/src/FreeImage/Source/OpenEXR/Half/eLut.cpp

https://bitbucket.org/cabalistic/ogredeps/ · C++ · 114 lines · 45 code · 18 blank · 51 comment · 7 complexity · 982a90d0eba60fd6ab9d771c559b296a MD5 · raw file

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