/* Implementations of operations between mpfr and mpz/mpq data

Copyright 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
Contributed by the AriC and Caramel projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of 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.

The GNU MPFR 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 Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#define MPFR_NEED_LONGLONG_H
#include "mpfr-impl.h"

/* Init and set a mpfr_t with enough precision to store a mpz.
   This function should be called in the extended exponent range. */
static void
init_set_z (mpfr_ptr t, mpz_srcptr z)
{
  mpfr_prec_t p;
  int i;

  if (mpz_size (z) <= 1)
    p = GMP_NUMB_BITS;
  else
    MPFR_MPZ_SIZEINBASE2 (p, z);
  mpfr_init2 (t, p);
  i = mpfr_set_z (t, z, MPFR_RNDN);
  /* Possible assertion failure in case of overflow. Such cases,
     which imply that z is huge (if the function is called in
     the extended exponent range), are currently not supported,
     just like precisions around MPFR_PREC_MAX. */
  MPFR_ASSERTN (i == 0);  (void) i; /* use i to avoid a warning */
}

/* Init, set a mpfr_t with enough precision to store a mpz_t without round,
   call the function, and clear the allocated mpfr_t  */
static int
foo (mpfr_ptr x, mpfr_srcptr y, mpz_srcptr z, mpfr_rnd_t r,
     int (*f)(mpfr_ptr, mpfr_srcptr, mpfr_srcptr, mpfr_rnd_t))
{
  mpfr_t t;
  int i;
  MPFR_SAVE_EXPO_DECL (expo);

  MPFR_SAVE_EXPO_MARK (expo);
  init_set_z (t, z);  /* There should be no exceptions. */
  i = (*f) (x, y, t, r);
  MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
  mpfr_clear (t);
  MPFR_SAVE_EXPO_FREE (expo);
  return mpfr_check_range (x, i, r);
}

static int
foo2 (mpfr_ptr x, mpz_srcptr y, mpfr_srcptr z, mpfr_rnd_t r,
     int (*f)(mpfr_ptr, mpfr_srcptr, mpfr_srcptr, mpfr_rnd_t))
{
  mpfr_t t;
  int i;
  MPFR_SAVE_EXPO_DECL (expo);

  MPFR_SAVE_EXPO_MARK (expo);
  init_set_z (t, y);  /* There should be no exceptions. */
  i = (*f) (x, t, z, r);
  MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
  mpfr_clear (t);
  MPFR_SAVE_EXPO_FREE (expo);
  return mpfr_check_range (x, i, r);
}

int
mpfr_mul_z (mpfr_ptr y, mpfr_srcptr x, mpz_srcptr z, mpfr_rnd_t r)
{
  return foo (y, x, z, r, mpfr_mul);
}

int
mpfr_div_z (mpfr_ptr y, mpfr_srcptr x, mpz_srcptr z, mpfr_rnd_t r)
{
  return foo (y, x, z, r, mpfr_div);
}

int
mpfr_add_z (mpfr_ptr y, mpfr_srcptr x, mpz_srcptr z, mpfr_rnd_t r)
{
  /* Mpz 0 is unsigned */
  if (MPFR_UNLIKELY (mpz_sgn (z) == 0))
    return mpfr_set (y, x, r);
  else
    return foo (y, x, z, r, mpfr_add);
}

int
mpfr_sub_z (mpfr_ptr y, mpfr_srcptr x, mpz_srcptr z, mpfr_rnd_t r)
{
  /* Mpz 0 is unsigned */
  if (MPFR_UNLIKELY (mpz_sgn (z) == 0))
    return mpfr_set (y, x, r);
  else
    return foo (y, x, z, r, mpfr_sub);
}

int
mpfr_z_sub (mpfr_ptr y, mpz_srcptr x, mpfr_srcptr z, mpfr_rnd_t r)
{
  /* Mpz 0 is unsigned */
  if (MPFR_UNLIKELY (mpz_sgn (x) == 0))
    return mpfr_neg (y, z, r);
  else
    return foo2 (y, x, z, r, mpfr_sub);
}

int
mpfr_cmp_z (mpfr_srcptr x, mpz_srcptr z)
{
  mpfr_t t;
  int res;
  mpfr_prec_t p;
  unsigned int flags;

  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
    return mpfr_cmp_si (x, mpz_sgn (z));

  if (mpz_size (z) <= 1)
    p = GMP_NUMB_BITS;
  else
    MPFR_MPZ_SIZEINBASE2 (p, z);
  mpfr_init2 (t, p);
  flags = __gmpfr_flags;
  if (mpfr_set_z (t, z, MPFR_RNDN))
    {
      /* overflow (t is an infinity) or underflow */
      mpfr_div_2ui (t, t, 2, MPFR_RNDZ);  /* if underflow, set t to zero */
      __gmpfr_flags = flags;  /* restore the flags */
      /* The real value of t (= z), which falls outside the exponent range,
         has been replaced by an equivalent value for the comparison: zero
         or an infinity. */
    }
  res = mpfr_cmp (x, t);
  mpfr_clear (t);
  return res;
}

