strtoi.c

来自「freedos32的源代码」· C语言 代码 · 共 61 行

/* Project:     OSLib
 * Description: The OS Construction Kit
 * Date:                1.6.2000
 * Idea by:             Luca Abeni & Gerardo Lamastra
 *
 * OSLib is an SO project aimed at developing a common, easy-to-use
 * low-level infrastructure for developing OS kernels and Embedded
 * Applications; it partially derives from the HARTIK project but it
 * currently is independently developed.
 *
 * OSLib is distributed under GPL License, and some of its code has
 * been derived from the Linux kernel source; also some important
 * ideas come from studying the DJGPP go32 extender.
 *
 * We acknowledge the Linux Community, Free Software Foundation,
 * D.J. Delorie and all the other developers who believe in the
 * freedom of software and ideas.
 *
 * For legalese, check out the included GPL license.
 */

#include <ll/i386/stdlib.h>
#include <ll/i386/string.h>
#include <ll/i386/limits.h>
#include <ll/stdarg.h>
#include <ll/ctype.h>
#include <ll/math.h>

FILE(strtoi);

long int strtoi(char *s,int base,char **scan_end)
{
    int sign,value,overflow = 0;
    long int result = 0,oldresult;
    /* Evaluate sign */
    if (*s == '-') {
	sign = -1;
	s++;
    } else if (*s == '+') {
	sign = 1;
	s++;
    }
    else sign = 1;
    /* Skip trailing zeros */
    while (*s == '0') s++;
    /* Convert number */
    while (isnumber(*s,base)) {
	value = tonumber(*s++);
	if (value > base || value < 0) return(0);
	oldresult = result;
	result *= base;
	result += value;
	/* Detect overflow */
	if (oldresult > result) overflow = 1;
    }
    if (scan_end != 0L) *scan_end = s;
    if (overflow) result = INT_MAX;
    result *= sign;
    return(result);
}