1 /* mpf_ceil, mpf_floor -- round an mpf to an integer. 2 3 Copyright 2001, 2004, 2012 Free Software Foundation, Inc. 4 5 This file is part of the GNU MP Library. 6 7 The GNU MP Library is free software; you can redistribute it and/or modify 8 it 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 14 or 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 20 or both in parallel, as here. 21 22 The GNU MP Library is distributed in the hope that it will be useful, but 23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 24 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 25 for more details. 26 27 You should have received copies of the GNU General Public License and the 28 GNU Lesser General Public License along with the GNU MP Library. If not, 29 see https://www.gnu.org/licenses/. */ 30 31 #include "gmp-impl.h" 32 33 34 /* dir==1 for ceil, dir==-1 for floor 35 36 Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to 37 mpf_set if u is already an integer. */ 38 39 static void __gmpf_ceil_or_floor (REGPARM_2_1 (mpf_ptr, mpf_srcptr, int)) REGPARM_ATTR (1); 40 #define mpf_ceil_or_floor(r,u,dir) __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir)) 41 42 REGPARM_ATTR (1) static void 43 mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir) 44 { 45 mp_ptr rp, up, p; 46 mp_size_t size, asize, prec; 47 mp_exp_t exp; 48 49 size = SIZ(u); 50 if (size == 0) 51 { 52 zero: 53 SIZ(r) = 0; 54 EXP(r) = 0; 55 return; 56 } 57 58 rp = PTR(r); 59 exp = EXP(u); 60 if (exp <= 0) 61 { 62 /* u is only a fraction */ 63 if ((size ^ dir) < 0) 64 goto zero; 65 rp[0] = 1; 66 EXP(r) = 1; 67 SIZ(r) = dir; 68 return; 69 } 70 EXP(r) = exp; 71 72 up = PTR(u); 73 asize = ABS (size); 74 up += asize; 75 76 /* skip fraction part of u */ 77 asize = MIN (asize, exp); 78 79 /* don't lose precision in the copy */ 80 prec = PREC (r) + 1; 81 82 /* skip excess over target precision */ 83 asize = MIN (asize, prec); 84 85 up -= asize; 86 87 if ((size ^ dir) >= 0) 88 { 89 /* rounding direction matches sign, must increment if ignored part is 90 non-zero */ 91 for (p = PTR(u); p != up; p++) 92 { 93 if (*p != 0) 94 { 95 if (mpn_add_1 (rp, up, asize, CNST_LIMB(1))) 96 { 97 /* was all 0xFF..FFs, which have become zeros, giving just 98 a carry */ 99 rp[0] = 1; 100 asize = 1; 101 EXP(r)++; 102 } 103 SIZ(r) = (size >= 0 ? asize : -asize); 104 return; 105 } 106 } 107 } 108 109 SIZ(r) = (size >= 0 ? asize : -asize); 110 if (rp != up) 111 MPN_COPY_INCR (rp, up, asize); 112 } 113 114 115 void 116 mpf_ceil (mpf_ptr r, mpf_srcptr u) 117 { 118 mpf_ceil_or_floor (r, u, 1); 119 } 120 121 void 122 mpf_floor (mpf_ptr r, mpf_srcptr u) 123 { 124 mpf_ceil_or_floor (r, u, -1); 125 } 126