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aors.c revision 1.1.1.4 
      1 /* mpq_add, mpq_sub -- add or subtract rational numbers.
      2 
      3 Copyright 1991, 1994-1997, 2000, 2001, 2004, 2005 Free Software Foundation,
      4 Inc.
      5 
      6 This file is part of the GNU MP Library.
      7 
      8 The GNU MP Library is free software; you can redistribute it and/or modify
      9 it under the terms of either:
     10 
     11   * the GNU Lesser General Public License as published by the Free
     12     Software Foundation; either version 3 of the License, or (at your
     13     option) any later version.
     14 
     15 or
     16 
     17   * the GNU General Public License as published by the Free Software
     18     Foundation; either version 2 of the License, or (at your option) any
     19     later version.
     20 
     21 or both in parallel, as here.
     22 
     23 The GNU MP Library is distributed in the hope that it will be useful, but
     24 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
     25 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     26 for more details.
     27 
     28 You should have received copies of the GNU General Public License and the
     29 GNU Lesser General Public License along with the GNU MP Library.  If not,
     30 see https://www.gnu.org/licenses/.  */
     31 
     32 #include "gmp-impl.h"
     33 
     34 
     35 static void __gmpq_aors (REGPARM_3_1 (mpq_ptr, mpq_srcptr, mpq_srcptr, void (*) (mpz_ptr, mpz_srcptr, mpz_srcptr))) REGPARM_ATTR (1);
     36 #define mpq_aors(w,x,y,fun)  __gmpq_aors (REGPARM_3_1 (w, x, y, fun))
     37 
     38 REGPARM_ATTR (1) static void
     39 mpq_aors (mpq_ptr rop, mpq_srcptr op1, mpq_srcptr op2,
     40           void (*fun) (mpz_ptr, mpz_srcptr, mpz_srcptr))
     41 {
     42   mpz_t gcd;
     43   mpz_t tmp1, tmp2;
     44   mp_size_t op1_num_size = ABSIZ(NUM(op1));
     45   mp_size_t op1_den_size =   SIZ(DEN(op1));
     46   mp_size_t op2_num_size = ABSIZ(NUM(op2));
     47   mp_size_t op2_den_size =   SIZ(DEN(op2));
     48   TMP_DECL;
     49 
     50   TMP_MARK;
     51   MPZ_TMP_INIT (gcd, MIN (op1_den_size, op2_den_size));
     52   MPZ_TMP_INIT (tmp1, op1_num_size + op2_den_size);
     53   MPZ_TMP_INIT (tmp2, op2_num_size + op1_den_size);
     54 
     55   /* ROP might be identical to either operand, so don't store the
     56      result there until we are finished with the input operands.  We
     57      dare to overwrite the numerator of ROP when we are finished
     58      with the numerators of OP1 and OP2.  */
     59 
     60   mpz_gcd (gcd, DEN(op1), DEN(op2));
     61   if (! MPZ_EQUAL_1_P (gcd))
     62     {
     63       mpz_t t;
     64 
     65       MPZ_TMP_INIT (t, MAX (op1_num_size + op2_den_size,
     66 	     op2_num_size + op1_den_size) + 2 - SIZ(gcd));
     67 
     68       mpz_divexact_gcd (t, DEN(op2), gcd);
     69       mpz_divexact_gcd (tmp2, DEN(op1), gcd);
     70 
     71       mpz_mul (tmp1, NUM(op1), t);
     72       mpz_mul (t, NUM(op2), tmp2);
     73 
     74       (*fun) (t, tmp1, t);
     75 
     76       mpz_gcd (gcd, t, gcd);
     77       if (MPZ_EQUAL_1_P (gcd))
     78         {
     79           mpz_set (NUM(rop), t);
     80           mpz_mul (DEN(rop), DEN(op2), tmp2);
     81         }
     82       else
     83         {
     84           mpz_divexact_gcd (NUM(rop), t, gcd);
     85           mpz_divexact_gcd (tmp1, DEN(op2), gcd);
     86           mpz_mul (DEN(rop), tmp1, tmp2);
     87         }
     88     }
     89   else
     90     {
     91       /* The common divisor is 1.  This is the case (for random input) with
     92 	 probability 6/(pi**2), which is about 60.8%.  */
     93       mpz_mul (tmp1, NUM(op1), DEN(op2));
     94       mpz_mul (tmp2, NUM(op2), DEN(op1));
     95       (*fun) (NUM(rop), tmp1, tmp2);
     96       mpz_mul (DEN(rop), DEN(op1), DEN(op2));
     97     }
     98   TMP_FREE;
     99 }
    100 
    101 
    102 void
    103 mpq_add (mpq_ptr rop, mpq_srcptr op1, mpq_srcptr op2)
    104 {
    105   mpq_aors (rop, op1, op2, mpz_add);
    106 }
    107 
    108 void
    109 mpq_sub (mpq_ptr rop, mpq_srcptr op1, mpq_srcptr op2)
    110 {
    111   mpq_aors (rop, op1, op2, mpz_sub);
    112 }
    113