1 /* mpz_add, mpz_sub -- add or subtract integers. 2 3 Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2011, 2012 Free Software 4 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 either: 10 11 * the GNU Lesser General Public License as published by the Free 12 Software Foundation; either version 3 of the License, or (at your 13 option) any later version. 14 15 or 16 17 * the GNU General Public License as published by the Free Software 18 Foundation; either version 2 of the License, or (at your option) any 19 later version. 20 21 or both in parallel, as here. 22 23 The GNU MP Library is distributed in the hope that it will be useful, but 24 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 25 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 26 for more details. 27 28 You should have received copies of the GNU General Public License and the 29 GNU Lesser General Public License along with the GNU MP Library. If not, 30 see https://www.gnu.org/licenses/. */ 31 32 #include "gmp-impl.h" 33 34 35 #ifdef OPERATION_add 36 #define FUNCTION mpz_add 37 #define VARIATION 38 #endif 39 #ifdef OPERATION_sub 40 #define FUNCTION mpz_sub 41 #define VARIATION - 42 #endif 43 44 #ifndef FUNCTION 45 Error, need OPERATION_add or OPERATION_sub 46 #endif 47 48 49 void 50 FUNCTION (mpz_ptr w, mpz_srcptr u, mpz_srcptr v) 51 { 52 mp_srcptr up, vp; 53 mp_ptr wp; 54 mp_size_t usize, vsize, wsize; 55 mp_size_t abs_usize; 56 mp_size_t abs_vsize; 57 58 usize = SIZ(u); 59 vsize = VARIATION SIZ(v); 60 abs_usize = ABS (usize); 61 abs_vsize = ABS (vsize); 62 63 if (abs_usize < abs_vsize) 64 { 65 /* Swap U and V. */ 66 MPZ_SRCPTR_SWAP (u, v); 67 MP_SIZE_T_SWAP (usize, vsize); 68 MP_SIZE_T_SWAP (abs_usize, abs_vsize); 69 } 70 71 /* True: ABS_USIZE >= ABS_VSIZE. */ 72 73 /* If not space for w (and possible carry), increase space. */ 74 wsize = abs_usize + 1; 75 wp = MPZ_REALLOC (w, wsize); 76 77 /* These must be after realloc (u or v may be the same as w). */ 78 up = PTR(u); 79 vp = PTR(v); 80 81 if ((usize ^ vsize) < 0) 82 { 83 /* U and V have different sign. Need to compare them to determine 84 which operand to subtract from which. */ 85 86 /* This test is right since ABS_USIZE >= ABS_VSIZE. */ 87 if (abs_usize != abs_vsize) 88 { 89 mpn_sub (wp, up, abs_usize, vp, abs_vsize); 90 wsize = abs_usize; 91 MPN_NORMALIZE (wp, wsize); 92 if (usize < 0) 93 wsize = -wsize; 94 } 95 else if (mpn_cmp (up, vp, abs_usize) < 0) 96 { 97 mpn_sub_n (wp, vp, up, abs_usize); 98 wsize = abs_usize; 99 MPN_NORMALIZE (wp, wsize); 100 if (usize >= 0) 101 wsize = -wsize; 102 } 103 else 104 { 105 mpn_sub_n (wp, up, vp, abs_usize); 106 wsize = abs_usize; 107 MPN_NORMALIZE (wp, wsize); 108 if (usize < 0) 109 wsize = -wsize; 110 } 111 } 112 else 113 { 114 /* U and V have same sign. Add them. */ 115 mp_limb_t cy_limb = mpn_add (wp, up, abs_usize, vp, abs_vsize); 116 wp[abs_usize] = cy_limb; 117 wsize = abs_usize + cy_limb; 118 if (usize < 0) 119 wsize = -wsize; 120 } 121 122 SIZ(w) = wsize; 123 } 124