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/*
* Copyright © 2018 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <X11/Xlib.h>
#include <X11/extensions/Xpresent.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <time.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
struct monitor {
int fd;
};
#define BILLION 1000000000ULL
#define MILLION 1000000ULL
static uint64_t vid_clock(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return ((uint64_t) ts.tv_sec * BILLION + (uint64_t) ts.tv_nsec);
}
static void flush(int fd)
{
char buf[1024];
int n;
int avail;
for (;;) {
n = ioctl(fd, FIONREAD, &avail);
if (n < 0 || avail <= 0)
break;
read(fd, buf, avail);
}
}
static uint64_t vid_time[2];
static int vid_value;
static pthread_mutex_t time_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t time_cond = PTHREAD_COND_INITIALIZER;
static void *monitor_device(void *arg)
{
struct monitor *m = arg;
int fd = m->fd;
char buf[256];
int n;
struct termios termios;
uint64_t t;
int v;
tcgetattr(fd, &termios);
cfmakeraw(&termios);
cfsetospeed(&termios, B9600);
cfsetispeed(&termios, B9600);
tcsetattr(fd, TCSAFLUSH, &termios);
flush(fd);
write(fd, "E 0\nV 0\n", 8);
sleep(1);
flush(fd);
write(fd, "V 1\n", 4);
for (;;) {
n = read(fd, buf, sizeof(buf));
if (n < 0) {
perror("read");
return NULL;
}
t = vid_clock();
switch(buf[0]) {
case '1':
case '0':
v = buf[0] - '0';
pthread_mutex_lock(&time_mutex);
vid_value = v;
vid_time[v] = t;
pthread_mutex_unlock(&time_mutex);
pthread_cond_signal(&time_cond);
break;
}
}
}
#define W 512
#define H 512
#define DEV "/dev/ttyACM0"
int main(int argc, char **argv)
{
Display *dpy;
int scr;
Window root;
Window win;
GC gc;
Pixmap pix;
int v = 0;
struct timespec ts = { .tv_sec = 0, .tv_nsec = 100 * MILLION };
pthread_t monitor_thread;
struct monitor monitor;
uint64_t put, show, got;
uint32_t serial = 0;
XEvent ev;
int ge_event_base, ge_error_base;
int present_opcode, present_event_base, present_error_base;
bool got_event, exposed;
XSetWindowAttributes swa = {
.event_mask = ExposureMask
};
monitor.fd = open(DEV, O_RDWR);
if (monitor.fd < 0) {
perror(DEV);
exit(1);
}
pthread_create(&monitor_thread, NULL, monitor_device, &monitor);
dpy = XOpenDisplay(NULL);
scr = DefaultScreen(dpy);
root = RootWindow(dpy, scr);
win = XCreateWindow(dpy, root,
0, 0, W, H, 0, DefaultDepth(dpy, scr),
InputOutput, CopyFromParent,
CWEventMask, &swa);
pix = XCreatePixmap(dpy, win, W, H, DefaultDepth(dpy, scr));
gc = XCreateGC(dpy, win, 0, NULL);
XMapWindow(dpy, win);
XPresentQueryExtension(dpy, &present_opcode, &present_event_base, &present_error_base);
XPresentSelectInput(dpy, win, PresentCompleteNotifyMask);
for (;;) {
XSetForeground(dpy, gc, v ? WhitePixel(dpy, scr) : BlackPixel(dpy, scr));
XFillRectangle(dpy, pix, gc, 0, 0, W, H);
XPresentPixmap(dpy, win, pix, ++serial,
None, None, 0, 0, None, None, None,
PresentOptionNone,
0,
0, 0, NULL, 0);
put = vid_clock();
XFlush(dpy);
got_event = false;
exposed = false;
while (!got_event) {
XGenericEventCookie *cookie = (void *) &ev;
XNextEvent(dpy, &ev);
if (XGetEventData(dpy, cookie)) {
if (cookie->extension == present_opcode &&
cookie->evtype == PresentCompleteNotify) {
XPresentCompleteNotifyEvent *ce = cookie->data;
if (ce->serial_number == serial) {
show = ce->ust * 1000;
got_event = true;
}
}
XFreeEventData(dpy, cookie);
} else {
switch (ev.type) {
case Expose:
if (ev.xexpose.count == 0)
exposed = true;
break;
}
}
}
if (!exposed) {
pthread_mutex_lock(&time_mutex);
for (;;) {
if (vid_value == v) {
got = vid_time[v];
break;
}
pthread_cond_wait (&time_cond, &time_mutex);
}
pthread_mutex_unlock(&time_mutex);
if (show >= put && got >= show) {
printf("%d delay put->show %f show->got %f\n", v,
(show - put) / 1e9,
(got - show) / 1e9);
} else {
printf("%d invalid\n", v);
}
}
v = 1-v;
nanosleep(&ts, NULL);
}
}
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