add directory gnu

gnu/glibc/glibc-1.03/stdlib/strtod.c

@@ -0,0 +1,179 @@
+/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <localeinfo.h>
+#include <errno.h>
+#include <float.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+
+/* Convert NPTR to a double.  If ENDPTR is not NULL, a pointer to the
+   character after the last one used in the number is put in *ENDPTR.  */
+double
+DEFUN(strtod, (nptr, endptr), CONST char *nptr AND char **endptr)
+{
+  register CONST char *s;
+  short int sign;
+  wchar_t decimal;	/* Decimal point character.  */
+
+  /* The number so far.  */
+  double num;
+
+  int got_dot;		/* Found a decimal point.  */
+  int got_digit;	/* Seen any digits.  */
+
+  /* The exponent of the number.  */
+  long int exponent;
+
+  if (nptr == NULL)
+    {
+      errno = EINVAL;
+      goto noconv;
+    }
+
+  /* Figure out the decimal point character.  */
+  if (mbtowc(&decimal, _numeric_info->decimal_point, 1) <= 0)
+    decimal = (wchar_t) *_numeric_info->decimal_point;
+
+  s = nptr;
+
+  /* Eat whitespace.  */
+  while (isspace(*s))
+    ++s;
+
+  /* Get the sign.  */
+  sign = *s == '-' ? -1 : 1;
+  if (*s == '-' || *s == '+')
+    ++s;
+
+  num = 0.0;
+  got_dot = 0;
+  got_digit = 0;
+  exponent = 0;
+  for (;; ++s)
+    {
+      if (isdigit (*s))
+	{
+	  got_digit = 1;
+
+	  /* Make sure that multiplication by 10 will not overflow.  */
+	  if (num > DBL_MAX * 0.1)
+	    /* The value of the digit doesn't matter, since we have already
+	       gotten as many digits as can be represented in a `double'.
+	       This doesn't necessarily mean the result will overflow.
+	       The exponent may reduce it to within range.
+
+	       We just need to record that there was another
+	       digit so that we can multiply by 10 later.  */
+	    ++exponent;
+	  else
+	    num = (num * 10.0) + (*s - '0');
+
+	  /* Keep track of the number of digits after the decimal point.
+	     If we just divided by 10 here, we would lose precision.  */
+	  if (got_dot)
+	    --exponent;
+	}
+      else if (!got_dot && (wchar_t) *s == decimal)
+	/* Record that we have found the decimal point.  */
+	got_dot = 1;
+      else
+	/* Any other character terminates the number.  */
+	break;
+    }
+
+  if (!got_digit)
+    goto noconv;
+
+  if (tolower(*s) == 'e')
+    {
+      /* Get the exponent specified after the `e' or `E'.  */
+      int save = errno;
+      char *end;
+      long int exp;
+
+      errno = 0;
+      ++s;
+      exp = strtol(s, &end, 10);
+      if (errno == ERANGE)
+	{
+	  /* The exponent overflowed a `long int'.  It is probably a safe
+	     assumption that an exponent that cannot be represented by
+	     a `long int' exceeds the limits of a `double'.  */
+	  if (endptr != NULL)
+	    *endptr = end;
+	  if (exp < 0)
+	    goto underflow;
+	  else
+	    goto overflow;
+	}
+      else if (end == s)
+	/* There was no exponent.  Reset END to point to
+	   the 'e' or 'E', so *ENDPTR will be set there.  */
+	end = (char *) s - 1;
+      errno = save;
+      s = end;
+      exponent += exp;
+    }
+
+  if (endptr != NULL)
+    *endptr = (char *) s;
+
+  if (num == 0.0)
+    return 0.0;
+
+  /* Multiply NUM by 10 to the EXPONENT power,
+     checking for overflow and underflow.  */
+
+  if (exponent < 0)
+    {
+      if (num < DBL_MIN * pow(10.0, (double) -exponent))
+	goto underflow;
+    }
+  else if (exponent > 0)
+    {
+      if (num > DBL_MAX * pow(10.0, (double) -exponent))
+	goto overflow;
+    }
+
+  num *= pow(10.0, (double) exponent);
+
+  return num * sign;
+
+ overflow:
+  /* Return an overflow error.  */
+  errno = ERANGE;
+  return HUGE_VAL * sign;
+
+ underflow:
+  /* Return an underflow error.  */
+  if (endptr != NULL)
+    *endptr = (char *) nptr;
+  errno = ERANGE;
+  return 0.0;
+
+ noconv:
+  /* There was no number.  */
+  if (endptr != NULL)
+    *endptr = (char *) nptr;
+  return 0.0;
+}