1 /* mpz_add_ui, mpz_sub_ui -- Add or subtract an mpz_t and an unsigned 2 one-word integer. 3 4 Copyright 1991, 1993, 1994, 1996, 1999-2002, 2004, 2012, 2013, 2015 5 Free Software Foundation, Inc. 6 7 This file is part of the GNU MP Library. 8 9 The GNU MP Library is free software; you can redistribute it and/or modify 10 it under the terms of either: 11 12 * the GNU Lesser General Public License as published by the Free 13 Software Foundation; either version 3 of the License, or (at your 14 option) any later version. 15 16 or 17 18 * the GNU General Public License as published by the Free Software 19 Foundation; either version 2 of the License, or (at your option) any 20 later version. 21 22 or both in parallel, as here. 23 24 The GNU MP Library is distributed in the hope that it will be useful, but 25 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 26 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 27 for more details. 28 29 You should have received copies of the GNU General Public License and the 30 GNU Lesser General Public License along with the GNU MP Library. If not, 31 see https://www.gnu.org/licenses/. */ 32 33 #include "gmp-impl.h" 34 35 36 #ifdef OPERATION_add_ui 37 #define FUNCTION mpz_add_ui 38 #define FUNCTION2 mpz_add 39 #define VARIATION_CMP >= 40 #define VARIATION_NEG 41 #define VARIATION_UNNEG - 42 #endif 43 44 #ifdef OPERATION_sub_ui 45 #define FUNCTION mpz_sub_ui 46 #define FUNCTION2 mpz_sub 47 #define VARIATION_CMP < 48 #define VARIATION_NEG - 49 #define VARIATION_UNNEG 50 #endif 51 52 #ifndef FUNCTION 53 Error, need OPERATION_add_ui or OPERATION_sub_ui 54 #endif 55 56 57 void 58 FUNCTION (mpz_ptr w, mpz_srcptr u, unsigned long int vval) 59 { 60 mp_srcptr up; 61 mp_ptr wp; 62 mp_size_t usize, wsize; 63 mp_size_t abs_usize; 64 65 #if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */ 66 if (vval > GMP_NUMB_MAX) 67 { 68 mpz_t v; 69 mp_limb_t vl[2]; 70 PTR(v) = vl; 71 vl[0] = vval & GMP_NUMB_MASK; 72 vl[1] = vval >> GMP_NUMB_BITS; 73 SIZ(v) = 2; 74 FUNCTION2 (w, u, v); 75 return; 76 } 77 #endif 78 79 usize = SIZ (u); 80 if (usize == 0) 81 { 82 MPZ_NEWALLOC (w, 1)[0] = vval; 83 SIZ (w) = VARIATION_NEG (vval != 0); 84 return; 85 } 86 87 abs_usize = ABS (usize); 88 89 /* If not space for W (and possible carry), increase space. */ 90 wp = MPZ_REALLOC (w, abs_usize + 1); 91 92 /* These must be after realloc (U may be the same as W). */ 93 up = PTR (u); 94 95 if (usize VARIATION_CMP 0) 96 { 97 mp_limb_t cy; 98 cy = mpn_add_1 (wp, up, abs_usize, (mp_limb_t) vval); 99 wp[abs_usize] = cy; 100 wsize = VARIATION_NEG (abs_usize + cy); 101 } 102 else 103 { 104 /* The signs are different. Need exact comparison to determine 105 which operand to subtract from which. */ 106 if (abs_usize == 1 && up[0] < vval) 107 { 108 wp[0] = vval - up[0]; 109 wsize = VARIATION_NEG 1; 110 } 111 else 112 { 113 mpn_sub_1 (wp, up, abs_usize, (mp_limb_t) vval); 114 /* Size can decrease with at most one limb. */ 115 wsize = VARIATION_UNNEG (abs_usize - (wp[abs_usize - 1] == 0)); 116 } 117 } 118 119 SIZ (w) = wsize; 120 } 121