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/* Simple example of how to use libuEv with Linux joystick API
*
* Copyright (c) 2014-2024 Joachim Wiberg <troglobit()gmail!com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <fcntl.h>
#include <unistd.h>
#include "uev.h"
struct js_event {
uint32_t time; /* event timestamp in milliseconds */
int16_t value; /* value */
uint8_t type; /* event type */
uint8_t number; /* axis/button number */
} e;
/*
* Always check for UEV_ERROR in watcher callback!
* Possibly joystick was unplugged
*/
static void joystick_cb(uev_t *w, void *arg, int events)
{
ssize_t len;
if (UEV_ERROR == events) {
warnx("Spurious problem with the joystick watcher, restarting.");
uev_io_start(w);
}
len = read(w->fd, &e, sizeof(e));
if (len < 0) {
warn("Failed reading joystick event");
return;
}
if (len == 0 || UEV_HUP == events) {
warn("Joystick disconnected");
return;
}
switch (e.type) {
case 1:
printf("Button %d %s\n", e.number, e.value ? "pressed" : "released");
break;
case 2:
printf("Joystick axis %d moved, value %d!\n", e.number, e.value);
break;
}
}
int main(void)
{
uev_ctx_t ctx;
uev_t js1;
int fd;
fd = open("/dev/input/js0", O_RDONLY, O_NONBLOCK);
if (fd < 0)
errx(errno, "Cannot find a joystick attached.");
uev_init(&ctx);
uev_io_init(&ctx, &js1, joystick_cb, NULL, fd, UEV_READ);
puts("Starting, press Ctrl-C to exit.");
return uev_run(&ctx, 0);
}
/**
* Local Variables:
* compile-command: "make joystick"
* indent-tabs-mode: t
* c-file-style: "linux"
* End:
*/
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