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| Rev | Author | Line No. | Line |
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| 5564 | serge | 1 | /* |
| 2 | * Copyright (C) 2011 Marek Olšák |
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| 3 | * |
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| 4 | * Permission is hereby granted, free of charge, to any person obtaining a |
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| 5 | * copy of this software and associated documentation files (the "Software"), |
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| 6 | * to deal in the Software without restriction, including without limitation |
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| 7 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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| 8 | * and/or sell copies of the Software, and to permit persons to whom the |
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| 9 | * Software is furnished to do so, subject to the following conditions: |
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| 10 | * |
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| 11 | * The above copyright notice and this permission notice (including the next |
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| 12 | * paragraph) shall be included in all copies or substantial portions of the |
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| 13 | * Software. |
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| 14 | * |
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| 15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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| 16 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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| 17 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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| 18 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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| 19 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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| 20 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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| 21 | * DEALINGS IN THE SOFTWARE. |
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| 22 | */ |
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| 23 | |||
| 24 | /* Based on code from The OpenGL Programming Guide / 7th Edition, Appendix J. |
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| 25 | * Available here: http://www.opengl-redbook.com/appendices/ |
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| 26 | * The algorithm in the book contains a bug though, which is fixed in the code |
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| 27 | * below. |
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| 28 | */ |
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| 29 | |||
| 30 | #define UF11(e, m) ((e << 6) | (m)) |
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| 31 | #define UF11_EXPONENT_BIAS 15 |
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| 32 | #define UF11_EXPONENT_BITS 0x1F |
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| 33 | #define UF11_EXPONENT_SHIFT 6 |
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| 34 | #define UF11_MANTISSA_BITS 0x3F |
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| 35 | #define UF11_MANTISSA_SHIFT (23 - UF11_EXPONENT_SHIFT) |
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| 36 | #define UF11_MAX_EXPONENT (UF11_EXPONENT_BITS << UF11_EXPONENT_SHIFT) |
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| 37 | |||
| 38 | #define UF10(e, m) ((e << 5) | (m)) |
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| 39 | #define UF10_EXPONENT_BIAS 15 |
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| 40 | #define UF10_EXPONENT_BITS 0x1F |
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| 41 | #define UF10_EXPONENT_SHIFT 5 |
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| 42 | #define UF10_MANTISSA_BITS 0x1F |
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| 43 | #define UF10_MANTISSA_SHIFT (23 - UF10_EXPONENT_SHIFT) |
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| 44 | #define UF10_MAX_EXPONENT (UF10_EXPONENT_BITS << UF10_EXPONENT_SHIFT) |
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| 45 | |||
| 46 | #define F32_INFINITY 0x7f800000 |
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| 47 | |||
| 48 | static INLINE unsigned f32_to_uf11(float val) |
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| 49 | { |
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| 50 | union { |
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| 51 | float f; |
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| 52 | uint32_t ui; |
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| 53 | } f32 = {val}; |
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| 54 | |||
| 55 | uint16_t uf11 = 0; |
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| 56 | |||
| 57 | /* Decode little-endian 32-bit floating-point value */ |
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| 58 | int sign = (f32.ui >> 16) & 0x8000; |
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| 59 | /* Map exponent to the range [-127,128] */ |
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| 60 | int exponent = ((f32.ui >> 23) & 0xff) - 127; |
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| 61 | int mantissa = f32.ui & 0x007fffff; |
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| 62 | |||
| 63 | if (exponent == 128) { /* Infinity or NaN */ |
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| 64 | /* From the GL_EXT_packed_float spec: |
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| 65 | * |
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| 66 | * "Additionally: negative infinity is converted to zero; positive |
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| 67 | * infinity is converted to positive infinity; and both positive and |
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| 68 | * negative NaN are converted to positive NaN." |
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| 69 | */ |
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| 70 | uf11 = UF11_MAX_EXPONENT; |
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| 71 | if (mantissa) { |
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| 72 | uf11 |= 1; /* NaN */ |
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| 73 | } else { |
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| 74 | if (sign) |
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| 75 | uf11 = 0; /* 0.0 */ |
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| 76 | } |
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| 77 | } else if (sign) { |
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| 78 | return 0; |
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| 79 | } else if (val > 65024.0f) { |
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| 80 | /* From the GL_EXT_packed_float spec: |
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| 81 | * |
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| 82 | * "Likewise, finite positive values greater than 65024 (the maximum |
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| 83 | * finite representable unsigned 11-bit floating-point value) are |
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| 84 | * converted to 65024." |
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| 85 | */ |
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| 86 | uf11 = UF11(30, 63); |
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| 87 | } |
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| 88 | else if (exponent > -15) { /* Representable value */ |
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| 89 | exponent += UF11_EXPONENT_BIAS; |
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| 90 | mantissa >>= UF11_MANTISSA_SHIFT; |
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| 91 | uf11 = exponent << UF11_EXPONENT_SHIFT | mantissa; |
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| 92 | } |
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| 93 | |||
| 94 | return uf11; |
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| 95 | } |
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| 96 | |||
| 97 | static INLINE float uf11_to_f32(uint16_t val) |
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| 98 | { |
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| 99 | union { |
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| 100 | float f; |
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| 101 | uint32_t ui; |
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| 102 | } f32; |
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| 103 | |||
| 104 | int exponent = (val & 0x07c0) >> UF11_EXPONENT_SHIFT; |
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| 105 | int mantissa = (val & 0x003f); |
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| 106 | |||
| 107 | f32.f = 0.0; |
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| 108 | |||
| 109 | if (exponent == 0) { |
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| 110 | if (mantissa != 0) { |
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| 111 | const float scale = 1.0 / (1 << 20); |
