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/****************************************************************

 *

 * The author of this software is David M. Gay.

 *

 * Copyright (c) 1991 by AT&T.

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose without fee is hereby granted, provided that this entire notice

 * is included in all copies of any software which is or includes a copy

 * or modification of this software and in all copies of the supporting

 * documentation for such software.

 *

 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED

 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY

 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY

 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.

 *

 ***************************************************************/

/* Please send bug reports to

        David M. Gay

        AT&T Bell Laboratories, Room 2C-463

        600 Mountain Avenue

        Murray Hill, NJ 07974-2070

        U.S.A.

        dmg@research.att.com or research!dmg

 */

#include <_ansi.h>

#include <stdlib.h>

#include <reent.h>

#include <string.h>

#include "mprec.h"

static int

_DEFUN (quorem,

        (b, S),

        _Bigint * b _AND _Bigint * S)

{

  int n;

  __Long borrow, y;

  __ULong carry, q, ys;

  __ULong *bx, *bxe, *sx, *sxe;

#ifdef Pack_32

  __Long z;

  __ULong si, zs;

#endif

  n = S->_wds;

#ifdef DEBUG

  /*debug*/ if (b->_wds > n)

    /*debug*/ Bug ("oversize b in quorem");

#endif

  if (b->_wds < n)

    return 0;

  sx = S->_x;

  sxe = sx + --n;

  bx = b->_x;

  bxe = bx + n;

  q = *bxe / (*sxe + 1);        /* ensure q <= true quotient */

#ifdef DEBUG

  /*debug*/ if (q > 9)

    /*debug*/ Bug ("oversized quotient in quorem");

#endif

  if (q)

    {

      borrow = 0;

      carry = 0;

      do

        {

#ifdef Pack_32

          si = *sx++;

          ys = (si & 0xffff) * q + carry;

          zs = (si >> 16) * q + (ys >> 16);

          carry = zs >> 16;

          y = (*bx & 0xffff) - (ys & 0xffff) + borrow;

          borrow = y >> 16;

          Sign_Extend (borrow, y);

          z = (*bx >> 16) - (zs & 0xffff) + borrow;

          borrow = z >> 16;

          Sign_Extend (borrow, z);

          Storeinc (bx, z, y);

#else

          ys = *sx++ * q + carry;

          carry = ys >> 16;

          y = *bx - (ys & 0xffff) + borrow;

          borrow = y >> 16;

          Sign_Extend (borrow, y);

          *bx++ = y & 0xffff;

#endif

        }

      while (sx <= sxe);

      if (!*bxe)

        {

          bx = b->_x;

          while (--bxe > bx && !*bxe)

            --n;

          b->_wds = n;

        }

    }

  if (cmp (b, S) >= 0)

    {

      q++;

      borrow = 0;

      carry = 0;

      bx = b->_x;

      sx = S->_x;

      do

        {

#ifdef Pack_32

          si = *sx++;

          ys = (si & 0xffff) + carry;

          zs = (si >> 16) + (ys >> 16);

          carry = zs >> 16;

          y = (*bx & 0xffff) - (ys & 0xffff) + borrow;

          borrow = y >> 16;

          Sign_Extend (borrow, y);

          z = (*bx >> 16) - (zs & 0xffff) + borrow;

          borrow = z >> 16;

          Sign_Extend (borrow, z);

          Storeinc (bx, z, y);

#else

          ys = *sx++ + carry;

          carry = ys >> 16;

          y = *bx - (ys & 0xffff) + borrow;

          borrow = y >> 16;

          Sign_Extend (borrow, y);

          *bx++ = y & 0xffff;

#endif

        }

      while (sx <= sxe);

      bx = b->_x;

      bxe = bx + n;

      if (!*bxe)

        {

          while (--bxe > bx && !*bxe)

            --n;

          b->_wds = n;

        }

    }

  return q;

}

/* dtoa for IEEE arithmetic (dmg): convert double to ASCII string.

