cpython/Python/mystrtoul.c

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI or Corporation for National Research Initiatives or
CNRI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

While CWI is the initial source for this software, a modified version
is made available by the Corporation for National Research Initiatives
(CNRI) at the Internet address ftp://ftp.python.org.

STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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******************************************************************/

#include "config.h"

/* Convert a possibly signed character to a nonnegative int */
/* XXX This assumes characters are 8 bits wide */
#ifdef __CHAR_UNSIGNED__
#define Py_CHARMASK(c)		(c)
#else
#define Py_CHARMASK(c)		((c) & 0xff)
#endif

/* strtol and strtoul, renamed to avoid conflicts */

/*
**	strtoul
**		This is a general purpose routine for converting
**		an ascii string to an integer in an arbitrary base.
**		Leading white space is ignored.  If 'base' is zero
**		it looks for a leading 0, 0x or 0X to tell which
**		base.  If these are absent it defaults to 10.
**		Base must be 0 or between 2 and 36 (inclusive).
**		If 'ptr' is non-NULL it will contain a pointer to
**		the end of the scan.
**		Errors due to bad pointers will probably result in
**		exceptions - we don't check for them.
*/

#include <ctype.h>
#include <errno.h>

unsigned long
PyOS_strtoul(str, ptr, base)
register char *	str;
char **		ptr;
int		base;
{
    register unsigned long	result;	/* return value of the function */
    register int		c;	/* current input character */
    register unsigned long	temp;	/* used in overflow testing */
    int				ovf;	/* true if overflow occurred */

    result = 0;
    ovf = 0;

/* catch silly bases */
    if (base != 0 && (base < 2 || base > 36))
    {
	if (ptr)
	    *ptr = str;
	return 0;
    }

/* skip leading white space */
    while (*str && isspace(Py_CHARMASK(*str)))
	str++;

/* check for leading 0 or 0x for auto-base or base 16 */
    switch (base)
    {
    case 0:		/* look for leading 0, 0x or 0X */
	if (*str == '0')
	{
	    str++;
	    if (*str == 'x' || *str == 'X')
	    {
		str++;
		base = 16;
	    }
	    else
		base = 8;
	}
	else
	    base = 10;
	break;

    case 16:	/* skip leading 0x or 0X */
	if (*str == '0' && (*(str+1) == 'x' || *(str+1) == 'X'))
	    str += 2;
	break;
    }

/* do the conversion */
    while ((c = Py_CHARMASK(*str)) != '\0')
    {
	if (isdigit(c) && c - '0' < base)
	    c -= '0';
	else
	{
	    if (isupper(c))
		c = tolower(c);
	    if (c >= 'a' && c <= 'z')
		c -= 'a' - 10;
	    else	/* non-"digit" character */
		break;
	    if (c >= base)	/* non-"digit" character */
		break;
	}
	temp = result;
	result = result * base + c;
#ifndef MPW
	if ((result - c) / base != temp)	/* overflow */
	    ovf = 1;
#endif
	str++;
    }

/* set pointer to point to the last character scanned */
    if (ptr)
	*ptr = str;
    if (ovf)
    {
	result = (unsigned long) ~0L;
	errno = ERANGE;
    }
    return result;
}

long
PyOS_strtol(str, ptr, base)
char *	str;
char ** ptr;
int	base;
{
	long result;
	char sign;
	
	while (*str && isspace(Py_CHARMASK(*str)))
		str++;
	
	sign = *str;
	if (sign == '+' || sign == '-')
		str++;
	
	result = (long) PyOS_strtoul(str, ptr, base);
	
	/* Signal overflow if the result appears negative,
	   except for the largest negative integer */
	if (result < 0 && !(sign == '-' && result == -result)) {
		errno = ERANGE;
		result = 0x7fffffff;
	}
	
	if (sign == '-')
		result = -result;
	
	return result;
}