github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpq/div.c (about)

     1  /* mpq_div -- divide two rational numbers.
     2  
     3  Copyright 1991, 1994-1996, 2000, 2001, 2015 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.h"
    32  #include "gmp-impl.h"
    33  
    34  
    35  void
    36  mpq_div (mpq_ptr quot, mpq_srcptr op1, mpq_srcptr op2)
    37  {
    38    mpz_t gcd1, gcd2;
    39    mpz_t tmp1, tmp2;
    40    mp_size_t op1_size;
    41    mp_size_t op2_size;
    42    mp_size_t alloc;
    43    TMP_DECL;
    44  
    45    op2_size = SIZ(NUM(op2));
    46  
    47    if (UNLIKELY (op2_size == 0))
    48      DIVIDE_BY_ZERO;
    49  
    50    if (UNLIKELY (quot == op2))
    51      {
    52        if (op1 == op2)
    53  	{
    54  	  PTR(NUM(quot))[0] = 1;
    55  	  SIZ(NUM(quot)) = 1;
    56  	  PTR(DEN(quot))[0] = 1;
    57  	  SIZ(DEN(quot)) = 1;
    58  	  return;
    59  	}
    60  
    61        /* We checked for op1 == op2: we are not in the x=x/x case.
    62  	 We compute x=y/x by computing x=inv(x)*y */
    63        MPN_PTR_SWAP (PTR(NUM(quot)), ALLOC(NUM(quot)),
    64  		    PTR(DEN(quot)), ALLOC(DEN(quot)));
    65        if (op2_size > 0)
    66  	{
    67  	  SIZ(NUM(quot)) = SIZ(DEN(quot));
    68  	  SIZ(DEN(quot)) = op2_size;
    69  	}
    70        else
    71  	{
    72  	  SIZ(NUM(quot)) = - SIZ(DEN(quot));
    73  	  SIZ(DEN(quot)) = - op2_size;
    74  	}
    75        mpq_mul (quot, quot, op1);
    76        return;
    77      }
    78  
    79    op1_size = ABSIZ(NUM(op1));
    80  
    81    if (op1_size == 0)
    82      {
    83        /* We special case this to simplify allocation logic; gcd(0,x) = x
    84  	 is a singular case for the allocations.  */
    85        SIZ(NUM(quot)) = 0;
    86        PTR(DEN(quot))[0] = 1;
    87        SIZ(DEN(quot)) = 1;
    88        return;
    89      }
    90  
    91    op2_size = ABS(op2_size);
    92  
    93    TMP_MARK;
    94  
    95    alloc = MIN (op1_size, op2_size);
    96    MPZ_TMP_INIT (gcd1, alloc);
    97  
    98    alloc = MAX (op1_size, op2_size);
    99    MPZ_TMP_INIT (tmp1, alloc);
   100  
   101    op2_size = SIZ(DEN(op2));
   102    op1_size = SIZ(DEN(op1));
   103  
   104    alloc = MIN (op1_size, op2_size);
   105    MPZ_TMP_INIT (gcd2, alloc);
   106  
   107    alloc = MAX (op1_size, op2_size);
   108    MPZ_TMP_INIT (tmp2, alloc);
   109  
   110    /* QUOT might be identical to OP1, so don't store the result there
   111       until we are finished with the input operand.  We can overwrite
   112       the numerator of QUOT when we are finished with the numerator of
   113       OP1. */
   114  
   115    mpz_gcd (gcd1, NUM(op1), NUM(op2));
   116    mpz_gcd (gcd2, DEN(op2), DEN(op1));
   117  
   118    mpz_divexact_gcd (tmp1, NUM(op1), gcd1);
   119    mpz_divexact_gcd (tmp2, DEN(op2), gcd2);
   120  
   121    mpz_mul (NUM(quot), tmp1, tmp2);
   122  
   123    mpz_divexact_gcd (tmp1, NUM(op2), gcd1);
   124    mpz_divexact_gcd (tmp2, DEN(op1), gcd2);
   125  
   126    mpz_mul (DEN(quot), tmp1, tmp2);
   127  
   128    /* Keep the denominator positive.  */
   129    if (SIZ(DEN(quot)) < 0)
   130      {
   131        SIZ(DEN(quot)) = -SIZ(DEN(quot));
   132        SIZ(NUM(quot)) = -SIZ(NUM(quot));
   133      }
   134  
   135    TMP_FREE;
   136  }