read.c   [plain text]

/* Copyright (C) 2002-2003 Free Software Foundation, Inc.
   Contributed by Andy Vaught

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, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


#include "config.h"
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include "libgfortran.h"
#include "io.h"

/* read.c -- Deal with formatted reads */

/* set_integer()-- All of the integer assignments come here to
 * actually place the value into memory.  */

void
set_integer (void *dest, int64_t value, int length)
{
  switch (length)
    {
    case 8:
      *((int64_t *) dest) = value;
      break;
    case 4:
      *((int32_t *) dest) = value;
      break;
    case 2:
      *((int16_t *) dest) = value;
      break;
    case 1:
      *((int8_t *) dest) = value;
      break;
    default:
      internal_error ("Bad integer kind");
    }
}


/* max_value()-- Given a length (kind), return the maximum signed or
 * unsigned value */

uint64_t
max_value (int length, int signed_flag)
{
  uint64_t value;

  switch (length)
    {
    case 8:
      value = signed_flag ? 0x7fffffffffffffff : 0xffffffffffffffff;
      break;
    case 4:
      value = signed_flag ? 0x7fffffff : 0xffffffff;
      break;
    case 2:
      value = signed_flag ? 0x7fff : 0xffff;
      break;
    case 1:
      value = signed_flag ? 0x7f : 0xff;
      break;
    default:
      internal_error ("Bad integer kind");
    }

  return value;
}


/* convert_real()-- Convert a character representation of a floating
 * point number to the machine number.  Returns nonzero if there is a
 * range problem during conversion.  TODO: handle not-a-numbers and
 * infinities.  */

int
convert_real (void *dest, const char *buffer, int length)
{
  errno = 0;

  switch (length)
    {
    case 4:
      *((float *) dest) =
#if defined(HAVE_STRTOF)
	strtof (buffer, NULL);
#else
	(float) strtod (buffer, NULL);
#endif
      break;
    case 8:
      *((double *) dest) = strtod (buffer, NULL);
      break;
    default:
      internal_error ("Unsupported real kind during IO");
    }

  if (errno != 0)
    {
      generate_error (ERROR_READ_VALUE,
		      "Range error during floating point read");
      return 1;
    }

  return 0;
}


/* read_l()-- Read a logical value */

void
read_l (fnode * f, char *dest, int length)
{
  char *p;
  int w;

  w = f->u.w;
  p = read_block (&w);
  if (p == NULL)
    return;

  while (*p == ' ')
    {
      if (--w == 0)
	goto bad;
      p++;
    }

  if (*p == '.')
    {
      if (--w == 0)
	goto bad;
      p++;
    }

  switch (*p)
    {
    case 't':
    case 'T':
      set_integer (dest, 1, length);
      break;
    case 'f':
    case 'F':
      set_integer (dest, 0, length);
      break;
    default:
    bad:
      generate_error (ERROR_READ_VALUE, "Bad value on logical read");
      break;
    }
}


/* read_a()-- Read a character record.  This one is pretty easy. */

void
read_a (fnode * f, char *p, int length)
{
  char *source;
  int w, m, n;

  w = f->u.w;
  if (w == -1) /* '(A)' edit descriptor  */
    w = length;

  source = read_block (&w);
  if (source == NULL)
    return;
  if (w > length)
     source += (w - length);

  m = (w > length) ? length : w;
  memcpy (p, source, m);

  n = length - w;
  if (n > 0)
    memset (p + m, ' ', n);
}


/* eat_leading_spaces()-- Given a character pointer and a width,
 * ignore the leading spaces.  */

static char *
eat_leading_spaces (int *width, char *p)
{
  for (;;)
    {
      if (*width == 0 || *p != ' ')
	break;

      (*width)--;
      p++;
    }

  return p;
}


static char
next_char (char **p, int *w)
{
  char c, *q;

  if (*w == 0)
    return '\0';

  q = *p;
  c = *q++;
  *p = q;

  (*w)--;

  if (c != ' ')
    return c;
  if (g.blank_status == BLANK_ZERO)
    return '0';

