gcc/libgfortran/io/write_float.def

/* Copyright (C) 2007 Free Software Foundation, Inc.
   Contributed by Andy Vaught
   Write float code factoring to this file by Jerry DeLisle   

This file is part of the GNU Fortran 95 runtime library (libgfortran).

Libgfortran is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

In addition to the permissions in the GNU General Public License, the
Free Software Foundation gives you unlimited permission to link the
compiled version of this file into combinations with other programs,
and to distribute those combinations without any restriction coming
from the use of this file.  (The General Public License restrictions
do apply in other respects; for example, they cover modification of
the file, and distribution when not linked into a combine
executable.)

Libgfortran 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 a copy of the GNU General Public License
along with Libgfortran; see the file COPYING.  If not, write to
the Free Software Foundation, 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

#include "config.h"

typedef enum
{ SIGN_NONE, SIGN_MINUS, SIGN_PLUS }
sign_t;

/* Given a flag that indicates if a value is negative or not, return a
   sign_t that gives the sign that we need to produce.  */

static sign_t
calculate_sign (st_parameter_dt *dtp, int negative_flag)
{
  sign_t s = SIGN_NONE;

  if (negative_flag)
    s = SIGN_MINUS;
  else
    switch (dtp->u.p.sign_status)
      {
      case SIGN_SP:
	s = SIGN_PLUS;
	break;
      case SIGN_SS:
	s = SIGN_NONE;
	break;
      case SIGN_S:
	s = options.optional_plus ? SIGN_PLUS : SIGN_NONE;
	break;
      }

  return s;
}


/* Output a real number according to its format which is FMT_G free.  */

static void
output_float (st_parameter_dt *dtp, const fnode *f, char *buffer, size_t size, 
	      int sign_bit, bool zero_flag, int ndigits, int edigits)
{
  char *out;
  char *digits;
  int e;
  char expchar;
  format_token ft;
  int w;
  int d;
  /* Number of digits before the decimal point.  */
  int nbefore;
  /* Number of zeros after the decimal point.  */
  int nzero;
  /* Number of digits after the decimal point.  */
  int nafter;
  /* Number of zeros after the decimal point, whatever the precision.  */
  int nzero_real;
  int leadzero;
  int nblanks;
  int i;
  sign_t sign;

  ft = f->format;
  w = f->u.real.w;
  d = f->u.real.d;

  nzero_real = -1;

  /* We should always know the field width and precision.  */
  if (d < 0)
    internal_error (&dtp->common, "Unspecified precision");

  /* Use sprintf to print the number in the format +D.DDDDe+ddd
     For an N digit exponent, this gives us (MIN_FIELD_WIDTH-5)-N digits
     after the decimal point, plus another one before the decimal point.  */

  sign = calculate_sign (dtp, sign_bit);

  /* #   The result will always contain a decimal point, even if no
   *     digits follow it
   *
   * -   The converted value is to be left adjusted on the field boundary
   *
   * +   A sign (+ or -) always be placed before a number
   *
   * MIN_FIELD_WIDTH  minimum field width
   *
   * *   (ndigits-1) is used as the precision
   *
   *   e format: [-]d.ddde±dd where there is one digit before the
   *   decimal-point character and the number of digits after it is
   *   equal to the precision. The exponent always contains at least two
   *   digits; if the value is zero, the exponent is 00.
   */

  /* Check the given string has punctuation in the correct places.  */
  if (d != 0 && (buffer[2] != '.' || buffer[ndigits + 2] != 'e'))
      internal_error (&dtp->common, "printf is broken");

  /* Read the exponent back in.  */
  e = atoi (&buffer[ndigits + 3]) + 1;

  /* Make sure zero comes out as 0.0e0.   */
  if (zero_flag)
    {
      e = 0;
      if (compile_options.sign_zero == 1)
	sign = calculate_sign (dtp, sign_bit);
      else
	sign = calculate_sign (dtp, 0);
    }

  /* Normalize the fractional component.  */
  buffer[2] = buffer[1];
  digits = &buffer[2];

