#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>
#include <string.h>
#include <pthread.h>
#include <errno.h>
#include <sys/mman.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


#define NTHR 1

struct thr_arg {
	unsigned long delay;
};

struct thr_arg thr_arg[NTHR] = { { .delay = 1000000 } };
pthread_t thr[NTHR];

#define DIFFNSEC(end, start) ((end.tv_sec - start.tv_sec) * 1000000000UL + \
		(end.tv_nsec - start.tv_nsec))
#define TIMER_KIND CLOCK_MONOTONIC_RAW /* CLOCK_THREAD_CPUTIME_ID */

static int print_cpu_last_executed_on(void)
{
	int ret = 0;
	char fn[256];
	char *result;
	pid_t tid = syscall(SYS_gettid);
	int fd;
	int offset;
	int amount = 0;
	char *list;
	char *token;
	int i;
	int cpu;

	sprintf(fn, "/proc/%d/task/%d/stat", getpid(), (int)tid);
	fd = open(fn, O_RDONLY);
	if (fd == -1) {
		printf("open() failed\n");
		goto fn_fail;
	}

	result = malloc(65536);
	if (result == NULL) {
		printf("malloc() failed");
		goto fn_fail;
	}

	offset = 0;
	while (1) {
		amount = read(fd, result + offset, 65536);
		//		printf("amount=%d\n", amount);
		if (amount == -1) {
			printf("read() failed");
			goto fn_fail;
		}
		if (amount == 0) {
			goto eof;
		}
		offset += amount;
	}
 eof:;
	//printf("result:%s\n", result);

	list = result;
	for (i = 0; i < 39; i++) {
		token = strsep(&list, " ");
	}

	cpu = sched_getcpu();
	if (cpu == -1) {
		printf("getcpu() failed\n");
		goto fn_fail;
	}

	printf("[INFO] stat-cpu=%02d,sched_getcpu=%02d,tid=%d\n",
		token ? atoi(token) : -1, cpu, tid);
 fn_exit:
	free(result);
	return ret;
 fn_fail:
	ret = -1;
	goto fn_exit;
}

static inline void asm_loop(unsigned long n)
{
	int j;

	for (j = 0; j < (n); j++) {
		asm volatile(
			     "movq $0, %%rcx\n\t"
			     "1:\t"
			     "addq $1, %%rcx\n\t"
			     "cmpq $99, %%rcx\n\t"
			     "jle 1b\n\t"
			     :
			     :
			     : "rcx", "cc");
	}
}

void *util_thread(void *_arg)
{
	struct thr_arg *arg = (struct thr_arg *)_arg;

	print_cpu_last_executed_on();
	asm_loop(arg->delay);
	pthread_exit(NULL);
}

int main(int argc, char **argv)
{
	int i;
	int ret = 0;

	for (i = 0; i < NTHR; i++) {

		if ((ret = pthread_create(&thr[i], NULL,
			util_thread, &thr_arg[i]))) {
			fprintf(stderr, "ERROR: pthread_create failed (%d)\n",
				ret);
			ret = -EINVAL;
			goto out;
		}
	}

	for (i = 0; i < NTHR; i++) {
		pthread_join(thr[i], NULL);
	}

 out:
	return ret;
}