strtol.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 149 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
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*    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
*    NON-INFRINGEMENT. Please see the License for the specific language
*    governing rights and limitations under the License.
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*  ========================================================================
*
* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
*               DESCRIBE IT HERE!
*
****************************************************************************/


#include "variety.h"
#include "widechar.h"
#include <stdio.h>
#include <stdlib.h>
#ifdef __WIDECHAR__
    #include <wctype.h>
#else
    #include <ctype.h>
#endif
#include <errno.h>
#include <limits.h>
#include "seterrno.h"

/*
 * this table is the largest value that can safely be multiplied
 * by the associated base without overflowing
 */
static unsigned long nearly_overflowing[] = {
    ULONG_MAX / 2,  ULONG_MAX / 3,  ULONG_MAX / 4,  ULONG_MAX / 5,
    ULONG_MAX / 6,  ULONG_MAX / 7,  ULONG_MAX / 8,  ULONG_MAX / 9,
    ULONG_MAX / 10, ULONG_MAX / 11, ULONG_MAX / 12, ULONG_MAX / 13,
    ULONG_MAX / 14, ULONG_MAX / 15, ULONG_MAX / 16, ULONG_MAX / 17,
    ULONG_MAX / 18, ULONG_MAX / 19, ULONG_MAX / 20, ULONG_MAX / 21,
    ULONG_MAX / 22, ULONG_MAX / 23, ULONG_MAX / 24, ULONG_MAX / 25,
    ULONG_MAX / 26, ULONG_MAX / 27, ULONG_MAX / 28, ULONG_MAX / 29,
    ULONG_MAX / 30, ULONG_MAX / 31, ULONG_MAX / 32, ULONG_MAX / 33,
    ULONG_MAX / 34, ULONG_MAX / 35, ULONG_MAX / 36
};

#define hexstr(p) (p[0] == '0' && (p[1] == 'x' || p[1] == 'X'))


static int radix_value( CHAR_TYPE c )
    {
        if( c >= '0'  &&  c <= '9' ) return( c - '0' );
        c = __F_NAME(tolower,towlower)(c);
        if( c >= 'a'  &&  c <= 'i' ) return( c - 'a' + 10 );
        if( c >= 'j'  &&  c <= 'r' ) return( c - 'j' + 19 );
        if( c >= 's'  &&  c <= 'z' ) return( c - 's' + 28 );
        return( 37 );
    }


static unsigned long int _stol( const CHAR_TYPE *nptr,CHAR_TYPE **endptr,int base,int who)
    {
        const CHAR_TYPE *p;
        const CHAR_TYPE *startp;
        int digit;
        unsigned long int value;
        unsigned long int prev_value;
        CHAR_TYPE sign;
        char overflow;          /*overflow is used as a flag so it does not
                                 *need to be of type CHAR_TYPE */

        if( endptr != NULL ) *endptr = (CHAR_TYPE *)nptr;
        p = nptr;
        while( __F_NAME(isspace,iswspace)(*p) ) ++p;
        sign = *p;
        if( sign == '+'  ||  sign == '-' ) ++p;
        if( base == 0 ) {
            if( hexstr(p) )      base = 16;
            else if( *p == '0' ) base = 8;
            else                 base = 10;
        }
        if( base < 2  ||  base > 36 ) {
            __set_errno( EDOM );
            return( 0 );
        }
        if( base == 16 ) {
            if( hexstr(p) )  p += 2;    /* skip over '0x' */
        }
        startp = p;
        overflow = 0;
        value = 0;
        for(;;) {
            digit = radix_value( *p );
            if( digit >= base ) break;
            if( value > nearly_overflowing[base-2] ) overflow = 1;
            prev_value = value;
            value = value * base + digit;
            if( value < prev_value ) overflow = 1;
            ++p;
        }
        if( p == startp )  p = nptr;
        if( endptr != NULL ) *endptr = (CHAR_TYPE *)p;
        if( who == 1 ) {
            if( value >= 0x80000000 ) {
                if( value == 0x80000000  &&  sign == '-' ) {
                    ;  /* OK */
                } else {
                    overflow = 1;
                }
            }
        }
        if( overflow ) {
            __set_errno( ERANGE );
            if( who == 0 )     return( ULONG_MAX );
            if( sign == '-' )  return( LONG_MIN );
            return( LONG_MAX );
        }
        if( sign == '-' )  value = - value;
        return( value );
    }


_WCRTLINK unsigned long int __F_NAME(strtoul,wcstoul)( const CHAR_TYPE *nptr,
                CHAR_TYPE **endptr, int base )
    {
        return( _stol( nptr, endptr, base, 0 ) );
    }


_WCRTLINK long int __F_NAME(strtol,wcstol)( const CHAR_TYPE *nptr, CHAR_TYPE **endptr, int base )
    {
        return( _stol( nptr, endptr, base, 1 ) );
    }