ui_sub.c revision 1.1
1 1.1 mrg /* mpz_ui_sub -- Subtract an unsigned one-word integer and an mpz_t. 2 1.1 mrg 3 1.1 mrg Copyright 2002, 2004 Free Software Foundation, Inc. 4 1.1 mrg 5 1.1 mrg This file is part of the GNU MP Library. 6 1.1 mrg 7 1.1 mrg The GNU MP Library is free software; you can redistribute it and/or modify 8 1.1 mrg it under the terms of the GNU Lesser General Public License as published by 9 1.1 mrg the Free Software Foundation; either version 3 of the License, or (at your 10 1.1 mrg option) any later version. 11 1.1 mrg 12 1.1 mrg The GNU MP Library is distributed in the hope that it will be useful, but 13 1.1 mrg WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 14 1.1 mrg or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 15 1.1 mrg License for more details. 16 1.1 mrg 17 1.1 mrg You should have received a copy of the GNU Lesser General Public License 18 1.1 mrg along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 19 1.1 mrg 20 1.1 mrg #include "gmp.h" 21 1.1 mrg #include "gmp-impl.h" 22 1.1 mrg 23 1.1 mrg void 24 1.1 mrg mpz_ui_sub (mpz_ptr w, unsigned long int uval, mpz_srcptr v) 25 1.1 mrg { 26 1.1 mrg mp_ptr vp, wp; 27 1.1 mrg mp_size_t vn, wn; 28 1.1 mrg mp_limb_t cy; 29 1.1 mrg 30 1.1 mrg #if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */ 31 1.1 mrg if (uval > GMP_NUMB_MAX) 32 1.1 mrg { 33 1.1 mrg mpz_t u; 34 1.1 mrg mp_limb_t ul[2]; 35 1.1 mrg PTR(u) = ul; 36 1.1 mrg ul[0] = uval & GMP_NUMB_MASK; 37 1.1 mrg ul[1] = uval >> GMP_NUMB_BITS; 38 1.1 mrg SIZ(u) = 2; 39 1.1 mrg mpz_sub (w, u, v); 40 1.1 mrg return; 41 1.1 mrg } 42 1.1 mrg #endif 43 1.1 mrg 44 1.1 mrg vp = PTR(v); 45 1.1 mrg vn = SIZ(v); 46 1.1 mrg 47 1.1 mrg wp = PTR(w); 48 1.1 mrg 49 1.1 mrg if (vn > 1) 50 1.1 mrg { 51 1.1 mrg wp = MPZ_REALLOC (w, vn); 52 1.1 mrg vp = PTR(v); 53 1.1 mrg mpn_sub_1 (wp, vp, vn, (mp_limb_t) uval); 54 1.1 mrg wn = -(vn - (wp[vn - 1] == 0)); 55 1.1 mrg } 56 1.1 mrg else if (vn == 1) 57 1.1 mrg { 58 1.1 mrg if (uval >= vp[0]) 59 1.1 mrg { 60 1.1 mrg wp[0] = uval - vp[0]; 61 1.1 mrg wn = wp[0] != 0; 62 1.1 mrg } 63 1.1 mrg else 64 1.1 mrg { 65 1.1 mrg wp[0] = vp[0] - uval; 66 1.1 mrg wn = -1; 67 1.1 mrg } 68 1.1 mrg } 69 1.1 mrg else if (vn == 0) 70 1.1 mrg { 71 1.1 mrg wp[0] = uval; 72 1.1 mrg wn = uval != 0; 73 1.1 mrg } 74 1.1 mrg else /* (vn < 0) */ 75 1.1 mrg { 76 1.1 mrg vn = -vn; 77 1.1 mrg wp = MPZ_REALLOC (w, vn + 1); 78 1.1 mrg vp = PTR(v); 79 1.1 mrg cy = mpn_add_1 (wp, vp, vn, (mp_limb_t) uval); 80 1.1 mrg wp[vn] = cy; 81 1.1 mrg wn = vn + (cy != 0); 82 1.1 mrg } 83 1.1 mrg 84 1.1 mrg SIZ(w) = wn; 85 1.1 mrg } 86
Indexes created Sat Aug 01 00:24:56 UTC 2026