half_float.h
1 /*
2 ** ClanLib SDK
3 ** Copyright (c) 1997-2016 The ClanLib Team
4 **
5 ** This software is provided 'as-is', without any express or implied
6 ** warranty. In no event will the authors be held liable for any damages
7 ** arising from the use of this software.
8 **
9 ** Permission is granted to anyone to use this software for any purpose,
10 ** including commercial applications, and to alter it and redistribute it
11 ** freely, subject to the following restrictions:
12 **
13 ** 1. The origin of this software must not be misrepresented; you must not
14 ** claim that you wrote the original software. If you use this software
15 ** in a product, an acknowledgment in the product documentation would be
16 ** appreciated but is not required.
17 ** 2. Altered source versions must be plainly marked as such, and must not be
18 ** misrepresented as being the original software.
19 ** 3. This notice may not be removed or altered from any source distribution.
20 **
21 ** Note: Some of the libraries ClanLib may link to may have additional
22 ** requirements or restrictions.
23 **
24 ** File Author(s):
25 **
26 ** Magnus Norddahl
27 */
28 
29 #pragma once
30 
31 namespace clan
32 {
35 
36  class HalfFloat
37  {
38  public:
39  HalfFloat() : value(0)
40  {
41  }
42 
43  HalfFloat(const HalfFloat &other) : value(other.value)
44  {
45  }
46 
47  HalfFloat(float v) : value(float_to_half(v))
48  {
49  }
50 
52  {
53  value = other.value;
54  return *this;
55  }
56 
57  HalfFloat &operator =(const float v)
58  {
59  return from_float(v);
60  }
61 
62  operator float() const
63  {
64  return to_float();
65  }
66 
67  float to_float() const
68  {
69  return half_to_float(value);
70  }
71 
73  {
74  value = float_to_half(v);
75  return *this;
76  }
77 
79  static float half_to_float_simple(unsigned short hf)
80  {
81  unsigned int float_value = ((hf & 0x8000) << 16) | (((hf & 0x7c00) + 0x1C000) << 13) | ((hf & 0x03FF) << 13);
82  void *ptr = static_cast<void*>(&float_value);
83  return *static_cast<float*>(ptr);
84  }
85 
87  static unsigned short float_to_half_simple(float float_value)
88  {
89  void *ptr = static_cast<void*>(&float_value);
90  unsigned int f = *static_cast<unsigned int*>(ptr);
91  return ((f >> 16) & 0x8000) | ((((f & 0x7f800000) - 0x38000000) >> 13) & 0x7c00) | ((f >> 13) & 0x03ff);
92  }
93 
94  static float half_to_float(unsigned short hf)
95  {
96  unsigned int float_value = mantissa_table[offset_table[hf >> 10] + (hf & 0x3ff)] + exponent_table[hf >> 10];
97  void *ptr = static_cast<void*>(&float_value);
98  return *static_cast<float*>(ptr);
99  }
100 
101  static unsigned short float_to_half(float float_value)
102  {
103  void *ptr = static_cast<void*>(&float_value);
104  unsigned int f = *static_cast<unsigned int*>(ptr);
105  return base_table[(f >> 23) & 0x1ff] + ((f & 0x007fffff) >> shift_table[(f >> 23) & 0x1ff]);
106  }
107 
108  private:
109  unsigned short value;
110 
111  static unsigned int mantissa_table[2048];
112  static unsigned int exponent_table[64];
113  static unsigned short offset_table[64];
114 
115  static unsigned short base_table[512];
116  static unsigned char shift_table[512];
117  };
118 
120 }
Definition: clanapp.h:35
HalfFloat(float v)
Definition: half_float.h:47
HalfFloat & from_float(float v)
Definition: half_float.h:72
HalfFloat()
Definition: half_float.h:39
static unsigned short float_to_half_simple(float float_value)
Only works for 'normal' half-float values.
Definition: half_float.h:87
static float half_to_float(unsigned short hf)
Definition: half_float.h:94
float to_float() const
Definition: half_float.h:67
static unsigned short float_to_half(float float_value)
Definition: half_float.h:101
HalfFloat(const HalfFloat &other)
Definition: half_float.h:43
HalfFloat & operator=(const HalfFloat &other)
Definition: half_float.h:51
static float half_to_float_simple(unsigned short hf)
Only works for 'normal' half-float values.
Definition: half_float.h:79
Definition: half_float.h:36