2 * Copyright (C) 2011 Marek Olšák <maraeo@gmail.com>
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:
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
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.
24 /* Copied from EXT_texture_shared_exponent and edited. */
33 #define RGB9E5_EXPONENT_BITS 5
34 #define RGB9E5_MANTISSA_BITS 9
35 #define RGB9E5_EXP_BIAS 15
36 #define RGB9E5_MAX_VALID_BIASED_EXP 31
38 #define MAX_RGB9E5_EXP (RGB9E5_MAX_VALID_BIASED_EXP - RGB9E5_EXP_BIAS)
39 #define RGB9E5_MANTISSA_VALUES (1<<RGB9E5_MANTISSA_BITS)
40 #define MAX_RGB9E5_MANTISSA (RGB9E5_MANTISSA_VALUES-1)
41 #define MAX_RGB9E5 (((float)MAX_RGB9E5_MANTISSA)/RGB9E5_MANTISSA_VALUES * (1<<MAX_RGB9E5_EXP))
42 #define EPSILON_RGB9E5 ((1.0/RGB9E5_MANTISSA_VALUES) / (1<<RGB9E5_EXP_BIAS))
48 #if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN)
49 unsigned int negative:1;
50 unsigned int biasedexponent:8;
51 unsigned int mantissa:23;
53 unsigned int mantissa:23;
54 unsigned int biasedexponent:8;
55 unsigned int negative:1;
63 #if defined(MESA_BIG_ENDIAN) || defined(PIPE_ARCH_BIG_ENDIAN)
64 unsigned int biasedexponent:RGB9E5_EXPONENT_BITS;
65 unsigned int b:RGB9E5_MANTISSA_BITS;
66 unsigned int g:RGB9E5_MANTISSA_BITS;
67 unsigned int r:RGB9E5_MANTISSA_BITS;
69 unsigned int r:RGB9E5_MANTISSA_BITS;
70 unsigned int g:RGB9E5_MANTISSA_BITS;
71 unsigned int b:RGB9E5_MANTISSA_BITS;
72 unsigned int biasedexponent:RGB9E5_EXPONENT_BITS;
77 static inline float rgb9e5_ClampRange(float x)
80 if (x >= MAX_RGB9E5) {
86 /* NaN gets here too since comparisons with NaN always fail! */
91 /* Ok, FloorLog2 is not correct for the denorm and zero values, but we
92 are going to do a max of this value with the minimum rgb9e5 exponent
93 that will hide these problem cases. */
94 static inline int rgb9e5_FloorLog2(float x)
99 return (f.field.biasedexponent - 127);
102 static inline unsigned float3_to_rgb9e5(const float rgb[3])
108 int exp_shared, maxm;
111 rc = rgb9e5_ClampRange(rgb[0]);
112 gc = rgb9e5_ClampRange(rgb[1]);
113 bc = rgb9e5_ClampRange(rgb[2]);
115 maxrgb = MAX3(rc, gc, bc);
116 exp_shared = MAX2(-RGB9E5_EXP_BIAS-1, rgb9e5_FloorLog2(maxrgb)) + 1 + RGB9E5_EXP_BIAS;
117 assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP);
118 assert(exp_shared >= 0);
119 /* This exp2 function could be replaced by a table. */
120 denom = exp2(exp_shared - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS);
122 maxm = (int) floor(maxrgb / denom + 0.5);
123 if (maxm == MAX_RGB9E5_MANTISSA+1) {
126 assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP);
128 assert(maxm <= MAX_RGB9E5_MANTISSA);
131 rm = (int) floor(rc / denom + 0.5);
132 gm = (int) floor(gc / denom + 0.5);
133 bm = (int) floor(bc / denom + 0.5);
135 assert(rm <= MAX_RGB9E5_MANTISSA);
136 assert(gm <= MAX_RGB9E5_MANTISSA);
137 assert(bm <= MAX_RGB9E5_MANTISSA);
145 retval.field.biasedexponent = exp_shared;
150 static inline void rgb9e5_to_float3(unsigned rgb, float retval[3])
157 exponent = v.field.biasedexponent - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS;
158 scale = exp2f(exponent);
160 retval[0] = v.field.r * scale;
161 retval[1] = v.field.g * scale;
162 retval[2] = v.field.b * scale;