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
36
37 #include <iostream>
38 #include <iomanip>
39
40 using namespace std;
41
42 //-----------------------------------------------------
43 // Compute a lookup table for float-to-half conversion.
44 //
45 // When indexed with the combined sign and exponent of
46 // a float, the table either returns the combined sign
47 // and exponent of the corresponding half, or zero if
48 // the corresponding half may not be normalized (zero,
49 // denormalized, overflow).
50 //-----------------------------------------------------
51
52 void
initELut(unsigned short eLut[])53 initELut (unsigned short eLut[])
54 {
55 for (int i = 0; i < 0x100; i++)
56 {
57 int e = (i & 0x0ff) - (127 - 15);
58
59 if (e <= 0 || e >= 30)
60 {
61 //
62 // Special case
63 //
64
65 eLut[i] = 0;
66 eLut[i | 0x100] = 0;
67 }
68 else
69 {
70 //
71 // Common case - normalized half, no exponent overflow possible
72 //
73
74 eLut[i] = (e << 10);
75 eLut[i | 0x100] = ((e << 10) | 0x8000);
76 }
77 }
78 }
79
80
81 //------------------------------------------------------------
82 // Main - prints the sign-and-exponent conversion lookup table
83 //------------------------------------------------------------
84
85 int
main()86 main ()
87 {
88 const int tableSize = 1 << 9;
89 unsigned short eLut[tableSize];
90 initELut (eLut);
91
92 cout << "//\n"
93 "// This is an automatically generated file.\n"
94 "// Do not edit.\n"
95 "//\n\n";
96
97 cout << "{\n ";
98
99 for (int i = 0; i < tableSize; i++)
100 {
101 cout << setw (5) << eLut[i] << ", ";
102
103 if (i % 8 == 7)
104 {
105 cout << "\n";
106
107 if (i < tableSize - 1)
108 cout << " ";
109 }
110 }
111
112 cout << "};\n";
113 return 0;
114 }
115