/js/lib/Socket.IO-node/support/expresso/deps/jscoverage/js/jslog2.cpp

http://github.com/onedayitwillmake/RealtimeMultiplayerNodeJs · C++ · 94 lines · 36 code · 11 blank · 47 comment · 13 complexity · 7d9741b11f97c6ef5cf1caeab2bdd399 MD5 · raw file

  1. /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
  2. /* ***** BEGIN LICENSE BLOCK *****
  3. * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4. *
  5. * The contents of this file are subject to the Mozilla Public License Version
  6. * 1.1 (the "License"); you may not use this file except in compliance with
  7. * the License. You may obtain a copy of the License at
  8. * http://www.mozilla.org/MPL/
  9. *
  10. * Software distributed under the License is distributed on an "AS IS" basis,
  11. * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12. * for the specific language governing rights and limitations under the
  13. * License.
  14. *
  15. * The Original Code is Mozilla Communicator client code, released
  16. * March 31, 1998.
  17. *
  18. * The Initial Developer of the Original Code is
  19. * Netscape Communications Corporation.
  20. * Portions created by the Initial Developer are Copyright (C) 1998
  21. * the Initial Developer. All Rights Reserved.
  22. *
  23. * Contributor(s):
  24. *
  25. * Alternatively, the contents of this file may be used under the terms of
  26. * either of the GNU General Public License Version 2 or later (the "GPL"),
  27. * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28. * in which case the provisions of the GPL or the LGPL are applicable instead
  29. * of those above. If you wish to allow use of your version of this file only
  30. * under the terms of either the GPL or the LGPL, and not to allow others to
  31. * use your version of this file under the terms of the MPL, indicate your
  32. * decision by deleting the provisions above and replace them with the notice
  33. * and other provisions required by the GPL or the LGPL. If you do not delete
  34. * the provisions above, a recipient may use your version of this file under
  35. * the terms of any one of the MPL, the GPL or the LGPL.
  36. *
  37. * ***** END LICENSE BLOCK ***** */
  38. #include "jsstddef.h"
  39. #include "jsbit.h"
  40. #include "jsutil.h"
  41. /*
  42. ** Compute the log of the least power of 2 greater than or equal to n
  43. */
  44. JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 n)
  45. {
  46. JSIntn log2;
  47. JS_CEILING_LOG2(log2, n);
  48. return log2;
  49. }
  50. /*
  51. ** Compute the log of the greatest power of 2 less than or equal to n.
  52. ** This really just finds the highest set bit in the word.
  53. */
  54. JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 n)
  55. {
  56. JSIntn log2;
  57. JS_FLOOR_LOG2(log2, n);
  58. return log2;
  59. }
  60. /*
  61. * js_FloorLog2wImpl has to be defined only for 64-bit non-GCC case.
  62. */
  63. #if !defined(JS_HAS_BUILTIN_BITSCAN64) && JS_BYTES_PER_WORD == 8
  64. JSUword
  65. js_FloorLog2wImpl(JSUword n)
  66. {
  67. JSUword log2, m;
  68. JS_ASSERT(n != 0);
  69. log2 = 0;
  70. m = n >> 32;
  71. if (m != 0) { n = m; log2 = 32; }
  72. m = n >> 16;
  73. if (m != 0) { n = m; log2 |= 16; }
  74. m = n >> 8;
  75. if (m != 0) { n = m; log2 |= 8; }
  76. m = n >> 4;
  77. if (m != 0) { n = m; log2 |= 4; }
  78. m = n >> 2;
  79. if (m != 0) { n = m; log2 |= 2; }
  80. log2 |= (n >> 1);
  81. return log2;
  82. }
  83. #endif