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/* This file is part of can2joy.
*
* can2joy is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License 2 as
* published by the Free Software Foundation.
* can2joy 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.
* You should have received a copy of the GNU General Public License
* along with can2joy. If not, see <http://www.gnu.org/licenses/>.
*/
#include <fcntl.h>
#include <linux/can.h>
#include <linux/can/raw.h>
#include <linux/input.h>
#include <linux/uinput.h>
#include <net/if.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#define MIN(x, y) ((x) < (y) ? (x) : (y))
#define MAX(x, y) ((x) > (y) ? (x) : (y))
static int init_can(char *ifname)
{
struct sockaddr_can addr;
struct ifreq ifr;
int fd_can;
/* Open CAN socket */
fd_can = socket(PF_CAN, SOCK_RAW, CAN_RAW);
if (fd_can < 0) {
perror("socket");
return fd_can;
}
/* Get CAN interfaces's index by name */
strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
if (ioctl(fd_can, SIOCGIFINDEX, &ifr) < 0) {
perror("SIOCGIFINDEX");
return -1;
}
/* Bind CAN interface by index */
memset(&addr, 0, sizeof(addr));
addr.can_family = AF_CAN;
addr.can_ifindex = ifr.ifr_ifindex;
if (bind(fd_can, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
perror("bind");
return -1;
}
return fd_can;
}
static int init_uinput()
{
struct uinput_user_dev uidev;
int fd_uinput;
/* Open uinput */
fd_uinput = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
if(fd_uinput < 0) {
perror("open (/dev/uinput)");
return fd_uinput;
}
/* Register push buttons A, B */
ioctl(fd_uinput, UI_SET_EVBIT, EV_KEY);
ioctl(fd_uinput, UI_SET_KEYBIT, BTN_TRIGGER);
ioctl(fd_uinput, UI_SET_KEYBIT, BTN_THUMB);
/* Register absolute axes X, Y */
ioctl(fd_uinput, UI_SET_EVBIT, EV_ABS);
ioctl(fd_uinput, UI_SET_ABSBIT, ABS_X);
ioctl(fd_uinput, UI_SET_ABSBIT, ABS_Y);
/* Create a virtual input device ID */
memset(&uidev, 0, sizeof(uidev));
strncpy(uidev.name, "can2joy", UINPUT_MAX_NAME_SIZE);
uidev.id.bustype = BUS_USB;
uidev.id.vendor = 0x1234;
uidev.id.product = 0xfedc;
uidev.id.version = 1;
write(fd_uinput, &uidev, sizeof(uidev));
/* Set min/max values for axes */
uidev.absmin[ABS_X] = 255;
uidev.absmax[ABS_X] = -256;
uidev.absmin[ABS_Y] = -1;
uidev.absmax[ABS_Y] = 1;
write(fd_uinput, &uidev, sizeof(uidev));
/* Let uinput rip */
ioctl(fd_uinput, UI_DEV_CREATE);
return fd_uinput;
}
static void receive_one(int fd_can, int fd_uinput)
{
struct can_frame frm;
struct sockaddr_can addr;
int ret;
socklen_t len;
struct input_event ev;
short wheel_pos;
memset(&ev, 0, sizeof(ev));
ret = recvfrom(fd_can, &frm, sizeof(struct can_frame), 0,
(struct sockaddr *)&addr, &len);
if (ret < 0) {
perror("recvfrom");
exit(1);
}
switch(frm.can_id) {
case 0x35b:
/* Check clutch and brake pedal.
* We only read one bit for each, so don't expect fine
* control of your simulated Lamborghini!
*/
ev.type = EV_KEY;
ev.code = BTN_TRIGGER;
ev.value = !(!(frm.data[4] & 3));
write(fd_uinput, &ev, sizeof(ev));
ev.code = BTN_THUMB;
ev.value = !(!(frm.data[6] & 4));
write(fd_uinput, &ev, sizeof(ev));
break;
case 0x3c3:
/* Translate absolute wheel position.
* It's a signed 16-bit integer in the first two bytes
* of a 0x3c3 frame, indicating how far it is turned.
* Zero means we're driving straight.
* The next two bytes are the angular speed of the wheel
* being turned, but we don't care about that here.
*/
wheel_pos = *((short*)(&frm.data[0]));
printf("Wheel position: %i\n", wheel_pos);
/* Clamp the wheel position around the zero point.
* This is to avoid excessive wear of the wheels of the
* parked car as well as of the whole steering mechanism.
*/
if (wheel_pos >= 0) {
wheel_pos = MIN(255, wheel_pos);
} else {
/* The first negative value next to zero is
* -32768. So we have to invert this to -1
* instead of -32768, -2 instead of -32767, etc.
*/
wheel_pos = 0 - (wheel_pos + 32768);
wheel_pos = MAX(-256, wheel_pos);
}
printf("Wheel position (clamped): %i\n", wheel_pos);
/* Report the change in wheel position as the X axis */
ev.type = EV_ABS;
ev.code = ABS_X;
ev.value = wheel_pos;
ret = write(fd_uinput, &ev, sizeof(ev));
/* Report a dummy Y axis for programs that expect it */
ev.code = ABS_Y;
ev.value = 0;
ret = write(fd_uinput, &ev, sizeof(ev));
break;
}
/* Flush the uinput events we just generated */
ev.type = EV_SYN;
ev.code = SYN_REPORT;
ev.value = 0;
write(fd_uinput, &ev, sizeof(ev));
}
int main(int argc, char **argv)
{
int fd_can;
int fd_uinput;
if (argc < 2) {
printf("Usage: %s <can-interface>\n", argv[0]);
printf("\n");
printf("Example: %s can0\n", argv[0]);
return 1;
}
fd_can = init_can(argv[1]);
if (fd_can < 0)
return 1;
fd_uinput = init_uinput();
if (fd_uinput < 0)
return 1;
for (;;)
receive_one(fd_can, fd_uinput);
ioctl(fd_uinput, UI_DEV_DESTROY);
return 0;
}
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