#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include "perf_counter.h"

#ifdef __x86_64__
# define __NR_perf_counter_open	295
#endif

#ifdef __i386__
# define __NR_perf_counter_open 333
#endif

#ifdef __powerpc__
# define __NR_perf_counter_open 319
#endif

#define PR_TASK_PERF_COUNTERS_DISABLE           31
#define PR_TASK_PERF_COUNTERS_ENABLE            32

int sys_perf_counter_open(struct perf_counter_hw_event *hw_event,
			  pid_t pid, int cpu, int group_fd, unsigned long flags)
{
	return syscall(__NR_perf_counter_open, hw_event, pid, cpu, group_fd,
		       flags);
}

#define MAX_CTRS	50
#define LOOPS	1000000000

void do_work(void)
{
	int i;

	for (i = 0; i < LOOPS; ++i)
		asm volatile("" : : "g" (i));
}

main(int ac, char **av)
{
	int tsk0;
	int hwfd[MAX_CTRS], tskfd[MAX_CTRS];
	struct perf_counter_hw_event tsk_event;
	struct perf_counter_hw_event hw_event;
	unsigned long long vt0, vt[MAX_CTRS], vh[MAX_CTRS], vtsum, vhsum;
	int i, n, nhw;
	int verbose = 0;
	double ratio;

	nhw = 8;
	while ((i = getopt(ac, av, "c:v")) != -1) {
		switch (i) {
		case 'c':
			n = atoi(optarg);
			break;
		case 'v':
			verbose = 1;
			break;
		case '?':
			fprintf(stderr, "Usage: %s [-c #hwctrs] [-v]\n", av[0]);
			exit(1);
		}
	}

	if (nhw < 0 || nhw > MAX_CTRS - 4) {
		fprintf(stderr, "invalid number of hw counters specified: %d\n",
			nhw);
		exit(1);
	}

	n = nhw + 4;

	memset(&tsk_event, 0, sizeof(tsk_event));
	tsk_event.type = PERF_COUNT_TASK_CLOCK;
	tsk_event.disabled = 1;

	memset(&hw_event, 0, sizeof(hw_event));
	hw_event.disabled = 1;
	hw_event.type = PERF_COUNT_INSTRUCTIONS;

	tsk0 = sys_perf_counter_open(&tsk_event, 0, -1, -1, 0);
	if (tsk0 == -1) {
		perror("perf_counter_open");
		exit(1);
	}

	tsk_event.disabled = 0;
	for (i = 0; i < n; ++i) {
		hwfd[i] =  sys_perf_counter_open(&hw_event, 0, -1, -1, 0);
		tskfd[i] = sys_perf_counter_open(&tsk_event, 0, -1, hwfd[i], 0);
		if (tskfd[i] == -1 || hwfd[i] == -1) {
			perror("perf_counter_open");
			exit(1);
		}
	}

	prctl(PR_TASK_PERF_COUNTERS_ENABLE);
	do_work();
	prctl(PR_TASK_PERF_COUNTERS_DISABLE);

	if (read(tsk0, &vt0, sizeof(vt0)) != sizeof(vt0)) {
		fprintf(stderr, "error reading task clock counter\n");
		exit(1);
	}

	vtsum = vhsum = 0;
	for (i = 0; i < n; ++i) {
		if (read(tskfd[i], &vt[i], sizeof(vt[i])) != sizeof(vt[i]) ||
		    read(hwfd[i], &vh[i], sizeof(vh[i])) != sizeof(vh[i])) {
			fprintf(stderr, "error reading counter(s)\n");
			exit(1);
		}
		vtsum += vt[i];
		vhsum += vh[i];
	}

	printf("overall task clock: %lld\n", vt0);
	printf("hw sum: %lld, task clock sum: %lld\n", vhsum, vtsum);
	if (verbose) {
		printf("hw counters:");
		for (i = 0; i < n; ++i)
			printf(" %lld", vh[i]);
		printf("\ntask clock counters:");
		for (i = 0; i < n; ++i)
			printf(" %lld", vt[i]);
		printf("\n");
	}
	ratio = (double)vtsum / vt0;
	printf("ratio: %.2f\n", ratio);
	if (ratio > nhw + 0.0001) {
		fprintf(stderr, "test failed\n");
		exit(1);
	}

	fprintf(stderr, "test passed\n");
	exit(0);
}