  /* Figure out where to place the decimal point.  */
  switch (ft)
    {
    case FMT_F:
      nbefore = e + dtp->u.p.scale_factor;
      if (nbefore < 0)
	{
	  nzero = -nbefore;
          nzero_real = nzero;
	  if (nzero > d)
	    nzero = d;
	  nafter = d - nzero;
	  nbefore = 0;
	}
      else
	{
	  nzero = 0;
	  nafter = d;
	}
      expchar = 0;
      break;

    case FMT_E:
    case FMT_D:
      i = dtp->u.p.scale_factor;
      if (!zero_flag)
	e -= i;
      if (i < 0)
	{
	  nbefore = 0;
	  nzero = -i;
	  nafter = d + i;
	}
      else if (i > 0)
	{
	  nbefore = i;
	  nzero = 0;
	  nafter = (d - i) + 1;
	}
      else /* i == 0 */
	{
	  nbefore = 0;
	  nzero = 0;
	  nafter = d;
	}

      if (ft == FMT_E)
	expchar = 'E';
      else
	expchar = 'D';
      break;

    case FMT_EN:
      /* The exponent must be a multiple of three, with 1-3 digits before
	 the decimal point.  */
      if (!zero_flag)
        e--;
      if (e >= 0)
	nbefore = e % 3;
      else
	{
	  nbefore = (-e) % 3;
	  if (nbefore != 0)
	    nbefore = 3 - nbefore;
	}
      e -= nbefore;
      nbefore++;
      nzero = 0;
      nafter = d;
      expchar = 'E';
      break;

    case FMT_ES:
      if (!zero_flag)
        e--;
      nbefore = 1;
      nzero = 0;
      nafter = d;
      expchar = 'E';
      break;

    default:
      /* Should never happen.  */
      internal_error (&dtp->common, "Unexpected format token");
    }

  /* Round the value.  */
  if (nbefore + nafter == 0)
    {
      ndigits = 0;
      if (nzero_real == d && digits[0] >= '5')
        {
          /* We rounded to zero but shouldn't have */
          nzero--;
          nafter = 1;
          digits[0] = '1';
          ndigits = 1;
        }
    }
  else if (nbefore + nafter < ndigits)
    {
      ndigits = nbefore + nafter;
      i = ndigits;
      if (digits[i] >= '5')
	{
	  /* Propagate the carry.  */
	  for (i--; i >= 0; i--)
	    {
	      if (digits[i] != '9')
		{
		  digits[i]++;
		  break;
		}
	      digits[i] = '0';
	    }

	  if (i < 0)
	    {
	      /* The carry overflowed.  Fortunately we have some spare space
		 at the start of the buffer.  We may discard some digits, but
		 this is ok because we already know they are zero.  */
	      digits--;
	      digits[0] = '1';
	      if (ft == FMT_F)
		{
		  if (nzero > 0)
		    {
		      nzero--;
		      nafter++;
		    }
		  else
		    nbefore++;
		}
	      else if (ft == FMT_EN)
		{
		  nbefore++;
		  if (nbefore == 4)
		    {
		      nbefore = 1;
		      e += 3;
		    }
		}
	      else
		e++;
	    }
	}
    }

  /* Calculate the format of the exponent field.  */
  if (expchar)
    {
      edigits = 1;
      for (i = abs (e); i >= 10; i /= 10)
	edigits++;

      if (f->u.real.e < 0)
	{
	  /* Width not specified.  Must be no more than 3 digits.  */
	  if (e > 999 || e < -999)
	    edigits = -1;
	  else
	    {
	      edigits = 4;
	      if (e > 99 || e < -99)
		expchar = ' ';
	    }
	}
      else
	{
	  /* Exponent width specified, check it is wide enough.  */
	  if (edigits > f->u.real.e)
	    edigits = -1;
	  else
	    edigits = f->u.real.e + 2;
	}
    }
  else
    edigits = 0;

  /* Pick a field size if none was specified.  */
  if (w <= 0)
    w = nbefore + nzero + nafter + (sign != SIGN_NONE ? 2 : 1);

  /* Create the ouput buffer.  */
  out = write_block (dtp, w);
  if (out == NULL)
    return;

  /* Zero values always output as positive, even if the value was negative
     before rounding.  */
  for (i = 0; i < ndigits; i++)
    {
      if (digits[i] != '0')
	break;
    }
  if (i == ndigits)
    {
      /* The output is zero, so set the sign according to the sign bit unless
	 -fno-sign-zero was specified.  */
      if (compile_options.sign_zero == 1)
        sign = calculate_sign (dtp, sign_bit);
      else
	sign = calculate_sign (dtp, 0);
    }

  /* Work out how much padding is needed.  */
  nblanks = w - (nbefore + nzero + nafter + edigits + 1);
  if (sign != SIGN_NONE)
    nblanks--;

