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  1. // Emacs style mode select   -*- C++ -*-
  2. //-----------------------------------------------------------------------------
  3. //
  4. // $Id:$
  5. //
  6. // Copyright (C) 1993-1996 by id Software, Inc.
  7. //
  8. // This source is available for distribution and/or modification
  9. // only under the terms of the DOOM Source Code License as
  10. // published by id Software. All rights reserved.
  11. //
  12. // The source is distributed in the hope that it will be useful,
  13. // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14. // FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
  15. // for more details.
  16. //
  17. // $Log:$
  18. //
  19. // DESCRIPTION:
  20. //      Fixed point implementation.
  21. //
  22. //-----------------------------------------------------------------------------
  23.  
  24.  
  25. static const char
  26. rcsid[] = "$Id: m_bbox.c,v 1.1 1997/02/03 22:45:10 b1 Exp $";
  27.  
  28. #include "stdlib.h"
  29.  
  30. #include "doomtype.h"
  31. #include "i_system.h"
  32.  
  33. #ifdef __GNUG__
  34. #pragma implementation "m_fixed.h"
  35. #endif
  36. #include "m_fixed.h"
  37.  
  38.  
  39.  
  40.  
  41. // Fixme. __USE_C_FIXED__ or something.
  42.  
  43. fixed_t
  44. FixedMul
  45. ( fixed_t       a,
  46.   fixed_t       b )
  47. {
  48.     return ((long long) a * (long long) b) >> FRACBITS;
  49. }
  50.  
  51.  
  52.  
  53. //
  54. // FixedDiv, C version.
  55. //
  56.  
  57. fixed_t
  58. FixedDiv
  59. ( fixed_t       a,
  60.   fixed_t       b )
  61. {
  62.     if ( (abs(a)>>14) >= abs(b))
  63.         return (a^b)<0 ? MININT : MAXINT;
  64.     return FixedDiv2 (a,b);
  65. }
  66.  
  67.  
  68.  
  69. fixed_t
  70. FixedDiv2
  71. ( fixed_t       a,
  72.   fixed_t       b )
  73. {
  74. #if 0
  75.     long long c;
  76.     c = ((long long)a<<16) / ((long long)b);
  77.     return (fixed_t) c;
  78. #endif
  79.  
  80.     double c;
  81.  
  82.     c = ((double)a) / ((double)b) * FRACUNIT;
  83.  
  84.     if (c >= 2147483648.0 || c < -2147483648.0)
  85.         I_Error("FixedDiv: divide by zero");
  86.     return (fixed_t) c;
  87. }
  88.