  /* At this point, the rest of the field has to be trailing blanks */

  while (*w > 0)
    {
      if (*q++ != ' ')
	return '?';
      (*w)--;
    }

  *p = q;
  return '\0';
}


/* read_decimal()-- Read a decimal integer value.  The values here are
 * signed values. */

void
read_decimal (fnode * f, char *dest, int length)
{
  unsigned value, maxv, maxv_10;
  int v, w, negative;
  char c, *p;

  w = f->u.w;
  p = read_block (&w);
  if (p == NULL)
    return;

  p = eat_leading_spaces (&w, p);
  if (w == 0)
    {
      set_integer (dest, 0, length);
      return;
    }

  maxv = max_value (length, 1);
  maxv_10 = maxv / 10;

  negative = 0;
  value = 0;

  switch (*p)
    {
    case '-':
      negative = 1;
      /* Fall through */

    case '+':
      p++;
      if (--w == 0)
	goto bad;
      /* Fall through */

    default:
      break;
    }

  /* At this point we have a digit-string */
  value = 0;

  for (;;)
    {
      c = next_char (&p, &w);
      if (c == '\0')
	break;

      if (c < '0' || c > '9')
	goto bad;

      if (value > maxv_10)
	goto overflow;

      c -= '0';
      value = 10 * value;

      if (value > maxv - c)
	goto overflow;
      value += c;
    }

  v = (signed int) value;
  if (negative)
    v = -v;

  set_integer (dest, v, length);
  return;

 bad:
  generate_error (ERROR_READ_VALUE, "Bad value during integer read");
  return;

 overflow:
  generate_error (ERROR_READ_OVERFLOW,
		  "Value overflowed during integer read");
  return;
}


/* read_radix()-- This function reads values for non-decimal radixes.
 * The difference here is that we treat the values here as unsigned
 * values for the purposes of overflow.  If minus sign is present and
 * the top bit is set, the value will be incorrect. */

void
read_radix (fnode * f, char *dest, int length, int radix)
{
  unsigned value, maxv, maxv_r;
  int v, w, negative;
  char c, *p;

  w = f->u.w;
  p = read_block (&w);
  if (p == NULL)
    return;

  p = eat_leading_spaces (&w, p);
  if (w == 0)
    {
      set_integer (dest, 0, length);
      return;
    }

  maxv = max_value (length, 0);
  maxv_r = maxv / radix;

  negative = 0;
  value = 0;

  switch (*p)
    {
    case '-':
      negative = 1;
      /* Fall through */

    case '+':
      p++;
      if (--w == 0)
	goto bad;
      /* Fall through */

    default:
      break;
    }

  /* At this point we have a digit-string */
  value = 0;

  for (;;)
    {
      c = next_char (&p, &w);
      if (c == '\0')
	break;

      switch (radix)
	{
	case 2:
	  if (c < '0' || c > '1')
	    goto bad;
	  break;

	case 8:
	  if (c < '0' || c > '7')
	    goto bad;
	  break;

	case 16:
	  switch (c)
	    {
	    case '0':
	    case '1':
	    case '2':
	    case '3':
	    case '4':
	    case '5':
	    case '6':
	    case '7':
	    case '8':
	    case '9':
	      break;

	    case 'a':
	    case 'b':
	    case 'c':
	    case 'd':
	    case 'e':
	    case 'f':
	      c = c - 'a' + '9' + 1;
	      break;

	    case 'A':
	    case 'B':
	    case 'C':
	    case 'D':
	    case 'E':
	    case 'F':
	      c = c - 'A' + '9' + 1;
	      break;

	    default:
	      goto bad;
	    }

	  break;
	}

      if (value > maxv_r)
	goto overflow;

      c -= '0';
      value = radix * value;

      if (maxv - c < value)
	goto overflow;
      value += c;
    }

  v = (signed int) value;
  if (negative)
    v = -v;

  set_integer (dest, v, length);
  return;

 bad:
  generate_error (ERROR_READ_VALUE, "Bad value during integer read");
  return;

 overflow:
  generate_error (ERROR_READ_OVERFLOW,
		  "Value overflowed during integer read");
  return;
}


