V10/libc/gen/actol.c

long
atol(s)
register char *s;
{
	register long n;
	int f;

	n = 0;
	f = 0;
	while((*s == ' ') || (*s == '\t'))
		s++;
	if(*s == '-') {
		f = 1;
		s++;
	}
	if(s[0]=='0' && s[1]){
		if(s[1]=='x' || s[1]=='X'){
			s += 2;
			for(;;){
				if(*s >= '0' && *s <= '9')
					n = n*16 + *s++ - '0';
				else if(*s >= 'a' && *s <= 'f')
					n = n*16 + *s++ - 'a' + 10;
				else if(*s >= 'A' && *s <= 'F')
					n = n*16 + *s++ - 'A' + 10;
				else
					break;
			}
		} else
			while(*s >= '0' && *s <= '7')
				n = n*8 + *s++ - '0';
	} else
		while(*s >= '0' && *s <= '9')
			n = n*10 + *s++ - '0';
	if(f)
		n = -n;
	return n;
}