| Austin Schuh | bb1338c | 2024-06-15 19:31:16 -0700 | [diff] [blame] | 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 | } |