1 /* mpf_ceil, mpf_floor -- round an mpf to an integer. 2 3 Copyright 2001, 2004 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 the GNU Lesser General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or (at your 10 option) any later version. 11 12 The GNU MP Library is distributed in the hope that it will be useful, but 13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 15 License for more details. 16 17 You should have received a copy of the GNU Lesser General Public License 18 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 19 20 #include "gmp.h" 21 #include "gmp-impl.h" 22 23 24 /* dir==1 for ceil, dir==-1 for floor 25 26 Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to 27 mpf_set if u is already an integer. */ 28 29 static void __gmpf_ceil_or_floor __GMP_PROTO ((REGPARM_2_1 (mpf_ptr, mpf_srcptr, int))) REGPARM_ATTR (1); 30 #define mpf_ceil_or_floor(r,u,dir) __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir)) 31 32 REGPARM_ATTR (1) static void 33 mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir) 34 { 35 mp_ptr rp, up, p; 36 mp_size_t size, asize, prec; 37 mp_exp_t exp; 38 39 size = SIZ(u); 40 if (size == 0) 41 { 42 zero: 43 SIZ(r) = 0; 44 EXP(r) = 0; 45 return; 46 } 47 48 rp = PTR(r); 49 exp = EXP(u); 50 if (exp <= 0) 51 { 52 /* u is only a fraction */ 53 if ((size ^ dir) < 0) 54 goto zero; 55 rp[0] = 1; 56 EXP(r) = 1; 57 SIZ(r) = dir; 58 return; 59 } 60 EXP(r) = exp; 61 62 up = PTR(u); 63 asize = ABS (size); 64 up += asize; 65 66 /* skip fraction part of u */ 67 asize = MIN (asize, exp); 68 69 /* don't lose precision in the copy */ 70 prec = PREC (r) + 1; 71 72 /* skip excess over target precision */ 73 asize = MIN (asize, prec); 74 75 up -= asize; 76 77 if ((size ^ dir) >= 0) 78 { 79 /* rounding direction matches sign, must increment if ignored part is 80 non-zero */ 81 for (p = PTR(u); p != up; p++) 82 { 83 if (*p != 0) 84 { 85 if (mpn_add_1 (rp, up, asize, CNST_LIMB(1))) 86 { 87 /* was all 0xFF..FFs, which have become zeros, giving just 88 a carry */ 89 rp[0] = 1; 90 asize = 1; 91 EXP(r)++; 92 } 93 SIZ(r) = (size >= 0 ? asize : -asize); 94 return; 95 } 96 } 97 } 98 99 SIZ(r) = (size >= 0 ? asize : -asize); 100 if (rp != up) 101 MPN_COPY_INCR (rp, up, asize); 102 } 103 104 105 void 106 mpf_ceil (mpf_ptr r, mpf_srcptr u) 107 { 108 mpf_ceil_or_floor (r, u, 1); 109 } 110 111 void 112 mpf_floor (mpf_ptr r, mpf_srcptr u) 113 { 114 mpf_ceil_or_floor (r, u, -1); 115 } 116