  /* Check the value fits in the specified field width.  */
  if (nblanks < 0 || edigits == -1)
    {
      star_fill (out, w);
      return;
    }

  /* See if we have space for a zero before the decimal point.  */
  if (nbefore == 0 && nblanks > 0)
    {
      leadzero = 1;
      nblanks--;
    }
  else
    leadzero = 0;

  /* Pad to full field width.  */

  if ( ( nblanks > 0 ) && !dtp->u.p.no_leading_blank)
    {
      memset (out, ' ', nblanks);
      out += nblanks;
    }

  /* Output the initial sign (if any).  */
  if (sign == SIGN_PLUS)
    *(out++) = '+';
  else if (sign == SIGN_MINUS)
    *(out++) = '-';

  /* Output an optional leading zero.  */
  if (leadzero)
    *(out++) = '0';

  /* Output the part before the decimal point, padding with zeros.  */
  if (nbefore > 0)
    {
      if (nbefore > ndigits)
	{
	  i = ndigits;
	  memcpy (out, digits, i);
	  ndigits = 0;
	  while (i < nbefore)
	    out[i++] = '0';
	}
      else
	{
	  i = nbefore;
	  memcpy (out, digits, i);
	  ndigits -= i;
	}

      digits += i;
      out += nbefore;
    }
  /* Output the decimal point.  */
  *(out++) = '.';

  /* Output leading zeros after the decimal point.  */
  if (nzero > 0)
    {
      for (i = 0; i < nzero; i++)
	*(out++) = '0';
    }

  /* Output digits after the decimal point, padding with zeros.  */
  if (nafter > 0)
    {
      if (nafter > ndigits)
	i = ndigits;
      else
	i = nafter;

      memcpy (out, digits, i);
      while (i < nafter)
	out[i++] = '0';

      digits += i;
      ndigits -= i;
      out += nafter;
    }

  /* Output the exponent.  */
  if (expchar)
    {
      if (expchar != ' ')
	{
	  *(out++) = expchar;
	  edigits--;
	}
#if HAVE_SNPRINTF
      snprintf (buffer, size, "%+0*d", edigits, e);
#else
      sprintf (buffer, "%+0*d", edigits, e);
#endif
      memcpy (out, buffer, edigits);
    }
  if (dtp->u.p.no_leading_blank)
    {
      out += edigits;
      memset( out , ' ' , nblanks );
      dtp->u.p.no_leading_blank = 0;
    }
#undef STR
#undef STR1
#undef MIN_FIELD_WIDTH
}


/* Write "Infinite" or "Nan" as appropriate for the given format.  */

static void
write_infnan (st_parameter_dt *dtp, const fnode *f, int isnan_flag, int sign_bit)
{
  char * p, fin;
  int nb = 0;

  if (f->format != FMT_B && f->format != FMT_O && f->format != FMT_Z)
    {
	  nb =  f->u.real.w;
	  
	  /* If the field width is zero, the processor must select a width 
	     not zero.  4 is chosen to allow output of '-Inf' or '+Inf' */
	     
	  if (nb == 0) nb = 4;
	  p = write_block (dtp, nb);
          if (p == NULL)
            return;
	  if (nb < 3)
	    {
	      memset (p, '*',nb);
	      return;
	    }

	  memset(p, ' ', nb);
	  if (!isnan_flag)
	    {
	      if (sign_bit)
	        {
	        
	          /* If the sign is negative and the width is 3, there is
	             insufficient room to output '-Inf', so output asterisks */
	             
	          if (nb == 3)
	            {
	              memset (p, '*',nb);
	              return;
	            }
	            
	          /* The negative sign is mandatory */
	            
	          fin = '-';
		}    
	      else
	      
	          /* The positive sign is optional, but we output it for
	             consistency */
		  fin = '+';

	      if (nb > 8)
	      
	        /* We have room, so output 'Infinity' */
		memcpy(p + nb - 8, "Infinity", 8);
	      else
	      
	        /* For the case of width equals 8, there is not enough room
	           for the sign and 'Infinity' so we go with 'Inf' */
		memcpy(p + nb - 3, "Inf", 3);

	      if (nb < 9 && nb > 3)
		p[nb - 4] = fin;  /* Put the sign in front of Inf */
	      else if (nb > 8)
		p[nb - 9] = fin;  /* Put the sign in front of Infinity */
	    }
	  else
	    memcpy(p + nb - 3, "NaN", 3);
	  return;
	}
    }


