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