| 1 | /* mpz_gcd_ui -- Calculate the greatest common divisior of two integers. |
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| 2 | |
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| 3 | Copyright 1994, 1996, 1999, 2000, 2001, 2002, 2003 Free Software Foundation, |
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| 4 | Inc. |
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| 5 | |
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| 6 | This file is part of the GNU MP Library. |
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| 7 | |
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| 8 | The GNU MP Library is free software; you can redistribute it and/or modify |
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| 9 | it under the terms of the GNU Lesser General Public License as published by |
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| 10 | the Free Software Foundation; either version 2.1 of the License, or (at your |
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| 11 | option) any later version. |
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| 12 | |
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| 13 | The GNU MP Library is distributed in the hope that it will be useful, but |
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| 14 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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| 15 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
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| 16 | License for more details. |
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| 17 | |
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| 18 | You should have received a copy of the GNU Lesser General Public License |
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| 19 | along with the GNU MP Library; see the file COPYING.LIB. If not, write to |
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| 20 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
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| 21 | MA 02111-1307, USA. */ |
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| 22 | |
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| 23 | #include <stdio.h> /* for NULL */ |
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| 24 | #include "gmp.h" |
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| 25 | #include "gmp-impl.h" |
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| 26 | |
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| 27 | unsigned long int |
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| 28 | mpz_gcd_ui (mpz_ptr w, mpz_srcptr u, unsigned long int v) |
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| 29 | { |
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| 30 | mp_size_t un; |
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| 31 | mp_limb_t res; |
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| 32 | |
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| 33 | #if GMP_NAIL_BITS != 0 |
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| 34 | if (v > GMP_NUMB_MAX) |
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| 35 | { |
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| 36 | mpz_t vz; |
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| 37 | mp_limb_t vlimbs[2]; |
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| 38 | vlimbs[0] = v & GMP_NUMB_MASK; |
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| 39 | vlimbs[1] = v >> GMP_NUMB_BITS; |
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| 40 | PTR(vz) = vlimbs; |
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| 41 | SIZ(vz) = 2; |
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| 42 | mpz_gcd (w, u, vz); |
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| 43 | return; |
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| 44 | } |
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| 45 | #endif |
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| 46 | |
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| 47 | un = ABSIZ(u); |
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| 48 | |
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| 49 | if (un == 0) |
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| 50 | res = v; |
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| 51 | else if (v == 0) |
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| 52 | { |
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| 53 | if (w != NULL) |
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| 54 | { |
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| 55 | if (u != w) |
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| 56 | { |
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| 57 | MPZ_REALLOC (w, un); |
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| 58 | MPN_COPY (PTR(w), PTR(u), un); |
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| 59 | } |
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| 60 | SIZ(w) = un; |
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| 61 | } |
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| 62 | /* Return u if it fits a ulong, otherwise 0. */ |
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| 63 | res = PTR(u)[0]; |
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| 64 | return (un == 1 && res <= ULONG_MAX ? res : 0); |
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| 65 | } |
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| 66 | else |
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| 67 | res = mpn_gcd_1 (PTR(u), un, (mp_limb_t) v); |
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| 68 | |
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| 69 | if (w != NULL) |
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| 70 | { |
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| 71 | PTR(w)[0] = res; |
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| 72 | SIZ(w) = res != 0; |
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| 73 | } |
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| 74 | return res; |
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| 75 | } |
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