 *

 * Inspired by "How to Print Floating-Point Numbers Accurately" by

 * Guy L. Steele, Jr. and Jon L. White [Proc. ACM SIGPLAN '90, pp. 92-101].

 *

 * Modifications:

 *      1. Rather than iterating, we use a simple numeric overestimate

 *         to determine k = floor(log10(d)).  We scale relevant

 *         quantities using O(log2(k)) rather than O(k) multiplications.

 *      2. For some modes > 2 (corresponding to ecvt and fcvt), we don't

 *         try to generate digits strictly left to right.  Instead, we

 *         compute with fewer bits and propagate the carry if necessary

 *         when rounding the final digit up.  This is often faster.

 *      3. Under the assumption that input will be rounded nearest,

 *         mode 0 renders 1e23 as 1e23 rather than 9.999999999999999e22.

 *         That is, we allow equality in stopping tests when the

 *         round-nearest rule will give the same floating-point value

 *         as would satisfaction of the stopping test with strict

 *         inequality.

 *      4. We remove common factors of powers of 2 from relevant

 *         quantities.

 *      5. When converting floating-point integers less than 1e16,

 *         we use floating-point arithmetic rather than resorting

 *         to multiple-precision integers.

 *      6. When asked to produce fewer than 15 digits, we first try

 *         to get by with floating-point arithmetic; we resort to

 *         multiple-precision integer arithmetic only if we cannot

 *         guarantee that the floating-point calculation has given

 *         the correctly rounded result.  For k requested digits and

 *         "uniformly" distributed input, the probability is

 *         something like 10^(k-15) that we must resort to the long

 *         calculation.

 */

char *

_DEFUN (_dtoa_r,

        (ptr, _d, mode, ndigits, decpt, sign, rve),

        struct _reent *ptr _AND

        double _d _AND

        int mode _AND

        int ndigits _AND

        int *decpt _AND

        int *sign _AND

        char **rve)

{

  /*    Arguments ndigits, decpt, sign are similar to those

        of ecvt and fcvt; trailing zeros are suppressed from

        the returned string.  If not null, *rve is set to point

        to the end of the return value.  If d is +-Infinity or NaN,

        then *decpt is set to 9999.

        mode:

                        and rounded to nearest.

                1 ==> like 0, but with Steele & White stopping rule;

                        e.g. with IEEE P754 arithmetic , mode 0 gives

                        1e23 whereas mode 1 gives 9.999999999999999e22.

                2 ==> max(1,ndigits) significant digits.  This gives a

                        return value similar to that of ecvt, except

                        that trailing zeros are suppressed.

                3 ==> through ndigits past the decimal point.  This

                        gives a return value similar to that from fcvt,

                        except that trailing zeros are suppressed, and

                        ndigits can be negative.

                4-9 should give the same return values as 2-3, i.e.,

                        4 <= mode <= 9 ==> same return as mode

                        2 + (mode & 1).  These modes are mainly for

                        debugging; often they run slower but sometimes

                        faster than modes 2-3.

                4,5,8,9 ==> left-to-right digit generation.

                6-9 ==> don't try fast floating-point estimate

                        (if applicable).

                Values of mode other than 0-9 are treated as mode 0.

                Sufficient space is allocated to the return value

                to hold the suppressed trailing zeros.

        */

  int bbits, b2, b5, be, dig, i, ieps, ilim, ilim0, ilim1, j, j1, k, k0,

    k_check, leftright, m2, m5, s2, s5, spec_case, try_quick;

  union double_union d, d2, eps;

  __Long L;

#ifndef Sudden_Underflow

  int denorm;

  __ULong x;

#endif

  _Bigint *b, *b1, *delta, *mlo = NULL, *mhi, *S;

  double ds;

  char *s, *s0;

  d.d = _d;

  _REENT_CHECK_MP(ptr);

  if (_REENT_MP_RESULT(ptr))

