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

Revision 18191, 2.3 KB checked in by ghudson, 22 years ago (diff) |
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1 | /* mpf_cmp_ui -- Compare a float with an unsigned integer. |

2 | |

3 | Copyright 1993, 1994, 1995, 1999, 2001, 2002 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_ui (mpf_srcptr u, unsigned long int vval) |

27 | { |

28 | mp_srcptr up; |

29 | mp_size_t usize; |

30 | mp_exp_t uexp; |

31 | mp_limb_t ulimb; |

32 | |

33 | uexp = u->_mp_exp; |

34 | usize = u->_mp_size; |

35 | |

36 | /* 1. Is U negative? */ |

37 | if (usize < 0) |

38 | return -1; |

39 | /* We rely on usize being non-negative in the code that follows. */ |

40 | |

41 | if (vval == 0) |

42 | return usize != 0; |

43 | |

44 | /* 2. Are the exponents different (V's exponent == 1)? */ |

45 | #if GMP_NAIL_BITS != 0 |

46 | if (uexp > 1 + (vval > GMP_NUMB_MAX)) |

47 | return 1; |

48 | if (uexp < 1 + (vval > GMP_NUMB_MAX)) |

49 | return -1; |

50 | #else |

51 | if (uexp > 1) |

52 | return 1; |

53 | if (uexp < 1) |

54 | return -1; |

55 | #endif |

56 | |

57 | up = u->_mp_d; |

58 | |

59 | ulimb = up[usize - 1]; |

60 | #if GMP_NAIL_BITS != 0 |

61 | if (usize >= 2 && uexp == 2) |

62 | { |

63 | if ((ulimb >> GMP_NAIL_BITS) != 0) |

64 | return 1; |

65 | ulimb = (ulimb << GMP_NUMB_BITS) | up[usize - 2]; |

66 | usize--; |

67 | } |

68 | #endif |

69 | usize--; |

70 | |

71 | /* 3. Compare the most significant mantissa limb with V. */ |

72 | if (ulimb > vval) |

73 | return 1; |

74 | else if (ulimb < vval) |

75 | return -1; |

76 | |

77 | /* Ignore zeroes at the low end of U. */ |

78 | while (*up == 0) |

79 | { |

80 | up++; |

81 | usize--; |

82 | } |

83 | |

84 | /* 4. Now, if the number of limbs are different, we have a difference |

85 | since we have made sure the trailing limbs are not zero. */ |

86 | if (usize > 0) |

87 | return 1; |

88 | |

89 | /* Wow, we got zero even if we tried hard to avoid it. */ |

90 | return 0; |

91 | } |

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