/* read_f()-- Read a floating point number with F-style editing, which
   is what all of the other floating point descriptors behave as.  The
   tricky part is that optional spaces are allowed after an E or D,
   and the implicit decimal point if a decimal point is not present in
   the input.  */

void
read_f (fnode * f, char *dest, int length)
{
  int w, seen_dp, exponent;
  int exponent_sign, val_sign;
  int ndigits;
  int edigits;
  int i;
  char *p, *buffer;
  char *digits;

  val_sign = 1;
  seen_dp = 0;
  w = f->u.w;
  p = read_block (&w);
  if (p == NULL)
    return;

  p = eat_leading_spaces (&w, p);
  if (w == 0)
    {
      switch (length)
	{
	case 4:
	  *((float *) dest) = 0.0f;
	  break;

	case 8:
	  *((double *) dest) = 0.0;
	  break;

	default:
	  internal_error ("Unsupported real kind during IO");
	}

      return;
    }

  /* Optional sign */

  if (*p == '-' || *p == '+')
    {
      if (*p == '-')
        val_sign = -1;
      p++;

      if (--w == 0)
	goto bad_float;
    }

  exponent_sign = 1;

  /* A digit (or a '.') is required at this point */

  if (!isdigit (*p) && *p != '.')
    goto bad_float;

  /* Remember the position of the first digit.  */
  digits = p;
  ndigits = 0;

  /* Scan through the string to find the exponent.  */
  while (w > 0)
    {
      switch (*p)
	{
	case '.':
	  if (seen_dp)
	    goto bad_float;
	  seen_dp = 1;
	  /* Fall through */

	case '0':
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	case ' ':
	  ndigits++;
	  *p++;
	  w--;
	  break;

	case '-':
	  exponent_sign = -1;
	  /* Fall through */

	case '+':
	  p++;
	  w--;
	  goto exp2;

	case 'd':
	case 'e':
	case 'D':
	case 'E':
	  p++;
	  w--;
	  goto exp1;

	default:
	  goto bad_float;
	}
    }

  /* No exponent has been seen, so we use the current scale factor */
  exponent = -g.scale_factor;
  goto done;

 bad_float:
  generate_error (ERROR_READ_VALUE, "Bad value during floating point read");
  return;

  /* At this point the start of an exponent has been found */
 exp1:
  while (w > 0 && *p == ' ')
    {
      w--;
      p++;
    }

  switch (*p)
    {
    case '-':
      exponent_sign = -1;
      /* Fall through */

    case '+':
      p++;
      w--;
      break;
    }

  if (w == 0)
    goto bad_float;

  /* At this point a digit string is required.  We calculate the value
     of the exponent in order to take account of the scale factor and
     the d parameter before explict conversion takes place. */
 exp2:
  if (!isdigit (*p))
    goto bad_float;

  exponent = *p - '0';
  p++;
  w--;

  while (w > 0 && isdigit (*p))
    {
      exponent = 10 * exponent + *p - '0';
      p++;
      w--;
    }

  /* Only allow trailing blanks */

  while (w > 0)
    {
      if (*p != ' ')
	goto bad_float;
      p++;
      w--;
    }

  exponent = exponent * exponent_sign;

 done:
  /* Use the precision specified in the format if no decimal point has been
     seen.  */
  if (!seen_dp)
    exponent -= f->u.real.d;

  if (exponent > 0)
    {
      edigits = 2;
      i = exponent;
    }
  else
    {
      edigits = 3;
      i = -exponent;
    }

  while (i >= 10)
    {
      i /= 10;
      edigits++;
    }

  i = ndigits + edigits + 1;
  if (val_sign < 0)
    i++;

  if (i < SCRATCH_SIZE) 
    buffer = scratch;
  else
    buffer = get_mem (i);

  /* Reformat the string into a temporary buffer.  As we're using atof it's
     easiest to just leave the dcimal point in place.  */
  p = buffer;
  if (val_sign < 0)
    *(p++) = '-';
  for (; ndigits > 0; ndigits--)
    {
      if (*digits == ' ' && g.blank_status == BLANK_ZERO)
	*p = '0';
      else
	*p = *digits;
      p++;
      digits++;
    }
  *(p++) = 'e';
  sprintf (p, "%d", exponent);

  /* Do the actual conversion.  */
  convert_real (dest, buffer, length);

  if (buffer != scratch)
     free_mem (buffer);

  return;
}


/* read_x()-- Deal with the X/TR descriptor.  We just read some data
 * and never look at it. */

void
read_x (fnode * f)
{
  int n;

  n = f->u.n;
  read_block (&n);
}