glibc strverscmp
int
__strverscmp (const char *s1, const char *s2)
{
const unsigned char *p1 = (const unsigned char *) s1;
const unsigned char *p2 = (const unsigned char *) s2;
/* Symbol(s) 0 [1-9] others
Transition (10) 0 (01) d (00) x */
static const uint8_t next_state[] =
{
/* state x d 0 */
/* S_N */ S_N, S_I, S_Z,
/* S_I */ S_N, S_I, S_I,
/* S_F */ S_N, S_F, S_F,
/* S_Z */ S_N, S_F, S_Z
};
static const int8_t result_type[] =
{
/* state x/x x/d x/0 d/x d/d d/0 0/x 0/d 0/0 */
/* S_N */ CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
/* S_I */ CMP, -1, -1, +1, LEN, LEN, +1, LEN, LEN,
/* S_F */ CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
/* S_Z */ CMP, +1, +1, -1, CMP, CMP, -1, CMP, CMP
};
if (p1 == p2)
return 0;
unsigned char c1 = *p1++;
unsigned char c2 = *p2++;
/* Hint: '0' is a digit too. */
int state = S_N + ((c1 == '0') + (__my_isdigit (c1) != 0));
int diff;
while ((diff = c1 - c2) == 0)
{
if (c1 == '\0')
return diff;
state = next_state[state];
c1 = *p1++;
c2 = *p2++;
state += (c1 == '0') + (__my_isdigit (c1) != 0);
}
state = result_type[state * 3 + (((c2 == '0') + (__my_isdigit (c2) != 0)))];
switch (state)
{
case CMP:
return diff;
case LEN:
while (__my_isdigit (*p1++))
if (!__my_isdigit (*p2++))
return 1;
return __my_isdigit (*p2) ? -1 : diff;
default:
return state;
}
}