ref: c75d39d84fcaf779903f1e76c1ffebccac2de3cc
dir: /src/libc/stdlib/atol.c/
#include <ctype.h>
#include <stdlib.h>
#undef atol
long
atol(const char *s)
{
int d, sign = -1;
long n;
while (isspace(*s))
++s;
switch (*s) {
case '-':
sign = 1;
case '+':
++s;
}
/* Compute n as a negative number to avoid overflow on LONG_MIN */
for (n = 0; (d = _dtoi(*s)) < 10; ++s)
n = n*10 - d;
return sign * n;
}