/* Compute y = RND(x*n/d), where n and d are mpz integers.
   An integer 0 is assumed to have a positive sign.
   This function is used by mpfr_mul_q and mpfr_div_q.
   Note: the status of the rational 0/(-1) is not clear (if there is
   a signed infinity, there should be a signed zero). But infinities
   are not currently supported/documented in GMP, and if the rational
   is canonicalized as it should be, the case 0/(-1) cannot occur. */
static int
mpfr_muldiv_z (mpfr_ptr y, mpfr_srcptr x, mpz_srcptr n, mpz_srcptr d,
               mpfr_rnd_t rnd_mode)
{
  if (MPFR_UNLIKELY (mpz_sgn (n) == 0))
    {
      if (MPFR_UNLIKELY (mpz_sgn (d) == 0))
        MPFR_SET_NAN (y);
      else
        {
          mpfr_mul_ui (y, x, 0, MPFR_RNDN);  /* exact: +0, -0 or NaN */
          if (MPFR_UNLIKELY (mpz_sgn (d) < 0))
            MPFR_CHANGE_SIGN (y);
        }
      return 0;
    }
  else if (MPFR_UNLIKELY (mpz_sgn (d) == 0))
    {
      mpfr_div_ui (y, x, 0, MPFR_RNDN);  /* exact: +Inf, -Inf or NaN */
      if (MPFR_UNLIKELY (mpz_sgn (n) < 0))
        MPFR_CHANGE_SIGN (y);
      return 0;
    }
  else
    {
      mpfr_prec_t p;
      mpfr_t tmp;
      int inexact;
      MPFR_SAVE_EXPO_DECL (expo);

      MPFR_SAVE_EXPO_MARK (expo);

      /* With the current MPFR code, using mpfr_mul_z and mpfr_div_z
         for the general case should be faster than doing everything
         in mpn, mpz and/or mpq. MPFR_SAVE_EXPO_MARK could be avoided
         here, but it would be more difficult to handle corner cases. */
      MPFR_MPZ_SIZEINBASE2 (p, n);
      mpfr_init2 (tmp, MPFR_PREC (x) + p);
      inexact = mpfr_mul_z (tmp, x, n, MPFR_RNDN);
      /* Since |n| >= 1, an underflow is not possible. And the precision of
         tmp has been chosen so that inexact != 0 iff there's an overflow. */
      if (MPFR_UNLIKELY (inexact != 0))
        {
          mpfr_t x0;
          mpfr_exp_t ex;
          MPFR_BLOCK_DECL (flags);

          /* intermediate overflow case */
          MPFR_ASSERTD (mpfr_inf_p (tmp));
          ex = MPFR_GET_EXP (x);  /* x is a pure FP number */
          MPFR_ALIAS (x0, x, MPFR_SIGN(x), 0);  /* x0 = x / 2^ex */
          MPFR_BLOCK (flags,
                      inexact = mpfr_mul_z (tmp, x0, n, MPFR_RNDN);
                      MPFR_ASSERTD (inexact == 0);
                      inexact = mpfr_div_z (y, tmp, d, rnd_mode);
                      /* Just in case the division underflows
                         (highly unlikely, not supported)... */
                      MPFR_ASSERTN (!MPFR_BLOCK_EXCEP));
          MPFR_EXP (y) += ex;
          /* Detect highly unlikely, not supported corner cases... */
          MPFR_ASSERTN (MPFR_EXP (y) >= __gmpfr_emin && MPFR_IS_PURE_FP (y));
          /* The potential overflow will be detected by mpfr_check_range. */
        }
      else
        inexact = mpfr_div_z (y, tmp, d, rnd_mode);

      mpfr_clear (tmp);

      MPFR_SAVE_EXPO_FREE (expo);
      return mpfr_check_range (y, inexact, rnd_mode);
    }
}

int
mpfr_mul_q (mpfr_ptr y, mpfr_srcptr x, mpq_srcptr z, mpfr_rnd_t rnd_mode)
{
  return mpfr_muldiv_z (y, x, mpq_numref (z), mpq_denref (z), rnd_mode);
}

int
mpfr_div_q (mpfr_ptr y, mpfr_srcptr x, mpq_srcptr z, mpfr_rnd_t rnd_mode)
{
  return mpfr_muldiv_z (y, x, mpq_denref (z), mpq_numref (z), rnd_mode);
}

int
mpfr_add_q (mpfr_ptr y, mpfr_srcptr x, mpq_srcptr z, mpfr_rnd_t rnd_mode)
{
  mpfr_t      t,q;
  mpfr_prec_t p;
  mpfr_exp_t  err;
  int res;
  MPFR_SAVE_EXPO_DECL (expo);
  MPFR_ZIV_DECL (loop);

