1 /* 2 * Copyright (C) 2011 Marek Olk <maraeo (at) gmail.com> 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 21 * DEALINGS IN THE SOFTWARE. 22 */ 23 24 /* Copied from EXT_texture_shared_exponent and edited. */ 25 26 #ifndef RGB9E5_H 27 #define RGB9E5_H 28 29 #include <math.h> 30 #include <assert.h> 31 32 #define RGB9E5_EXPONENT_BITS 5 33 #define RGB9E5_MANTISSA_BITS 9 34 #define RGB9E5_EXP_BIAS 15 35 #define RGB9E5_MAX_VALID_BIASED_EXP 31 36 37 #define MAX_RGB9E5_EXP (RGB9E5_MAX_VALID_BIASED_EXP - RGB9E5_EXP_BIAS) 38 #define RGB9E5_MANTISSA_VALUES (1<<RGB9E5_MANTISSA_BITS) 39 #define MAX_RGB9E5_MANTISSA (RGB9E5_MANTISSA_VALUES-1) 40 #define MAX_RGB9E5 (((float)MAX_RGB9E5_MANTISSA)/RGB9E5_MANTISSA_VALUES * (1<<MAX_RGB9E5_EXP)) 41 #define EPSILON_RGB9E5 ((1.0/RGB9E5_MANTISSA_VALUES) / (1<<RGB9E5_EXP_BIAS)) 42 43 typedef union { 44 unsigned int raw; 45 float value; 46 struct { 47 #if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN) 48 unsigned int negative:1; 49 unsigned int biasedexponent:8; 50 unsigned int mantissa:23; 51 #else 52 unsigned int mantissa:23; 53 unsigned int biasedexponent:8; 54 unsigned int negative:1; 55 #endif 56 } field; 57 } float754; 58 59 typedef union { 60 unsigned int raw; 61 struct { 62 #if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN) 63 unsigned int biasedexponent:RGB9E5_EXPONENT_BITS; 64 unsigned int b:RGB9E5_MANTISSA_BITS; 65 unsigned int g:RGB9E5_MANTISSA_BITS; 66 unsigned int r:RGB9E5_MANTISSA_BITS; 67 #else 68 unsigned int r:RGB9E5_MANTISSA_BITS; 69 unsigned int g:RGB9E5_MANTISSA_BITS; 70 unsigned int b:RGB9E5_MANTISSA_BITS; 71 unsigned int biasedexponent:RGB9E5_EXPONENT_BITS; 72 #endif 73 } field; 74 } rgb9e5; 75 76 static INLINE float rgb9e5_ClampRange(float x) 77 { 78 if (x > 0.0) { 79 if (x >= MAX_RGB9E5) { 80 return MAX_RGB9E5; 81 } else { 82 return x; 83 } 84 } else { 85 /* NaN gets here too since comparisons with NaN always fail! */ 86 return 0.0; 87 } 88 } 89 90 /* Ok, FloorLog2 is not correct for the denorm and zero values, but we 91 are going to do a max of this value with the minimum rgb9e5 exponent 92 that will hide these problem cases. */ 93 static INLINE int rgb9e5_FloorLog2(float x) 94 { 95 float754 f; 96 97 f.value = x; 98 return (f.field.biasedexponent - 127); 99 } 100 101 static INLINE unsigned float3_to_rgb9e5(const float rgb[3]) 102 { 103 rgb9e5 retval; 104 float maxrgb; 105 int rm, gm, bm; 106 float rc, gc, bc; 107 int exp_shared, maxm; 108 double denom; 109 110 rc = rgb9e5_ClampRange(rgb[0]); 111 gc = rgb9e5_ClampRange(rgb[1]); 112 bc = rgb9e5_ClampRange(rgb[2]); 113 114 maxrgb = MAX3(rc, gc, bc); 115 exp_shared = MAX2(-RGB9E5_EXP_BIAS-1, rgb9e5_FloorLog2(maxrgb)) + 1 + RGB9E5_EXP_BIAS; 116 assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP); 117 assert(exp_shared >= 0); 118 /* This pow function could be replaced by a table. */ 119 denom = pow(2, exp_shared - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS); 120 121 maxm = (int) floor(maxrgb / denom + 0.5); 122 if (maxm == MAX_RGB9E5_MANTISSA+1) { 123 denom *= 2; 124 exp_shared += 1; 125 assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP); 126 } else { 127 assert(maxm <= MAX_RGB9E5_MANTISSA); 128 } 129 130 rm = (int) floor(rc / denom + 0.5); 131 gm = (int) floor(gc / denom + 0.5); 132 bm = (int) floor(bc / denom + 0.5); 133 134 assert(rm <= MAX_RGB9E5_MANTISSA); 135 assert(gm <= MAX_RGB9E5_MANTISSA); 136 assert(bm <= MAX_RGB9E5_MANTISSA); 137 assert(rm >= 0); 138 assert(gm >= 0); 139 assert(bm >= 0); 140 141 retval.field.r = rm; 142 retval.field.g = gm; 143 retval.field.b = bm; 144 retval.field.biasedexponent = exp_shared; 145 146 return retval.raw; 147 } 148 149 static INLINE void rgb9e5_to_float3(unsigned rgb, float retval[3]) 150 { 151 rgb9e5 v; 152 int exponent; 153 float scale; 154 155 v.raw = rgb; 156 exponent = v.field.biasedexponent - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS; 157 scale = (float) pow(2, exponent); 158 159 retval[0] = v.field.r * scale; 160 retval[1] = v.field.g * scale; 161 retval[2] = v.field.b * scale; 162 } 163 164 #endif 165
