1/* mpf_add -- Add two floats. 2 3Copyright 1993, 1994, 1996, 2000, 2001, 2005 Free Software Foundation, Inc. 4 5This file is part of the GNU MP Library. 6 7The GNU MP Library is free software; you can redistribute it and/or modify 8it under the terms of either: 9 10 * the GNU Lesser General Public License as published by the Free 11 Software Foundation; either version 3 of the License, or (at your 12 option) any later version. 13 14or 15 16 * the GNU General Public License as published by the Free Software 17 Foundation; either version 2 of the License, or (at your option) any 18 later version. 19 20or both in parallel, as here. 21 22The GNU MP Library is distributed in the hope that it will be useful, but 23WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 24or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 25for more details. 26 27You should have received copies of the GNU General Public License and the 28GNU Lesser General Public License along with the GNU MP Library. If not, 29see https://www.gnu.org/licenses/. */ 30 31#include "gmp-impl.h" 32 33void 34mpf_add (mpf_ptr r, mpf_srcptr u, mpf_srcptr v) 35{ 36 mp_srcptr up, vp; 37 mp_ptr rp, tp; 38 mp_size_t usize, vsize, rsize; 39 mp_size_t prec; 40 mp_exp_t uexp; 41 mp_size_t ediff; 42 mp_limb_t cy; 43 int negate; 44 TMP_DECL; 45 46 usize = u->_mp_size; 47 vsize = v->_mp_size; 48 49 /* Handle special cases that don't work in generic code below. */ 50 if (usize == 0) 51 { 52 set_r_v_maybe: 53 if (r != v) 54 mpf_set (r, v); 55 return; 56 } 57 if (vsize == 0) 58 { 59 v = u; 60 goto set_r_v_maybe; 61 } 62 63 /* If signs of U and V are different, perform subtraction. */ 64 if ((usize ^ vsize) < 0) 65 { 66 __mpf_struct v_negated; 67 v_negated._mp_size = -vsize; 68 v_negated._mp_exp = v->_mp_exp; 69 v_negated._mp_d = v->_mp_d; 70 mpf_sub (r, u, &v_negated); 71 return; 72 } 73 74 TMP_MARK; 75 76 /* Signs are now known to be the same. */ 77 negate = usize < 0; 78 79 /* Make U be the operand with the largest exponent. */ 80 if (u->_mp_exp < v->_mp_exp) 81 { 82 mpf_srcptr t; 83 t = u; u = v; v = t; 84 usize = u->_mp_size; 85 vsize = v->_mp_size; 86 } 87 88 usize = ABS (usize); 89 vsize = ABS (vsize); 90 up = u->_mp_d; 91 vp = v->_mp_d; 92 rp = r->_mp_d; 93 prec = r->_mp_prec; 94 uexp = u->_mp_exp; 95 ediff = u->_mp_exp - v->_mp_exp; 96 97 /* If U extends beyond PREC, ignore the part that does. */ 98 if (usize > prec) 99 { 100 up += usize - prec; 101 usize = prec; 102 } 103 104 /* If V extends beyond PREC, ignore the part that does. 105 Note that this may make vsize negative. */ 106 if (vsize + ediff > prec) 107 { 108 vp += vsize + ediff - prec; 109 vsize = prec - ediff; 110 } 111 112#if 0 113 /* Locate the least significant non-zero limb in (the needed parts 114 of) U and V, to simplify the code below. */ 115 while (up[0] == 0) 116 up++, usize--; 117 while (vp[0] == 0) 118 vp++, vsize--; 119#endif 120 121 /* Allocate temp space for the result. Allocate 122 just vsize + ediff later??? */ 123 tp = TMP_ALLOC_LIMBS (prec); 124 125 if (ediff >= prec) 126 { 127 /* V completely cancelled. */ 128 if (rp != up) 129 MPN_COPY_INCR (rp, up, usize); 130 rsize = usize; 131 } 132 else 133 { 134 /* uuuu | uuuu | uuuu | uuuu | uuuu */ 135 /* vvvvvvv | vv | vvvvv | v | vv */ 136 137 if (usize > ediff) 138 { 139 /* U and V partially overlaps. */ 140 if (vsize + ediff <= usize) 141 { 142 /* uuuu */ 143 /* v */ 144 mp_size_t size; 145 size = usize - ediff - vsize; 146 MPN_COPY (tp, up, size); 147 cy = mpn_add (tp + size, up + size, usize - size, vp, vsize); 148 rsize = usize; 149 } 150 else 151 { 152 /* uuuu */ 153 /* vvvvv */ 154 mp_size_t size; 155 size = vsize + ediff - usize; 156 MPN_COPY (tp, vp, size); 157 cy = mpn_add (tp + size, up, usize, vp + size, usize - ediff); 158 rsize = vsize + ediff; 159 } 160 } 161 else 162 { 163 /* uuuu */ 164 /* vv */ 165 mp_size_t size; 166 size = vsize + ediff - usize; 167 MPN_COPY (tp, vp, vsize); 168 MPN_ZERO (tp + vsize, ediff - usize); 169 MPN_COPY (tp + size, up, usize); 170 cy = 0; 171 rsize = size + usize; 172 } 173 174 MPN_COPY (rp, tp, rsize); 175 rp[rsize] = cy; 176 rsize += cy; 177 uexp += cy; 178 } 179 180 r->_mp_size = negate ? -rsize : rsize; 181 r->_mp_exp = uexp; 182 TMP_FREE; 183} 184