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 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
