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#ifndef sw_Half_hpp
16#define sw_Half_hpp
17
18namespace sw
19{
20 class half
21 {
22 public:
23 half() = default;
24 explicit half(float f);
25
26 operator float() const;
27
28 half &operator=(half h);
29 half &operator=(float f);
30
31 private:
32 unsigned short fp16i;
33 };
34
35 inline half shortAsHalf(short s)
36 {
37 union
38 {
39 half h;
40 short s;
41 } hs;
42
43 hs.s = s;
44
45 return hs.h;
46 }
47
48 class RGB9E5
49 {
50 unsigned int R : 9;
51 unsigned int G : 9;
52 unsigned int B : 9;
53 unsigned int E : 5;
54
55 public:
56 void toRGB16F(half rgb[3]) const
57 {
58 constexpr int offset = 24; // Exponent bias (15) + number of mantissa bits per component (9) = 24
59
60 const float factor = (1u << E) * (1.0f / (1 << offset));
61 rgb[0] = half(R * factor);
62 rgb[1] = half(G * factor);
63 rgb[2] = half(B * factor);
64 }
65 };
66
67 class R11G11B10F
68 {
69 unsigned int R : 11;
70 unsigned int G : 11;
71 unsigned int B : 10;
72
73 static inline half float11ToFloat16(unsigned short fp11)
74 {
75 return shortAsHalf(fp11 << 4); // Sign bit 0
76 }
77
78 static inline half float10ToFloat16(unsigned short fp10)
79 {
80 return shortAsHalf(fp10 << 5); // Sign bit 0
81 }
82
83 public:
84 void toRGB16F(half rgb[3]) const
85 {
86 rgb[0] = float11ToFloat16(R);
87 rgb[1] = float11ToFloat16(G);
88 rgb[2] = float10ToFloat16(B);
89 }
90 };
91}
92
93#endif // sw_Half_hpp
94