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source:
trunk/third/gmp/mpf/cmp.c
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18191

Revision 18191, 2.4 KB checked in by ghudson, 22 years ago (diff) |
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1 | /* mpf_cmp -- Compare two floats. |

2 | |

3 | Copyright 1993, 1994, 1996, 2001 Free Software Foundation, Inc. |

4 | |

5 | This file is part of the GNU MP Library. |

6 | |

7 | The GNU MP Library is free software; you can redistribute it and/or modify |

8 | it under the terms of the GNU Lesser General Public License as published by |

9 | the Free Software Foundation; either version 2.1 of the License, or (at your |

10 | option) any later version. |

11 | |

12 | The GNU MP Library is distributed in the hope that it will be useful, but |

13 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |

14 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |

15 | License for more details. |

16 | |

17 | You should have received a copy of the GNU Lesser General Public License |

18 | along with the GNU MP Library; see the file COPYING.LIB. If not, write to |

19 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |

20 | MA 02111-1307, USA. */ |

21 | |

22 | #include "gmp.h" |

23 | #include "gmp-impl.h" |

24 | |

25 | int |

26 | mpf_cmp (mpf_srcptr u, mpf_srcptr v) |

27 | { |

28 | mp_srcptr up, vp; |

29 | mp_size_t usize, vsize; |

30 | mp_exp_t uexp, vexp; |

31 | int cmp; |

32 | int usign; |

33 | |

34 | uexp = u->_mp_exp; |

35 | vexp = v->_mp_exp; |

36 | |

37 | usize = u->_mp_size; |

38 | vsize = v->_mp_size; |

39 | |

40 | /* 1. Are the signs different? */ |

41 | if ((usize ^ vsize) >= 0) |

42 | { |

43 | /* U and V are both non-negative or both negative. */ |

44 | if (usize == 0) |

45 | /* vsize >= 0 */ |

46 | return -(vsize != 0); |

47 | if (vsize == 0) |

48 | /* usize >= 0 */ |

49 | return usize != 0; |

50 | /* Fall out. */ |

51 | } |

52 | else |

53 | { |

54 | /* Either U or V is negative, but not both. */ |

55 | return usize >= 0 ? 1 : -1; |

56 | } |

57 | |

58 | /* U and V have the same sign and are both non-zero. */ |

59 | |

60 | usign = usize >= 0 ? 1 : -1; |

61 | |

62 | /* 2. Are the exponents different? */ |

63 | if (uexp > vexp) |

64 | return usign; |

65 | if (uexp < vexp) |

66 | return -usign; |

67 | |

68 | usize = ABS (usize); |

69 | vsize = ABS (vsize); |

70 | |

71 | up = u->_mp_d; |

72 | vp = v->_mp_d; |

73 | |

74 | #define STRICT_MPF_NORMALIZATION 0 |

75 | #if ! STRICT_MPF_NORMALIZATION |

76 | /* Ignore zeroes at the low end of U and V. */ |

77 | while (up[0] == 0) |

78 | { |

79 | up++; |

80 | usize--; |

81 | } |

82 | while (vp[0] == 0) |

83 | { |

84 | vp++; |

85 | vsize--; |

86 | } |

87 | #endif |

88 | |

89 | if (usize > vsize) |

90 | { |

91 | cmp = mpn_cmp (up + usize - vsize, vp, vsize); |

92 | if (cmp == 0) |

93 | return usign; |

94 | } |

95 | else if (vsize > usize) |

96 | { |

97 | cmp = mpn_cmp (up, vp + vsize - usize, usize); |

98 | if (cmp == 0) |

99 | return -usign; |

100 | } |

101 | else |

102 | { |

103 | cmp = mpn_cmp (up, vp, usize); |

104 | if (cmp == 0) |

105 | return 0; |

106 | } |

107 | return cmp > 0 ? usign : -usign; |

108 | } |

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