    {

      _REENT_MP_RESULT(ptr)->_k = _REENT_MP_RESULT_K(ptr);

      _REENT_MP_RESULT(ptr)->_maxwds = 1 << _REENT_MP_RESULT_K(ptr);

      Bfree (ptr, _REENT_MP_RESULT(ptr));

      _REENT_MP_RESULT(ptr) = 0;

    }

  if (word0 (d) & Sign_bit)

    {

      /* set sign for everything, including 0's and NaNs */

      *sign = 1;

      word0 (d) &= ~Sign_bit;   /* clear sign bit */

    }

  else

    *sign = 0;

#if defined(IEEE_Arith) + defined(VAX)

#ifdef IEEE_Arith

  if ((word0 (d) & Exp_mask) == Exp_mask)

#else

  if (word0 (d) == 0x8000)

#endif

    {

      /* Infinity or NaN */

      *decpt = 9999;

      s =

#ifdef IEEE_Arith

        !word1 (d) && !(word0 (d) & 0xfffff) ? "Infinity" :

#endif

        "NaN";

      if (rve)

        *rve =

#ifdef IEEE_Arith

          s[3] ? s + 8 :

#endif

          s + 3;

      return s;

    }

#endif

#ifdef IBM

  d.d += 0;                      /* normalize */

#endif

  if (!d.d)

    {

      *decpt = 1;

      s = "0";

      if (rve)

        *rve = s + 1;

      return s;

    }

  b = d2b (ptr, d.d, &be, &bbits);

#ifdef Sudden_Underflow

  i = (int) (word0 (d) >> Exp_shift1 & (Exp_mask >> Exp_shift1));

#else

  if ((i = (int) (word0 (d) >> Exp_shift1 & (Exp_mask >> Exp_shift1))) != 0)

    {

#endif

      d2.d = d.d;

      word0 (d2) &= Frac_mask1;

      word0 (d2) |= Exp_11;

#ifdef IBM

      if (j = 11 - hi0bits (word0 (d2) & Frac_mask))

        d2.d /= 1 << j;

#endif

      /* log(x) ~=~ log(1.5) + (x-1.5)/1.5

                 * log10(x)      =  log(x) / log(10)

                 *              ~=~ log(1.5)/log(10) + (x-1.5)/(1.5*log(10))

                 * log10(d) = (i-Bias)*log(2)/log(10) + log10(d2)

                 *

                 * This suggests computing an approximation k to log10(d) by

                 *

                 * k = (i - Bias)*0.301029995663981

                 *      + ( (d2-1.5)*0.289529654602168 + 0.176091259055681 );

                 *

                 * We want k to be too large rather than too small.

                 * The error in the first-order Taylor series approximation

                 * is in our favor, so we just round up the constant enough

                 * to compensate for any error in the multiplication of

                 * (i - Bias) by 0.301029995663981; since |i - Bias| <= 1077,

                 * and 1077 * 0.30103 * 2^-52 ~=~ 7.2e-14,

                 * adding 1e-13 to the constant term more than suffices.

                 * Hence we adjust the constant term to 0.1760912590558.

                 * (We could get a more accurate k by invoking log10,

                 *  but this is probably not worthwhile.)

                 */

      i -= Bias;

#ifdef IBM

      i <<= 2;

      i += j;

#endif

#ifndef Sudden_Underflow

      denorm = 0;

    }

  else

    {

      /* d is denormalized */

      i = bbits + be + (Bias + (P - 1) - 1);

#if defined (_DOUBLE_IS_32BITS)

      x = word0 (d) << (32 - i);

#else

      x = (i > 32) ? (word0 (d) << (64 - i)) | (word1 (d) >> (i - 32))

       : (word1 (d) << (32 - i));

#endif

      d2.d = x;

      word0 (d2) -= 31 * Exp_msk1;      /* adjust exponent */

      i -= (Bias + (P - 1) - 1) + 1;

      denorm = 1;

