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source:
trunk/third/gmp/mpz/fdiv_r_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 | /* mpz_fdiv_r_ui -- Division rounding the quotient towards -infinity. |

2 | The remainder gets the same sign as the denominator. |

3 | |

4 | Copyright 1994, 1995, 1996, 2001, 2002 Free Software Foundation, Inc. |

5 | |

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

7 | |

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

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

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

11 | option) any later version. |

12 | |

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

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

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

16 | License for more details. |

17 | |

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

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

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

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

22 | |

23 | #include "gmp.h" |

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

25 | |

26 | unsigned long int |

27 | mpz_fdiv_r_ui (mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor) |

28 | { |

29 | mp_size_t ns, nn; |

30 | mp_ptr np; |

31 | mp_limb_t rl; |

32 | |

33 | if (divisor == 0) |

34 | DIVIDE_BY_ZERO; |

35 | |

36 | ns = SIZ(dividend); |

37 | if (ns == 0) |

38 | { |

39 | SIZ(rem) = 0; |

40 | return 0; |

41 | } |

42 | |

43 | nn = ABS(ns); |

44 | np = PTR(dividend); |

45 | #if GMP_NAIL_BITS != 0 |

46 | if (divisor > GMP_NUMB_MAX) |

47 | { |

48 | mp_limb_t dp[2]; |

49 | mp_ptr rp, qp; |

50 | mp_size_t rn; |

51 | TMP_DECL (mark); |

52 | |

53 | MPZ_REALLOC (rem, 2); |

54 | rp = PTR(rem); |

55 | |

56 | if (nn == 1) /* tdiv_qr requirements; tested above for 0 */ |

57 | { |

58 | rl = np[0]; |

59 | rp[0] = rl; |

60 | } |

61 | else |

62 | { |

63 | TMP_MARK (mark); |

64 | dp[0] = divisor & GMP_NUMB_MASK; |

65 | dp[1] = divisor >> GMP_NUMB_BITS; |

66 | qp = TMP_ALLOC_LIMBS (nn - 2 + 1); |

67 | mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2); |

68 | TMP_FREE (mark); |

69 | rl = rp[0] + (rp[1] << GMP_NUMB_BITS); |

70 | } |

71 | |

72 | if (rl != 0 && ns < 0) |

73 | { |

74 | rl = divisor - rl; |

75 | rp[0] = rl & GMP_NUMB_MASK; |

76 | rp[1] = rl >> GMP_NUMB_BITS; |

77 | } |

78 | |

79 | rn = 1 + (rl > GMP_NUMB_MAX); rn -= (rp[rn - 1] == 0); |

80 | SIZ(rem) = rn; |

81 | } |

82 | else |

83 | #endif |

84 | { |

85 | rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor); |

86 | if (rl == 0) |

87 | SIZ(rem) = 0; |

88 | else |

89 | { |

90 | if (ns < 0) |

91 | rl = divisor - rl; |

92 | |

93 | PTR(rem)[0] = rl; |

94 | SIZ(rem) = 1; |

95 | } |

96 | } |

97 | |

98 | return rl; |

99 | } |

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