i >> 15) & 0x00000001;
56 int e = (fp16i >> 10) & 0x0000001F;
57 int m = fp16i & 0x000003FF;
58
59 if(e == 0)
60 {
61 if(m == 0)
62 {
63 fp32i = s << 31;
64
65 return (float&)fp32i;
66 }
67 else
68 {
69 while(!(m & 0x00000400))
70 {
71 m <<= 1;
72 e -= 1;
73 }
74
75 e += 1;
76 m &= ~0x00000400;
77 }
78 }
79
80 e = e + (127 - 15);
81 m = m << 13;
82
83 fp32i = (s << 31) | (e << 23) | m;
84
85 return (float&)fp32i;
86 }
87
88 half &half::operator=(half h)
89 {
90 fp16i = h.fp16i;
91
92 return *this;
93 }
94
95
96 half &half::operator=(float f)
97 {
98 *this = half(f);
99
100 return *this;
101 }
102}
103