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source:
trunk/third/gmp/mpz/tdiv_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_tdiv_r_ui(rem, dividend, divisor_limb) |

2 | -- Set REM to DIVDEND mod DIVISOR_LIMB. |

3 | |

4 | Copyright 1991, 1993, 1994, 1996, 1998, 2001, 2002 Free Software Foundation, |

5 | Inc. |

6 | |

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

8 | |

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

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

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

12 | option) any later version. |

13 | |

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

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

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

17 | License for more details. |

18 | |

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

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

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

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

23 | |

24 | #include "gmp.h" |

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

26 | |

27 | unsigned long int |

28 | mpz_tdiv_r_ui (mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor) |

29 | { |

30 | mp_size_t ns, nn; |

31 | mp_ptr np; |

32 | mp_limb_t rl; |

33 | |

34 | if (divisor == 0) |

35 | DIVIDE_BY_ZERO; |

36 | |

37 | ns = SIZ(dividend); |

38 | if (ns == 0) |

39 | { |

40 | SIZ(rem) = 0; |

41 | return 0; |

42 | } |

43 | |

44 | nn = ABS(ns); |

45 | np = PTR(dividend); |

46 | #if GMP_NAIL_BITS != 0 |

47 | if (divisor > GMP_NUMB_MAX) |

48 | { |

49 | mp_limb_t dp[2]; |

50 | mp_ptr rp, qp; |

51 | mp_size_t rn; |

52 | TMP_DECL (mark); |

53 | |

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

55 | { |

56 | rl = np[0]; |

57 | SIZ(rem) = ns >= 0 ? 1 : -1; |

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

59 | return rl; |

60 | } |

61 | |

62 | MPZ_REALLOC (rem, 2); |

63 | rp = PTR(rem); |

64 | |

65 | TMP_MARK (mark); |

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

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

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

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

70 | TMP_FREE (mark); |

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

72 | rn = 2 - (rp[1] == 0); rn -= (rp[rn - 1] == 0); |

73 | SIZ(rem) = ns >= 0 ? rn : -rn; |

74 | } |

75 | else |

76 | #endif |

77 | { |

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

79 | if (rl == 0) |

80 | SIZ(rem) = 0; |

81 | else |

82 | { |

83 | /* Store the single-limb remainder. We don't check if there's space |

84 | for just one limb, since no function ever makes zero space. */ |

85 | SIZ(rem) = ns >= 0 ? 1 : -1; |

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

87 | } |

88 | } |

89 | |

90 | return rl; |

91 | } |

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