    }

#endif

#if defined (_DOUBLE_IS_32BITS)

  ds = (d2.d - 1.5) * 0.289529651 + 0.176091269 + i * 0.30103001;

#else

  ds = (d2.d - 1.5) * 0.289529654602168 + 0.1760912590558 + i * 0.301029995663981;

#endif

  k = (int) ds;

  if (ds < 0. && ds != k)

    k--;                        /* want k = floor(ds) */

  k_check = 1;

  if (k >= 0 && k <= Ten_pmax)

    {

      if (d.d < tens[k])

        k--;

      k_check = 0;

    }

  j = bbits - i - 1;

  if (j >= 0)

    {

      b2 = 0;

      s2 = j;

    }

  else

    {

      b2 = -j;

      s2 = 0;

    }

  if (k >= 0)

    {

      b5 = 0;

      s5 = k;

      s2 += k;

    }

  else

    {

      b2 -= k;

      b5 = -k;

      s5 = 0;

    }

  if (mode < 0 || mode > 9)

    mode = 0;

  try_quick = 1;

  if (mode > 5)

    {

      mode -= 4;

      try_quick = 0;

    }

  leftright = 1;

  ilim = ilim1 = -1;

  switch (mode)

    {

    case 0:

    case 1:

      i = 18;

      ndigits = 0;

      break;

    case 2:

      leftright = 0;

      /* no break */

    case 4:

      if (ndigits <= 0)

        ndigits = 1;

      ilim = ilim1 = i = ndigits;

      break;

    case 3:

      leftright = 0;

      /* no break */

    case 5:

      i = ndigits + k + 1;

      ilim = i;

      ilim1 = i - 1;

      if (i <= 0)

        i = 1;

    }

  j = sizeof (__ULong);

  for (_REENT_MP_RESULT_K(ptr) = 0; sizeof (_Bigint) - sizeof (__ULong) + j <= i;

       j <<= 1)

    _REENT_MP_RESULT_K(ptr)++;

  _REENT_MP_RESULT(ptr) = Balloc (ptr, _REENT_MP_RESULT_K(ptr));

  s = s0 = (char *) _REENT_MP_RESULT(ptr);

  if (ilim >= 0 && ilim <= Quick_max && try_quick)

    {

      /* Try to get by with floating-point arithmetic. */

      i = 0;

      d2.d = d.d;

      k0 = k;

      ilim0 = ilim;

      ieps = 2;                 /* conservative */

      if (k > 0)

        {

          ds = tens[k & 0xf];

          j = k >> 4;

          if (j & Bletch)

            {

              /* prevent overflows */

              j &= Bletch - 1;

              d.d /= bigtens[n_bigtens - 1];

              ieps++;

            }

          for (; j; j >>= 1, i++)

            if (j & 1)

              {

                ieps++;

                ds *= bigtens[i];

              }

          d.d /= ds;

        }

      else if ((j1 = -k) != 0)

        {

          d.d *= tens[j1 & 0xf];

          for (j = j1 >> 4; j; j >>= 1, i++)

            if (j & 1)

              {

                ieps++;

                d.d *= bigtens[i];

              }

        }

      if (k_check && d.d < 1. && ilim > 0)

        {

          if (ilim1 <= 0)

            goto fast_failed;

          ilim = ilim1;

          k--;

          d.d *= 10.;

          ieps++;

        }

      eps.d = ieps * d.d + 7.;

      word0 (eps) -= (P - 1) * Exp_msk1;

      if (ilim == 0)

        {

          S = mhi = 0;

          d.d -= 5.;

          if (d.d > eps.d)

            goto one_digit;

          if (d.d < -eps.d)

            goto no_digits;

          goto fast_failed;

        }

#ifndef No_leftright

      if (leftright)

        {

          /* Use Steele & White method of only

           * generating digits needed.