/* Returns the value of 10**d.  */

#define CALCULATE_EXP(x) \
inline static GFC_REAL_ ## x \
calculate_exp_ ## x  (int d)\
{\
  int i;\
  GFC_REAL_ ## x r = 1.0;\
  for (i = 0; i< (d >= 0 ? d : -d); i++)\
    r *= 10;\
  r = (d >= 0) ? r : 1.0 / r;\
  return r;\
}

CALCULATE_EXP(4)

CALCULATE_EXP(8)

#ifdef HAVE_GFC_REAL_10
CALCULATE_EXP(10)
#endif

#ifdef HAVE_GFC_REAL_16
CALCULATE_EXP(16)
#endif
#undef CALCULATE_EXP

/* Generate corresponding I/O format for FMT_G and output.
   The rules to translate FMT_G to FMT_E or FMT_F from DEC fortran
   LRM (table 11-2, Chapter 11, "I/O Formatting", P11-25) is:

   Data Magnitude                              Equivalent Conversion
   0< m < 0.1-0.5*10**(-d-1)                   Ew.d[Ee]
   m = 0                                       F(w-n).(d-1), n' '
   0.1-0.5*10**(-d-1)<= m < 1-0.5*10**(-d)     F(w-n).d, n' '
   1-0.5*10**(-d)<= m < 10-0.5*10**(-d+1)      F(w-n).(d-1), n' '
   10-0.5*10**(-d+1)<= m < 100-0.5*10**(-d+2)  F(w-n).(d-2), n' '
   ................                           ..........
   10**(d-1)-0.5*10**(-1)<= m <10**d-0.5       F(w-n).0,n(' ')
   m >= 10**d-0.5                              Ew.d[Ee]

   notes: for Gw.d ,  n' ' means 4 blanks
          for Gw.dEe, n' ' means e+2 blanks  */

#define OUTPUT_FLOAT_FMT_G(x) \
static void \
output_float_FMT_G_ ## x (st_parameter_dt *dtp, const fnode *f, \
		      GFC_REAL_ ## x m, char *buffer, size_t size, \
		      int sign_bit, bool zero_flag, int ndigits, int edigits) \
{ \
  int e = f->u.real.e;\
  int d = f->u.real.d;\
  int w = f->u.real.w;\
  fnode *newf;\
  GFC_REAL_ ## x exp_d;\
  int low, high, mid;\
  int ubound, lbound;\
  char *p;\
  int save_scale_factor, nb = 0;\
\
  save_scale_factor = dtp->u.p.scale_factor;\
  newf = get_mem (sizeof (fnode));\
\
  exp_d = calculate_exp_ ## x (d);\
  if ((m > 0.0 && m < 0.1 - 0.05 / exp_d) || (m >= exp_d - 0.5 ) ||\
      ((m == 0.0) && !(compile_options.allow_std & GFC_STD_F2003)))\
    { \
      newf->format = FMT_E;\
      newf->u.real.w = w;\
      newf->u.real.d = d;\
      newf->u.real.e = e;\
      nb = 0;\
      goto finish;\
    }\
\
  mid = 0;\
  low = 0;\
  high = d + 1;\
  lbound = 0;\
  ubound = d + 1;\
\
  while (low <= high)\
    { \
      GFC_REAL_ ## x temp;\
      mid = (low + high) / 2;\
\
      temp = 0.1 * calculate_exp_ ## x (mid) - 0.5\
	     * calculate_exp_ ## x (mid - d - 1);\
\
      if (m < temp)\
        { \
          ubound = mid;\
          if (ubound == lbound + 1)\
            break;\
          high = mid - 1;\
        }\
      else if (m > temp)\
        { \
          lbound = mid;\
          if (ubound == lbound + 1)\
            { \
              mid ++;\
              break;\
            }\
          low = mid + 1;\
        }\
      else\
        break;\
    }\
\
  if (e < 0)\
    nb = 4;\
  else\
    nb = e + 2;\
\
  newf->format = FMT_F;\
  newf->u.real.w = f->u.real.w - nb;\
\
  if (m == 0.0)\
    newf->u.real.d = d - 1;\
  else\
    newf->u.real.d = - (mid - d - 1);\
\
  dtp->u.p.scale_factor = 0;\
\
 finish:\
  output_float (dtp, newf, buffer, size, sign_bit, zero_flag, ndigits, \
		edigits);\
  dtp->u.p.scale_factor = save_scale_factor;\
\
  free_mem(newf);\
\
  if (nb > 0)\
    { \
      p = write_block (dtp, nb);\
      if (p == NULL)\
	return;\
      memset (p, ' ', nb);\
    }\
}\

