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 18 namespace sw 19 { 20 class half 21 { 22 public: 23 half() = default; 24 half(const half& h) = default; 25 explicit half(float f); 26 27 operator float() const; 28 29 half &operator=(const half& h) = default; 30 half &operator=(float f); 31 32 private: 33 unsigned short fp16i; 34 }; 35 shortAsHalf(short s)36 inline half shortAsHalf(short s) 37 { 38 union 39 { 40 half h; 41 short s; 42 } hs; 43 44 hs.s = s; 45 46 return hs.h; 47 } 48 49 class RGB9E5 50 { 51 unsigned int R : 9; 52 unsigned int G : 9; 53 unsigned int B : 9; 54 unsigned int E : 5; 55 56 public: toRGB16F(half rgb[3]) const57 void toRGB16F(half rgb[3]) const 58 { 59 constexpr int offset = 24; // Exponent bias (15) + number of mantissa bits per component (9) = 24 60 61 const float factor = (1u << E) * (1.0f / (1 << offset)); 62 rgb[0] = half(R * factor); 63 rgb[1] = half(G * factor); 64 rgb[2] = half(B * factor); 65 } 66 }; 67 68 class R11G11B10F 69 { 70 unsigned int R : 11; 71 unsigned int G : 11; 72 unsigned int B : 10; 73 float11ToFloat16(unsigned short fp11)74 static inline half float11ToFloat16(unsigned short fp11) 75 { 76 return shortAsHalf(fp11 << 4); // Sign bit 0 77 } 78 float10ToFloat16(unsigned short fp10)79 static inline half float10ToFloat16(unsigned short fp10) 80 { 81 return shortAsHalf(fp10 << 5); // Sign bit 0 82 } 83 84 public: toRGB16F(half rgb[3]) const85 void toRGB16F(half rgb[3]) const 86 { 87 rgb[0] = float11ToFloat16(R); 88 rgb[1] = float11ToFloat16(G); 89 rgb[2] = float10ToFloat16(B); 90 } 91 }; 92 } 93 94 #endif // sw_Half_hpp 95