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| 112 | f32.f = scale * mantissa; |
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| 113 | } |
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| 114 | } |
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| 115 | else if (exponent == 31) { |
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| 116 | f32.ui = F32_INFINITY | mantissa; |
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| 117 | } |
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| 118 | else { |
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| 119 | float scale, decimal; |
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| 120 | exponent -= 15; |
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| 121 | if (exponent < 0) { |
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| 122 | scale = 1.0f / (1 << -exponent); |
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| 123 | } |
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| 124 | else { |
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| 125 | scale = (float) (1 << exponent); |
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| 126 | } |
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| 127 | decimal = 1.0f + (float) mantissa / 64; |
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| 128 | f32.f = scale * decimal; |
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| 129 | } |
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| 130 | |||
| 131 | return f32.f; |
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| 132 | } |
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| 133 | |||
| 134 | static INLINE unsigned f32_to_uf10(float val) |
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| 135 | { |
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| 136 | union { |
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| 137 | float f; |
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| 138 | uint32_t ui; |
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| 139 | } f32 = {val}; |
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| 140 | |||
| 141 | uint16_t uf10 = 0; |
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| 142 | |||
| 143 | /* Decode little-endian 32-bit floating-point value */ |
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| 144 | int sign = (f32.ui >> 16) & 0x8000; |
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| 145 | /* Map exponent to the range [-127,128] */ |
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| 146 | int exponent = ((f32.ui >> 23) & 0xff) - 127; |
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| 147 | int mantissa = f32.ui & 0x007fffff; |
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| 148 | |||
| 149 | if (exponent == 128) { |
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| 150 | /* From the GL_EXT_packed_float spec: |
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| 151 | * |
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| 152 | * "Additionally: negative infinity is converted to zero; positive |
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| 153 | * infinity is converted to positive infinity; and both positive and |
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| 154 | * negative NaN are converted to positive NaN." |
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| 155 | */ |
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| 156 | uf10 = UF10_MAX_EXPONENT; |
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| 157 | if (mantissa) { |
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| 158 | uf10 |= 1; /* NaN */ |
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| 159 | } else { |
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| 160 | if (sign) |
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| 161 | uf10 = 0; /* 0.0 */ |
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| 162 | } |
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| 163 | } else if (sign) { |
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| 164 | return 0; |
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| 165 | } else if (val > 64512.0f) { |
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| 166 | /* From the GL_EXT_packed_float spec: |
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| 167 | * |
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| 168 | * "Likewise, finite positive values greater than 64512 (the maximum |
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| 169 | * finite representable unsigned 10-bit floating-point value) are |
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| 170 | * converted to 64512." |
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| 171 | */ |
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| 172 | uf10 = UF10(30, 31); |
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| 173 | } |
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| 174 | else if (exponent > -15) { /* Representable value */ |
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| 175 | exponent += UF10_EXPONENT_BIAS; |
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| 176 | mantissa >>= UF10_MANTISSA_SHIFT; |
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| 177 | uf10 = exponent << UF10_EXPONENT_SHIFT | mantissa; |
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| 178 | } |
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| 179 | |||
| 180 | return uf10; |
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| 181 | } |
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| 182 | |||
| 183 | static INLINE float uf10_to_f32(uint16_t val) |
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| 184 | { |
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| 185 | union { |
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| 186 | float f; |
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| 187 | uint32_t ui; |
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| 188 | } f32; |
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| 189 | |||
| 190 | int exponent = (val & 0x03e0) >> UF10_EXPONENT_SHIFT; |
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| 191 | int mantissa = (val & 0x001f); |
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| 192 | |||
| 193 | f32.f = 0.0; |
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| 194 | |||
| 195 | if (exponent == 0) { |
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| 196 | if (mantissa != 0) { |
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| 197 | const float scale = 1.0 / (1 << 20); |
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| 198 | f32.f = scale * mantissa; |
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| 199 | } |
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| 200 | } |
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| 201 | else if (exponent == 31) { |
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| 202 | f32.ui = F32_INFINITY | mantissa; |
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| 203 | } |
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| 204 | else { |
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| 205 | float scale, decimal; |
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| 206 | exponent -= 15; |
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| 207 | if (exponent < 0) { |
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| 208 | scale = 1.0f / (1 << -exponent); |
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| 209 | } |
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| 210 | else { |
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| 211 | scale = (float) (1 << exponent); |
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| 212 | } |
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| 213 | decimal = 1.0f + (float) mantissa / 32; |
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| 214 | f32.f = scale * decimal; |
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| 215 | } |
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| 216 | |||
| 217 | return f32.f; |
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| 218 | } |
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| 219 | |||
| 220 | static INLINE unsigned float3_to_r11g11b10f(const float rgb[3]) |
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| 221 | { |
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| 222 | return ( f32_to_uf11(rgb[0]) & 0x7ff) | |
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| 223 | ((f32_to_uf11(rgb[1]) & 0x7ff) << 11) | |
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| 224 | ((f32_to_uf10(rgb[2]) & 0x3ff) << 22); |
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| 225 | } |
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| 226 | |||
| 227 | static INLINE void r11g11b10f_to_float3(unsigned rgb, float retval[3]) |
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| 228 | { |
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| 229 | retval[0] = uf11_to_f32( rgb & 0x7ff); |
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| 230 | retval[1] = uf11_to_f32((rgb >> 11) & 0x7ff); |
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| 231 | retval[2] = uf10_to_f32((rgb >> 22) & 0x3ff); |
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| 232 | } |