           */

          eps.d = 0.5 / tens[ilim - 1] - eps.d;

          for (i = 0;;)

            {

              L = d.d;

              d.d -= L;

              *s++ = '0' + (int) L;

              if (d.d < eps.d)

                goto ret1;

              if (1. - d.d < eps.d)

                goto bump_up;

              if (++i >= ilim)

                break;

              eps.d *= 10.;

              d.d *= 10.;

            }

        }

      else

        {

#endif

          /* Generate ilim digits, then fix them up. */

          eps.d *= tens[ilim - 1];

          for (i = 1;; i++, d.d *= 10.)

            {

              L = d.d;

              d.d -= L;

              *s++ = '0' + (int) L;

              if (i == ilim)

                {

                  if (d.d > 0.5 + eps.d)

                    goto bump_up;

                  else if (d.d < 0.5 - eps.d)

                    {

                      while (*--s == '0');

                      s++;

                      goto ret1;

                    }

                  break;

                }

            }

#ifndef No_leftright

        }

#endif

    fast_failed:

      s = s0;

      d.d = d2.d;

      k = k0;

      ilim = ilim0;

    }

  /* Do we have a "small" integer? */

  if (be >= 0 && k <= Int_max)

    {

      /* Yes. */

      ds = tens[k];

      if (ndigits < 0 && ilim <= 0)

        {

          S = mhi = 0;

          if (ilim < 0 || d.d <= 5 * ds)

            goto no_digits;

          goto one_digit;

        }

      for (i = 1;; i++)

        {

          L = d.d / ds;

          d.d -= L * ds;

#ifdef Check_FLT_ROUNDS

          /* If FLT_ROUNDS == 2, L will usually be high by 1 */

          if (d.d < 0)

            {

              L--;

              d.d += ds;

            }

#endif

          *s++ = '0' + (int) L;

          if (i == ilim)

            {

              d.d += d.d;

             if ((d.d > ds) || ((d.d == ds) && (L & 1)))

                {

                bump_up:

                  while (*--s == '9')

                    if (s == s0)

                      {

                        k++;

                        *s = '0';

                        break;

                      }

                  ++*s++;

                }

              break;

            }

          if (!(d.d *= 10.))

            break;

        }

      goto ret1;

    }

  m2 = b2;

  m5 = b5;

  mhi = mlo = 0;

  if (leftright)

    {

      if (mode < 2)

        {

          i =

#ifndef Sudden_Underflow

            denorm ? be + (Bias + (P - 1) - 1 + 1) :

#endif

#ifdef IBM

            1 + 4 * P - 3 - bbits + ((bbits + be - 1) & 3);

#else

            1 + P - bbits;

#endif

        }

      else

        {

          j = ilim - 1;

          if (m5 >= j)

            m5 -= j;

          else

            {

              s5 += j -= m5;

              b5 += j;

              m5 = 0;

            }

          if ((i = ilim) < 0)

            {

              m2 -= i;

              i = 0;

            }

        }

      b2 += i;

      s2 += i;

      mhi = i2b (ptr, 1);

    }

  if (m2 > 0 && s2 > 0)

    {

      i = m2 < s2 ? m2 : s2;

      b2 -= i;

      m2 -= i;

      s2 -= i;

    }

  if (b5 > 0)

    {

      if (leftright)

        {

          if (m5 > 0)

            {

              mhi = pow5mult (ptr, mhi, m5);

              b1 = mult (ptr, mhi, b);

              Bfree (ptr, b);

              b = b1;

            }

         if ((j = b5 - m5) != 0)

            b = pow5mult (ptr, b, j);

        }

      else

        b = pow5mult (ptr, b, b5);

    }

  S = i2b (ptr, 1);

  if (s5 > 0)

    S = pow5mult (ptr, S, s5);

  /* Check for special case that d is a normalized power of 2. */

  spec_case = 0;

  if (mode < 2)

    {

      if (!word1 (d) && !(word0 (d) & Bndry_mask)

#ifndef Sudden_Underflow

          && word0 (d) & Exp_mask

#endif

        )

        {