  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
    {
      if (MPFR_IS_NAN (x))
        {
          MPFR_SET_NAN (y);
          MPFR_RET_NAN;
        }
      else if (MPFR_IS_INF (x))
        {
          if (MPFR_UNLIKELY (mpz_sgn (mpq_denref (z)) == 0 &&
                             MPFR_MULT_SIGN (mpz_sgn (mpq_numref (z)),
                                             MPFR_SIGN (x)) <= 0))
            {
              MPFR_SET_NAN (y);
              MPFR_RET_NAN;
            }
          MPFR_SET_INF (y);
          MPFR_SET_SAME_SIGN (y, x);
          MPFR_RET (0);
        }
      else
        {
          MPFR_ASSERTD (MPFR_IS_ZERO (x));
          if (MPFR_UNLIKELY (mpq_sgn (z) == 0))
            return mpfr_set (y, x, rnd_mode); /* signed 0 - Unsigned 0 */
          else
            return mpfr_set_q (y, z, rnd_mode);
        }
    }

  MPFR_SAVE_EXPO_MARK (expo);

  p = MPFR_PREC (y) + 10;
  mpfr_init2 (t, p);
  mpfr_init2 (q, p);

  MPFR_ZIV_INIT (loop, p);
  for (;;)
    {
      MPFR_BLOCK_DECL (flags);

      res = mpfr_set_q (q, z, MPFR_RNDN);  /* Error <= 1/2 ulp(q) */
      /* If z if @INF@ (1/0), res = 0, so it quits immediately */
      if (MPFR_UNLIKELY (res == 0))
        /* Result is exact so we can add it directly! */
        {
          res = mpfr_add (y, x, q, rnd_mode);
          break;
        }
      MPFR_BLOCK (flags, mpfr_add (t, x, q, MPFR_RNDN));
      /* Error on t is <= 1/2 ulp(t), except in case of overflow/underflow,
         but such an exception is very unlikely as it would be possible
         only if q has a huge numerator or denominator. Not supported! */
      MPFR_ASSERTN (! (MPFR_OVERFLOW (flags) || MPFR_UNDERFLOW (flags)));
      /* Error / ulp(t)      <= 1/2 + 1/2 * 2^(EXP(q)-EXP(t))
         If EXP(q)-EXP(t)>0, <= 2^(EXP(q)-EXP(t)-1)*(1+2^-(EXP(q)-EXP(t)))
                             <= 2^(EXP(q)-EXP(t))
         If EXP(q)-EXP(t)<0, <= 2^0 */
      /* We can get 0, but we can't round since q is inexact */
      if (MPFR_LIKELY (!MPFR_IS_ZERO (t)))
        {
          err = (mpfr_exp_t) p - 1 - MAX (MPFR_GET_EXP(q)-MPFR_GET_EXP(t), 0);
          if (MPFR_LIKELY (MPFR_CAN_ROUND (t, err, MPFR_PREC (y), rnd_mode)))
            {
              res = mpfr_set (y, t, rnd_mode);
              break;
            }
        }
      MPFR_ZIV_NEXT (loop, p);
      mpfr_set_prec (t, p);
      mpfr_set_prec (q, p);
    }
  MPFR_ZIV_FREE (loop);
  mpfr_clear (t);
  mpfr_clear (q);

  MPFR_SAVE_EXPO_FREE (expo);
  return mpfr_check_range (y, res, rnd_mode);
}

int
mpfr_sub_q (mpfr_ptr y, mpfr_srcptr x, mpq_srcptr z,mpfr_rnd_t rnd_mode)
{
  mpfr_t t,q;
  mpfr_prec_t p;
  int res;
  mpfr_exp_t err;
  MPFR_SAVE_EXPO_DECL (expo);
  MPFR_ZIV_DECL (loop);

  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
    {
      if (MPFR_IS_NAN (x))
        {
          MPFR_SET_NAN (y);
          MPFR_RET_NAN;
        }
      else if (MPFR_IS_INF (x))
        {
          if (MPFR_UNLIKELY (mpz_sgn (mpq_denref (z)) == 0 &&
                             MPFR_MULT_SIGN (mpz_sgn (mpq_numref (z)),
                                             MPFR_SIGN (x)) >= 0))
            {
              MPFR_SET_NAN (y);
              MPFR_RET_NAN;
            }
          MPFR_SET_INF (y);
          MPFR_SET_SAME_SIGN (y, x);
          MPFR_RET (0);
        }
      else
        {
          MPFR_ASSERTD (MPFR_IS_ZERO (x));

          if (MPFR_UNLIKELY (mpq_sgn (z) == 0))
            return mpfr_set (y, x, rnd_mode); /* signed 0 - Unsigned 0 */
          else
            {
              res =  mpfr_set_q (y, z, MPFR_INVERT_RND (rnd_mode));
              MPFR_CHANGE_SIGN (y);
              return -res;
            }
        }
    }

