1 ///////////////////////////////////////////////////////////////////////////
2 //
3 // Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
4 // Digital Ltd. LLC
5 //
6 // All rights reserved.
7 //
8 // Redistribution and use in source and binary forms, with or without
9 // modification, are permitted provided that the following conditions are
10 // met:
11 // * Redistributions of source code must retain the above copyright
12 // notice, this list of conditions and the following disclaimer.
13 // * Redistributions in binary form must reproduce the above
14 // copyright notice, this list of conditions and the following disclaimer
15 // in the documentation and/or other materials provided with the
16 // distribution.
17 // * Neither the name of Industrial Light & Magic nor the names of
18 // its contributors may be used to endorse or promote products derived
19 // from this software without specific prior written permission.
20 //
21 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
24 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
25 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
31 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 //
33 ///////////////////////////////////////////////////////////////////////////
34
35 // Primary authors:
36 // Florian Kainz <kainz@ilm.com>
37 // Rod Bogart <rgb@ilm.com>
38
39
40 //---------------------------------------------------------------------------
41 //
42 // halfFunction<T> -- a class for fast evaluation
43 // of half --> T functions
44 //
45 // The constructor for a halfFunction object,
46 //
47 // halfFunction (function,
48 // domainMin, domainMax,
49 // defaultValue,
50 // posInfValue, negInfValue,
51 // nanValue);
52 //
53 // evaluates the function for all finite half values in the interval
54 // [domainMin, domainMax], and stores the results in a lookup table.
55 // For finite half values that are not in [domainMin, domainMax], the
56 // constructor stores defaultValue in the table. For positive infinity,
57 // negative infinity and NANs, posInfValue, negInfValue and nanValue
58 // are stored in the table.
59 //
60 // The tabulated function can then be evaluated quickly for arbitrary
61 // half values by calling the the halfFunction object's operator()
62 // method.
63 //
64 // Example:
65 //
66 // #include <math.h>
67 // #include <halfFunction.h>
68 //
69 // halfFunction<half> hsin (sin);
70 //
71 // halfFunction<half> hsqrt (sqrt, // function
72 // 0, HALF_MAX, // domain
73 // half::qNan(), // sqrt(x) for x < 0
74 // half::posInf(), // sqrt(+inf)
75 // half::qNan(), // sqrt(-inf)
76 // half::qNan()); // sqrt(nan)
77 //
78 // half x = hsin (1);
79 // half y = hsqrt (3.5);
80 //
81 //---------------------------------------------------------------------------
82
83 #ifndef _HALF_FUNCTION_H_
84 #define _HALF_FUNCTION_H_
85
86 #include "half.h"
87
88 #include "IlmBaseConfig.h"
89 #ifndef ILMBASE_HAVE_LARGE_STACK
90 #include <string.h> // need this for memset
91 #else
92 #endif
93
94 #include <float.h>
95
96
97 template <class T>
98 class halfFunction
99 {
100 public:
101
102 //------------
103 // Constructor
104 //------------
105
106 template <class Function>
107 halfFunction (Function f,
108 half domainMin = -HALF_MAX,
109 half domainMax = HALF_MAX,
110 T defaultValue = 0,
111 T posInfValue = 0,
112 T negInfValue = 0,
113 T nanValue = 0);
114
115 #ifndef ILMBASE_HAVE_LARGE_STACK
~halfFunction()116 ~halfFunction () { delete [] _lut; }
117 #endif
118
119 //-----------
120 // Evaluation
121 //-----------
122
123 T operator () (half x) const;
124
125 private:
126
127 #ifdef ILMBASE_HAVE_LARGE_STACK
128 T _lut[1 << 16];
129 #else
130 T * _lut;
131 #endif
132 };
133
134
135 //---------------
136 // Implementation
137 //---------------
138
139 template <class T>
140 template <class Function>
halfFunction(Function f,half domainMin,half domainMax,T defaultValue,T posInfValue,T negInfValue,T nanValue)141 halfFunction<T>::halfFunction (Function f,
142 half domainMin,
143 half domainMax,
144 T defaultValue,
145 T posInfValue,
146 T negInfValue,
147 T nanValue)
148 {
149 #ifndef ILMBASE_HAVE_LARGE_STACK
150 _lut = new T[1<<16];
151 memset (_lut, 0 , (1<<16) * sizeof(T));
152 #endif
153
154 for (int i = 0; i < (1 << 16); i++)
155 {
156 half x;
157 x.setBits (i);
158
159 if (x.isNan())
160 _lut[i] = nanValue;
161 else if (x.isInfinity())
162 _lut[i] = x.isNegative()? negInfValue: posInfValue;
163 else if (x < domainMin || x > domainMax)
164 _lut[i] = defaultValue;
165 else
166 _lut[i] = f (x);
167 }
168 }
169
170
171 template <class T>
172 inline T
operator()173 halfFunction<T>::operator () (half x) const
174 {
175 return _lut[x.bits()];
176 }
177
178
179 #endif
180