1 /* mpfr_cmp -- compare two floating-point numbers 2 3 Copyright 1999, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 4 Contributed by the Arenaire and Caramel projects, INRIA. 5 6 This file is part of the GNU MPFR Library. 7 8 The GNU MPFR Library is free software; you can redistribute it and/or modify 9 it under the terms of the GNU Lesser General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or (at your 11 option) any later version. 12 13 The GNU MPFR Library is distributed in the hope that it will be useful, but 14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16 License for more details. 17 18 You should have received a copy of the GNU Lesser General Public License 19 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 22 23 #include "mpfr-impl.h" 24 25 /* returns 0 iff b = sign(s) * c 26 a positive value iff b > sign(s) * c 27 a negative value iff b < sign(s) * c 28 returns 0 and sets erange flag if b and/or c is NaN. 29 */ 30 31 int 32 mpfr_cmp3 (mpfr_srcptr b, mpfr_srcptr c, int s) 33 { 34 mpfr_exp_t be, ce; 35 mp_size_t bn, cn; 36 mp_limb_t *bp, *cp; 37 38 s = MPFR_MULT_SIGN( s , MPFR_SIGN(c) ); 39 40 if (MPFR_ARE_SINGULAR(b, c)) 41 { 42 if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c)) 43 { 44 MPFR_SET_ERANGE (); 45 return 0; 46 } 47 else if (MPFR_IS_INF(b)) 48 { 49 if (MPFR_IS_INF(c) && s == MPFR_SIGN(b) ) 50 return 0; 51 else 52 return MPFR_SIGN(b); 53 } 54 else if (MPFR_IS_INF(c)) 55 return -s; 56 else if (MPFR_IS_ZERO(b)) 57 return MPFR_IS_ZERO(c) ? 0 : -s; 58 else /* necessarily c=0 */ 59 return MPFR_SIGN(b); 60 } 61 /* b and c are real numbers */ 62 if (s != MPFR_SIGN(b)) 63 return MPFR_SIGN(b); 64 65 /* now signs are equal */ 66 67 be = MPFR_GET_EXP (b); 68 ce = MPFR_GET_EXP (c); 69 if (be > ce) 70 return s; 71 if (be < ce) 72 return -s; 73 74 /* both signs and exponents are equal */ 75 76 bn = (MPFR_PREC(b)-1)/GMP_NUMB_BITS; 77 cn = (MPFR_PREC(c)-1)/GMP_NUMB_BITS; 78 79 bp = MPFR_MANT(b); 80 cp = MPFR_MANT(c); 81 82 for ( ; bn >= 0 && cn >= 0; bn--, cn--) 83 { 84 if (bp[bn] > cp[cn]) 85 return s; 86 if (bp[bn] < cp[cn]) 87 return -s; 88 } 89 for ( ; bn >= 0; bn--) 90 if (bp[bn]) 91 return s; 92 for ( ; cn >= 0; cn--) 93 if (cp[cn]) 94 return -s; 95 96 return 0; 97 } 98 99 #undef mpfr_cmp 100 int 101 mpfr_cmp (mpfr_srcptr b, mpfr_srcptr c) 102 { 103 return mpfr_cmp3 (b, c, 1); 104 } 105