#include <stdio.h>
#include <time.h>

typedef _Bool bool;
#define true 1
#define false 0
#define unlikely(x)	(x)
typedef unsigned int u32;
typedef unsigned long long u64;
#define HASH_LEN_DECLARE u32 hash; u32 len

struct qstr {
        union {
                struct {
                        HASH_LEN_DECLARE;
                };
                u64 hash_len;
        };
        const char *name;
};

bool is_dot_dotdot_1(const struct qstr *str)
{
	if (str->len == 1 && str->name[0] == '.')
		return true;
	if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
		return true;
	return false;
}

bool is_dot_dotdot_2(const struct qstr *str)
{
	if (unlikely(str->name[0] == '.')) {
		if (str->len < 2 || (str->len == 2 && str->name[1] == '.'))
			return false;
	}

	return true;
}

double time_sub(struct timespec *before, struct timespec *after)
{
	struct timespec diff = { .tv_sec  = after->tv_sec  - before->tv_sec,
				 .tv_nsec = after->tv_nsec - before->tv_nsec };
	if (diff.tv_nsec < 0) {
		diff.tv_nsec += 1000 * 1000 * 1000;
		diff.tv_sec -= 1;
	}

	return diff.tv_sec + diff.tv_nsec * 0.0000000001d;
}

bool res;

void mytime(const struct qstr *qstr)
{
	unsigned int i;
	struct timespec start, middle, end;

	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &start);
	for (i = 0; i < 100000000; i++)
		res = is_dot_dotdot_1(qstr);
	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &middle);
	for (i = 0; i < 100000000; i++)
		res = is_dot_dotdot_2(qstr);
	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &end);

	printf("qstr %s time_1 %f time_2 %f\n", qstr->name,
			time_sub(&start, &middle), time_sub(&middle, &end));
}

int main(int argc, char **argv)
{
	struct qstr dot = { .len = 1, .name = "." };
	struct qstr dotdot = { .len = 2, .name = ".." };
	struct qstr a = { .len = 1, .name = "a" };
	struct qstr matthew = { .len = 7, .name = "matthew" };
	struct qstr dota = { .len = 2, .name = ".a" };
	struct qstr comma = { .len = 1, .name = "," };

	mytime(&dot);
	mytime(&dotdot);
	mytime(&a);
	mytime(&matthew);
	mytime(&dota);
	mytime(&comma);

	return 0;
}