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124 lines
2.7 KiB
124 lines
2.7 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <sys/poll.h>
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#include <linux/input.h>
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#include "touch.h"
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/* this macro is used to tell if "bit" is set in "array"
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* it selects a byte from the array, and does a boolean AND
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* operation with a byte that only has the relevant bit set.
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* eg. to check for the 12th bit, we do (array[1] & 1<<4)
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*/
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#define test_bit(bit, array) (array[bit/8] & (1<<(bit%8)))
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static int find_dev() {
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int err;
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int ret = -1;
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DIR *dir = opendir("/dev/input");
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assert(dir);
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struct dirent* de = NULL;
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while ((de = readdir(dir))) {
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if (strncmp(de->d_name, "event", 5)) continue;
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int fd = openat(dirfd(dir), de->d_name, O_RDONLY);
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assert(fd >= 0);
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unsigned char ev_bits[KEY_MAX / 8 + 1];
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err = ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(ev_bits)), ev_bits);
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assert(err >= 0);
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if (test_bit(ABS_MT_POSITION_X, ev_bits) && test_bit(ABS_MT_POSITION_Y, ev_bits)) {
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ret = fd;
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break;
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}
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close(fd);
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}
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closedir(dir);
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return ret;
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}
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void touch_init(TouchState *s) {
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s->fd = find_dev();
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assert(s->fd >= 0);
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}
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int touch_poll(TouchState *s, int* out_x, int* out_y, int timeout) {
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assert(out_x && out_y);
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bool up = false;
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while (true) {
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struct pollfd polls[] = {{
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.fd = s->fd,
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.events = POLLIN,
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}};
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int err = poll(polls, 1, timeout);
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if (err < 0) {
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return -1;
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}
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if (!(polls[0].revents & POLLIN)) {
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break;
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}
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struct input_event event;
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err = read(polls[0].fd, &event, sizeof(event));
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if (err < sizeof(event)) {
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return -1;
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}
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switch (event.type) {
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case EV_ABS:
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if (event.code == ABS_MT_POSITION_X) {
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s->last_x = event.value;
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} else if (event.code == ABS_MT_POSITION_Y) {
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s->last_y = event.value;
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} else if (event.code == ABS_MT_TRACKING_ID && event.value != -1) {
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up = true;
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}
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break;
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default:
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break;
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}
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}
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if (up) {
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// adjust for flippening
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*out_x = s->last_y;
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*out_y = 1080 - s->last_x;
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}
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return up;
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}
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int touch_read(TouchState *s, int* out_x, int* out_y) {
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assert(out_x && out_y);
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struct input_event event;
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int err = read(s->fd, &event, sizeof(event));
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if (err < sizeof(event)) {
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return -1;
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}
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bool up = false;
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switch (event.type) {
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case EV_ABS:
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if (event.code == ABS_MT_POSITION_X) {
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s->last_x = event.value;
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} else if (event.code == ABS_MT_POSITION_Y) {
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s->last_y = event.value;
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}
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up = true;
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break;
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default:
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break;
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}
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if (up) {
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// adjust for flippening
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*out_x = s->last_y;
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*out_y = 1080 - s->last_x;
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}
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return up;
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}
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