OUTPUT_FLOAT_FMT_G(4)

OUTPUT_FLOAT_FMT_G(8)

#ifdef HAVE_GFC_REAL_10
OUTPUT_FLOAT_FMT_G(10)
#endif

#ifdef HAVE_GFC_REAL_16
OUTPUT_FLOAT_FMT_G(16)
#endif

#undef OUTPUT_FLOAT_FMT_G

/* Define a macro to build code for write_float.  */

#ifdef HAVE_SNPRINTF

#define DTOA \
snprintf (buffer, size, "%+-#" STR(MIN_FIELD_WIDTH) ".*" \
	  "e", ndigits - 1, tmp);

#define DTOAL \
snprintf (buffer, size, "%+-#" STR(MIN_FIELD_WIDTH) ".*" \
	  "Le", ndigits - 1, tmp);

#else

#define DTOA \
sprintf (buffer, "%+-#" STR(MIN_FIELD_WIDTH) ".*" \
	 "e", ndigits - 1, tmp);

#define DTOAL \
sprintf (buffer, "%+-#" STR(MIN_FIELD_WIDTH) ".*" \
	 "Le", ndigits - 1, tmp);

#endif

#define WRITE_FLOAT(x,y)\
{\
	GFC_REAL_ ## x tmp;\
	tmp = * (GFC_REAL_ ## x *)source;\
	sign_bit = signbit (tmp);\
	if (!isfinite (tmp))\
	  { \
	    write_infnan (dtp, f, isnan (tmp), sign_bit);\
	    return;\
	  }\
	tmp = sign_bit ? -tmp : tmp;\
	if (f->u.real.d == 0 && f->format == FMT_F)\
	  {\
	    if (tmp < 0.5)\
	      tmp = 0.0;\
	    else if (tmp < 1.0)\
	      tmp = tmp + 0.5;\
	  }\
	zero_flag = (tmp == 0.0);\
\
	DTOA ## y\
\
	if (f->format != FMT_G)\
	  output_float (dtp, f, buffer, size, sign_bit, zero_flag, ndigits, \
			edigits);\
	else \
	  output_float_FMT_G_ ## x (dtp, f, tmp, buffer, size, sign_bit, \
				    zero_flag, ndigits, edigits);\
}\

/* Output a real number according to its format.  */

static void
write_float (st_parameter_dt *dtp, const fnode *f, const char *source, int len)
{

#if defined(HAVE_GFC_REAL_16) && __LDBL_DIG__ > 18
# define MIN_FIELD_WIDTH 46
#else
# define MIN_FIELD_WIDTH 31
#endif
#define STR(x) STR1(x)
#define STR1(x) #x

  /* This must be large enough to accurately hold any value.  */
  char buffer[MIN_FIELD_WIDTH+1];
  int sign_bit, ndigits, edigits;
  bool zero_flag;
  size_t size;

  size = MIN_FIELD_WIDTH+1;

  /* printf pads blanks for us on the exponent so we just need it big enough
     to handle the largest number of exponent digits expected.  */
  edigits=4;

  if (f->format == FMT_F || f->format == FMT_EN || f->format == FMT_G 
      || ((f->format == FMT_D || f->format == FMT_E)
      && dtp->u.p.scale_factor != 0))
    {
      /* Always convert at full precision to avoid double rounding.  */
      ndigits = MIN_FIELD_WIDTH - 4 - edigits;
    }
  else
    {
      /* The number of digits is known, so let printf do the rounding.  */
      if (f->format == FMT_ES)
	ndigits = f->u.real.d + 1;
      else
	ndigits = f->u.real.d;
      if (ndigits > MIN_FIELD_WIDTH - 4 - edigits)
	ndigits = MIN_FIELD_WIDTH - 4 - edigits;
    }

  switch (len)
    {
    case 4:
      WRITE_FLOAT(4,)
      break;

    case 8:
      WRITE_FLOAT(8,)
      break;

#ifdef HAVE_GFC_REAL_10
    case 10:
      WRITE_FLOAT(10,L)
      break;
#endif
#ifdef HAVE_GFC_REAL_16
    case 16:
      WRITE_FLOAT(16,L)
      break;
#endif
    default:
      internal_error (NULL, "bad real kind");
    }
}