/* mpq_div -- divide two rational numbers.

Copyright 1991, 1994-1996, 2000, 2001, 2015 Free Software Foundation, Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify

it under the terms of either:

  * the GNU Lesser General Public License as published by the Free

    Software Foundation; either version 3 of the License, or (at your

    option) any later version.

or

  * the GNU General Public License as published by the Free Software

    Foundation; either version 2 of the License, or (at your option) any

    later version.

or both in parallel, as here.

The GNU MP Library is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received copies of the GNU General Public License and the

GNU Lesser General Public License along with the GNU MP Library.  If not,

see https://www.gnu.org/licenses/.  */

#include "gmp.h"

#include "gmp-impl.h"

void

mpq_div (mpq_ptr quot, mpq_srcptr op1, mpq_srcptr op2)

{

  mpz_t gcd1, gcd2;

  mpz_t tmp1, tmp2;

  mp_size_t op1_size;

  mp_size_t op2_size;

  mp_size_t alloc;

  TMP_DECL;

  op2_size = SIZ(NUM(op2));

  if (UNLIKELY (op2_size == 0))

    DIVIDE_BY_ZERO;

  if (UNLIKELY (quot == op2))

    {

      if (op1 == op2)

	{

	  PTR(NUM(quot))[0] = 1;

	  SIZ(NUM(quot)) = 1;

	  PTR(DEN(quot))[0] = 1;

	  SIZ(DEN(quot)) = 1;

	  return;

	}

      /* We checked for op1 == op2: we are not in the x=x/x case.

	 We compute x=y/x by computing x=inv(x)*y */

      MPN_PTR_SWAP (PTR(NUM(quot)), ALLOC(NUM(quot)),

		    PTR(DEN(quot)), ALLOC(DEN(quot)));

      if (op2_size > 0)

	{

	  SIZ(NUM(quot)) = SIZ(DEN(quot));

	  SIZ(DEN(quot)) = op2_size;

	}

      else

	{

	  SIZ(NUM(quot)) = - SIZ(DEN(quot));

	  SIZ(DEN(quot)) = - op2_size;

	}

      mpq_mul (quot, quot, op1);

      return;

    }

  op1_size = ABSIZ(NUM(op1));

  if (op1_size == 0)

    {

      /* We special case this to simplify allocation logic; gcd(0,x) = x

	 is a singular case for the allocations.  */

      SIZ(NUM(quot)) = 0;

      PTR(DEN(quot))[0] = 1;

      SIZ(DEN(quot)) = 1;

      return;

    }

  op2_size = ABS(op2_size);

  TMP_MARK;

  alloc = MIN (op1_size, op2_size);

  MPZ_TMP_INIT (gcd1, alloc);

  alloc = MAX (op1_size, op2_size);

  MPZ_TMP_INIT (tmp1, alloc);

  op2_size = SIZ(DEN(op2));

  op1_size = SIZ(DEN(op1));

  alloc = MIN (op1_size, op2_size);

  MPZ_TMP_INIT (gcd2, alloc);

  alloc = MAX (op1_size, op2_size);

  MPZ_TMP_INIT (tmp2, alloc);

  /* QUOT might be identical to OP1, so don't store the result there

     until we are finished with the input operand.  We can overwrite

     the numerator of QUOT when we are finished with the numerator of

     OP1. */

  mpz_gcd (gcd1, NUM(op1), NUM(op2));

  mpz_gcd (gcd2, DEN(op2), DEN(op1));

  mpz_divexact_gcd (tmp1, NUM(op1), gcd1);

  mpz_divexact_gcd (tmp2, DEN(op2), gcd2);

  mpz_mul (NUM(quot), tmp1, tmp2);

  mpz_divexact_gcd (tmp1, NUM(op2), gcd1);

  mpz_divexact_gcd (tmp2, DEN(op1), gcd2);

  mpz_mul (DEN(quot), tmp1, tmp2);

  /* Keep the denominator positive.  */

  if (SIZ(DEN(quot)) < 0)

    {

      SIZ(DEN(quot)) = -SIZ(DEN(quot));

      SIZ(NUM(quot)) = -SIZ(NUM(quot));

    }

  TMP_FREE;

}