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source:
trunk/third/gmp/mpz/tdiv_qr_ui.c
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18191

Revision 18191, 2.5 KB checked in by ghudson, 22 years ago (diff) |
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1 | /* mpz_tdiv_qr_ui(quot,rem,dividend,short_divisor) -- |

2 | Set QUOT to DIVIDEND / SHORT_DIVISOR |

3 | and REM to DIVIDEND mod SHORT_DIVISOR. |

4 | |

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

6 | Inc. |

7 | |

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

9 | |

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

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

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

13 | option) any later version. |

14 | |

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

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

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

18 | License for more details. |

19 | |

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

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

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

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

24 | |

25 | #include "gmp.h" |

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

27 | |

28 | unsigned long int |

29 | mpz_tdiv_qr_ui (mpz_ptr quot, mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor) |

30 | { |

31 | mp_size_t ns, nn, qn; |

32 | mp_ptr np, qp; |

33 | mp_limb_t rl; |

34 | |

35 | if (divisor == 0) |

36 | DIVIDE_BY_ZERO; |

37 | |

38 | ns = SIZ(dividend); |

39 | if (ns == 0) |

40 | { |

41 | SIZ(quot) = 0; |

42 | SIZ(rem) = 0; |

43 | return 0; |

44 | } |

45 | |

46 | nn = ABS(ns); |

47 | MPZ_REALLOC (quot, nn); |

48 | qp = PTR(quot); |

49 | np = PTR(dividend); |

50 | |

51 | #if GMP_NAIL_BITS != 0 |

52 | if (divisor > GMP_NUMB_MAX) |

53 | { |

54 | mp_limb_t dp[2]; |

55 | mp_ptr rp; |

56 | mp_size_t rn; |

57 | |

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

59 | { |

60 | SIZ(quot) = 0; |

61 | rl = np[0]; |

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

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

64 | return rl; |

65 | } |

66 | |

67 | MPZ_REALLOC (rem, 2); |

68 | rp = PTR(rem); |

69 | |

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

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

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

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

74 | qn = nn - 2 + 1; qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0; |

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

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

77 | } |

78 | else |

79 | #endif |

80 | { |

81 | rl = mpn_divrem_1 (qp, (mp_size_t) 0, np, nn, (mp_limb_t) divisor); |

82 | if (rl == 0) |

83 | SIZ(rem) = 0; |

84 | else |

85 | { |

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

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

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

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

90 | } |

91 | qn = nn - (qp[nn - 1] == 0); |

92 | } |

93 | |

94 | SIZ(quot) = ns >= 0 ? qn : -qn; |

95 | return rl; |

96 | } |

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