  MPFR_SAVE_EXPO_MARK (expo);

  p = MPFR_PREC (y) + 10;
  mpfr_init2 (t, p);
  mpfr_init2 (q, p);

  MPFR_ZIV_INIT (loop, p);
  for(;;)
    {
      MPFR_BLOCK_DECL (flags);

      res = mpfr_set_q(q, z, MPFR_RNDN);  /* Error <= 1/2 ulp(q) */
      /* If z if @INF@ (1/0), res = 0, so it quits immediately */
      if (MPFR_UNLIKELY (res == 0))
        /* Result is exact so we can add it directly!*/
        {
          res = mpfr_sub (y, x, q, rnd_mode);
          break;
        }
      MPFR_BLOCK (flags, mpfr_sub (t, x, q, MPFR_RNDN));
      /* Error on t is <= 1/2 ulp(t), except in case of overflow/underflow,
         but such an exception is very unlikely as it would be possible
         only if q has a huge numerator or denominator. Not supported! */
      MPFR_ASSERTN (! (MPFR_OVERFLOW (flags) || MPFR_UNDERFLOW (flags)));
      /* Error / ulp(t)      <= 1/2 + 1/2 * 2^(EXP(q)-EXP(t))
         If EXP(q)-EXP(t)>0, <= 2^(EXP(q)-EXP(t)-1)*(1+2^-(EXP(q)-EXP(t)))
                             <= 2^(EXP(q)-EXP(t))
                             If EXP(q)-EXP(t)<0, <= 2^0 */
      /* We can get 0, but we can't round since q is inexact */
      if (MPFR_LIKELY (!MPFR_IS_ZERO (t)))
        {
          err = (mpfr_exp_t) p - 1 - MAX (MPFR_GET_EXP(q)-MPFR_GET_EXP(t), 0);
          res = MPFR_CAN_ROUND (t, err, MPFR_PREC (y), rnd_mode);
          if (MPFR_LIKELY (res != 0))  /* We can round! */
            {
              res = mpfr_set (y, t, rnd_mode);
              break;
            }
        }
      MPFR_ZIV_NEXT (loop, p);
      mpfr_set_prec (t, p);
      mpfr_set_prec (q, p);
    }
  MPFR_ZIV_FREE (loop);
  mpfr_clear (t);
  mpfr_clear (q);

  MPFR_SAVE_EXPO_FREE (expo);
  return mpfr_check_range (y, res, rnd_mode);
}

int
mpfr_cmp_q (mpfr_srcptr x, mpq_srcptr q)
{
  mpfr_t t;
  int res;
  mpfr_prec_t p;
  MPFR_SAVE_EXPO_DECL (expo);

  if (MPFR_UNLIKELY (mpq_denref (q) == 0))
    {
      /* q is an infinity or NaN */
      mpfr_init2 (t, 2);
      mpfr_set_q (t, q, MPFR_RNDN);
      res = mpfr_cmp (x, t);
      mpfr_clear (t);
      return res;
    }

  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
    return mpfr_cmp_si (x, mpq_sgn (q));

  MPFR_SAVE_EXPO_MARK (expo);

  /* x < a/b ? <=> x*b < a */
  MPFR_MPZ_SIZEINBASE2 (p, mpq_denref (q));
  mpfr_init2 (t, MPFR_PREC(x) + p);
  res = mpfr_mul_z (t, x, mpq_denref (q), MPFR_RNDN);
  MPFR_ASSERTD (res == 0);
  res = mpfr_cmp_z (t, mpq_numref (q));
  mpfr_clear (t);

  MPFR_SAVE_EXPO_FREE (expo);
  return res;
}

int
mpfr_cmp_f (mpfr_srcptr x, mpf_srcptr z)
{
  mpfr_t t;
  int res;
  MPFR_SAVE_EXPO_DECL (expo);

  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
    return mpfr_cmp_si (x, mpf_sgn (z));

  MPFR_SAVE_EXPO_MARK (expo);

  mpfr_init2 (t, MPFR_PREC_MIN + ABS(SIZ(z)) * GMP_NUMB_BITS );
  res = mpfr_set_f (t, z, MPFR_RNDN);
  MPFR_ASSERTD (res == 0);
  res = mpfr_cmp (x, t);
  mpfr_clear (t);

  MPFR_SAVE_EXPO_FREE (expo);
  return res;
}
