#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <ctype.h>
#include <string.h>
#include <sys/io.h>

static void restore(void);

static void __attribute__ ((format (printf, 1, 2)))
fatal(const char *msg, ...)
{
	va_list ap;

	fprintf(stderr, "fatal error: ");

	va_start(ap, msg);
	vfprintf (stderr, msg, ap);
	va_end(ap);
	restore();
	exit(1);
}

static int port_start = -1;
static int verbose = 1;

#define PORT(name,len,val) \
static unsigned in_##name() { \
	unsigned res = in##len(port_start+(val)); \
	if (verbose) printf("*%s -> %x\n", #name, res); \
	return res; \
} \
static void out_##name(unsigned v) { \
	if (verbose) printf("%x -> *%s\n", v, #name); \
	out##len(v,port_start+(val)); \
}

PORT(Timer,l,0x48)
PORT(IntrMask,w,0x3c)
PORT(IntrStatus,w,0x3E)
PORT(TimerInt,l,0x54)

static void my_sleep(int n)
{
	if (verbose) {
		printf("sleeping %d seconds...", n);
		fflush(stdout);
	}
	sleep(n); 
	if (verbose) printf("\n\n");
}
#define sleep(n) my_sleep(n)

static int saved_mask = -1;
static int saved_tmr = -1;

static void restore(void)
{
	if (saved_mask >= 0)
		out_IntrMask(saved_mask);
	if (saved_tmr >= 0)
		out_TimerInt(saved_tmr);
	out_Timer(0);
}

static void stop(int sig)
{
	restore();
	printf("bye bye\n");
	exit(1);
}

#define CLK 33000000

int main()
{
	// find port address from lspci command
	FILE *f = popen("lspci -vn", "r");
	if (!f)
		fatal("executing lspci...\n");
	char line[128];
	int in_card = 0;
	while(fgets(line, sizeof(line), f)) {
		// parse header, select our card
		if (!isspace(line[0])) {
			in_card = 0;
			if (strstr(line, " 10ec:8139 ") != NULL)
				in_card = 1;
			continue;
		}

		// skip other cards
		if (!in_card) continue;

		if (sscanf(line, " I/O ports at %x [size", &port_start) == 1)
			break;
	}
	pclose(f);
	if (port_start < 0)
		fatal("port not found!\n");
	printf("found card at address %x\n", port_start);



	// enable direct port access
	if (iopl(3))
		fatal("iopl...\n");

	signal(SIGTERM, stop);
	signal(SIGINT, stop);

	saved_mask = in_IntrMask();
	saved_tmr  = in_TimerInt();

	const unsigned from = 0.95 * CLK;
	const unsigned to = 1.6 * CLK;

	out_IntrMask(0);

	in_IntrStatus();
	in_Timer();
	in_Timer();

	// Test 1. test counter continue and continue
	out_TimerInt(0); // disable timer
	out_IntrStatus(0x4000);
	out_Timer(12345); // reset timer to 0
	unsigned curr = in_Timer();
	unsigned cnt;
	if (curr > 0.1 * CLK)
		fatal("time too big %u\n", curr);
	for (cnt=0;;) {
		sleep(1);
		unsigned prev = curr;
		curr = in_Timer();

		// test skep is in a specific range
		unsigned diff = (curr-prev) & 0xffffffffu;
		if (diff < from || diff > to)
			fatal("Invalid diff %u (%u-%u)\n", diff, from,to);
		if (curr < prev && ++cnt == 3)
			break;
	}

	// Test 2. Check we didn't get an interrupt with TimerInt == 0
	if (in_IntrStatus() & 0x4000)
		fatal("got an interrupt\n");

	// Test 3. Setting TimerInt to 1 and Timer to 0 get interrupt
	out_TimerInt(1);
	out_Timer(0);
	if ((in_IntrStatus() & 0x4000) == 0)
		fatal("we should have an interrupt here!\n");

	// Test 3. Check acknowledge
	out_IntrStatus(0x4000);
	if (in_IntrStatus() & 0x4000)
		fatal("got an interrupt\n");

	// Test. Status set after Timer reset
	out_Timer(0);
	out_TimerInt(0);
	out_IntrStatus(0x4000);
	curr = in_Timer();
	out_TimerInt(curr + 0.5 * CLK);
	sleep(1);
	out_Timer(0);
	if ((in_IntrStatus() & 0x4000) == 0)
		fatal("we should have an interrupt here!\n");

	// Test. Status set after TimerInt reset
	out_Timer(0);
	out_TimerInt(0);
	out_IntrStatus(0x4000);
	curr = in_Timer();
	out_TimerInt(curr + 0.5 * CLK);
	sleep(1);
	out_TimerInt(0);
	if ((in_IntrStatus() & 0x4000) == 0)
		fatal("we should have an interrupt here!\n");

	// Test 4. Increment TimerInt we should see an interrupt
	curr = in_Timer();
	unsigned next = curr + 5.0 * CLK;
	out_TimerInt(next);
	for (cnt=0;;) {
		sleep(1);
		unsigned prev = curr;
		curr = in_Timer();
		unsigned diff = (curr-prev) & 0xffffffffu;
		if (diff < from || diff > to)
			fatal("Invalid diff %u (%u-%u)\n", diff, from,to);
		if (cnt < 3 && curr > next) {
			if ((in_IntrStatus() & 0x4000) == 0)
				fatal("we should have an interrupt here!\n");
			out_IntrStatus(0x4000);
			next = curr + 5.0 * CLK;
			out_TimerInt(next);
			if (++cnt == 3)
				out_TimerInt(1);
		// Test 5. Second time we pass from 0 should see an interrupt
		} else if (cnt >= 3 && curr < prev) {
		 	// here we should have an interrupt
			if ((in_IntrStatus() & 0x4000) == 0)
				fatal("we should have an interrupt here!\n");
			out_IntrStatus(0x4000);
			if (++cnt == 5) break;
		}
	}

	printf("Everythink is ok!\n");
	verbose = 0;
	restore();
	return 0;

	/* irq is set when Timer == TimerInt 
 	 * TimerInt == 0 disable timer
	 * Timer keep counting always
	 * If you set ANY value to Timer Timer is set to 0
 	 */
}

/*
test
- 0 TimerInt non setta mai irq
- settanto a 1 TimerInt e poi resettando Timer subito irq
- passando seconda volta setta comunque
- scrivo qualsiasi in Timer valore e va a 0 comunque
*/