amiga-clib2/library/stdlib_strtod.c

/*
 * $Id: stdlib_strtod.c,v 1.1.1.1 2004-07-26 16:32:10 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2004 by Olaf Barthel <olsen@sourcery.han.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _STDLIB_NULL_POINTER_CHECK_H
#include "stdlib_null_pointer_check.h"
#endif /* _STDLIB_NULL_POINTER_CHECK_H */

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

#ifndef _STDLIB_HEADERS_H
#include "stdlib_headers.h"
#endif /* _STDLIB_HEADERS_H */

#ifndef _LOCALE_HEADERS_H
#include "locale_headers.h"
#endif /* _LOCALE_HEADERS_H */

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

#ifndef _MATH_FP_SUPPORT_H
#include "math_fp_support.h"
#endif /* _MATH_FP_SUPPORT_H */

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

#if defined(FLOATING_POINT_SUPPORT)

double
strtod(const char *str, char ** ptr)
{
	double sum = 0.0;
	double new_sum;
	double result;
	int decimal_point_matches;
	int is_negative;
	int error = 0;
	char c;

	ENTER();

	SHOWSTRING(str);
	SHOWPOINTER(ptr);

	assert( str != NULL );

	#if defined(CHECK_FOR_NULL_POINTERS)
	{
		if(str == NULL)
		{
			SHOWMSG("invalid str parameter");

			result = HUGE_VAL;
			errno = EFAULT;
			goto out;
		}
	}
	#endif /* CHECK_FOR_NULL_POINTERS */

	/* Skip all leading blanks. */
	while((c = (*str)) != '\0')
	{
		if(NOT isspace(c))
			break;

		str++;
	}

	/* The first character may be a sign. */
	if((*str) == '-')
	{
		/* It's a negative number. */
		is_negative = 1;

		str++;
	}
	else
	{
		/* It's not going to be negative. */
		is_negative = 0;

		/* But there may be a sign we will choose to
		 * ignore.
		 */
		if((*str) == '+')
			str++;
	}

	/* We begin by trying to convert all the digits
	 * preceding the decimal point.
	 */
	while((c = (*str)) != '\0')
	{
		if('0' <= c && c <= '9')
		{
			str++;

			if(error == 0)
			{
				new_sum = (10 * sum) + (c - '0');
				if(new_sum < sum) /* overflow? */
					error = ERANGE;
				else
					sum = new_sum;
			}
		}
		else
		{
			break;
		}
	}

	/* Did we find the decimal point? We accept both the
	 * locale configured decimal point and the plain old
	 * dot.
	 */
	decimal_point_matches = 0;
	if(__locale_table[LC_NUMERIC] != NULL)
	{
		char * point;

		point = (char *)__locale_table[LC_NUMERIC]->loc_DecimalPoint;
		if((*point) == (*str))
		{
			decimal_point_matches = 1;

			/* Skip the decimal point. */
			str++;
		}
	}

	if(NOT decimal_point_matches)
	{
		if((*str) == '.')
		{
			decimal_point_matches = 1;

			/* Skip the decimal point. */
			str++;
		}
	}

	if(decimal_point_matches)
	{
		double divisor = 0.1;

		/* Process all digits following the decimal point. */
		while((c = (*str)) != '\0')
		{
			if('0' <= c && c <= '9')
			{
				str++;

				if(error == 0 && divisor != 0.0)
				{
					new_sum = sum + (c - '0') * divisor;
					if(new_sum < sum) /* overflow? */
						error = ERANGE;
					else
						sum = new_sum;

					divisor = divisor / 10.0;
				}
			}
			else
			{
				break;
			}
		}
	}

	/* If there is a scale indicator attached, process it. */
	if((*str) == 'e' || (*str) == 'E')
	{
		int exponent_is_negative;
		int new_exponent;
		int exponent = 0;

		/* Skip the indicator. */
		str++;

		/* Take care of the exponent's sign. */
		if((*str) == '-')
		{
			exponent_is_negative = 1;
			str++;
		}
		else
		{
			exponent_is_negative = 0;

			if((*str) == '+')
				str++;
		}

		/* Again, process all digits to follow. */
		while((c = (*str)) != '\0')
		{
			if('0' <= c && c <= '9')
			{
				str++;

				if(error == 0)
				{
					new_exponent = (10 * exponent) + (c - '0');
					if(new_exponent < exponent) /* overflow? */
						error = ERANGE;
					else
						exponent = new_exponent;
				}
			}
			else
			{
				break;
			}
		}

		/* If the exponent is valid, scale the number
		 * accordingly.
		 */
		if(exponent != 0)
		{
			if(exponent_is_negative)
			{
				double divisor;

				/* A negative exponent means division. */
				divisor = pow(10.0,(double)exponent);
				if(divisor != 0.0)
				{
					new_sum = sum / divisor;
					if(new_sum == 0.0 && sum != 0.0)
						error = ERANGE;
					else
						sum = new_sum;
				}
				else
				{
					error = ERANGE;
				}
			}
			else
			{
				/* A positive exponent means multiplication. */
				new_sum = sum * pow(10.0,(double)exponent);
				if(new_sum < sum)
					error = ERANGE;
				else
					sum = new_sum;
			}
		}
	}

	if(error != 0)
	{
		errno = error;

		sum = HUGE_VAL;
	}

	if(is_negative)
		sum = (-sum);

	result = sum;

	/* If desired, remember where we stopped reading the
	 * number from the buffer.
	 */
	if(ptr != NULL)
		(*ptr) = (char *)str;

 out:

	RETURN(result);
	return(result);
}

#endif /* FLOATING_POINT_SUPPORT */