+/* ?0SA 00DU, ?1CB RLDU */
+#define STATE_BYTES 2
+
+static uint8_t fixed_input_state[STATE_BYTES] = { 0x33, 0x3f };
+
+enum mdbtn {
+ MDBTN_UP = 1,
+ MDBTN_DOWN,
+ MDBTN_LEFT,
+ MDBTN_RIGHT,
+ MDBTN_A,
+ MDBTN_B,
+ MDBTN_C,
+ MDBTN_START,
+};
+
+static const enum mdbtn evdev_md_map[KEY_CNT] = {
+ [KEY_UP] = MDBTN_UP,
+ [KEY_DOWN] = MDBTN_DOWN,
+ [KEY_LEFT] = MDBTN_LEFT,
+ [KEY_RIGHT] = MDBTN_RIGHT,
+ [KEY_HOME] = MDBTN_A,
+ [KEY_PAGEDOWN] = MDBTN_B,
+ [KEY_END] = MDBTN_C,
+ [KEY_LEFTALT] = MDBTN_START,
+};
+
+int do_evdev_input(int fd)
+{
+ uint8_t old_state[STATE_BYTES];
+ uint8_t changed_bits[STATE_BYTES] = { 0, };
+ struct input_event ev;
+ enum mdbtn mdbtn;
+ int i, ret;
+
+ ret = read(fd, &ev, sizeof(ev));
+ if (ret != sizeof(ev)) {
+ fprintf(stderr, "evdev read %d/%zd: ", ret, sizeof(ev));
+ perror("");
+ return 0;
+ }
+
+ if (ev.type != EV_KEY)
+ return 0;
+
+ if (ev.value != 0 && ev.value != 1)
+ return 0;
+
+ if ((uint32_t)ev.code >= ARRAY_SIZE(evdev_md_map)) {
+ fprintf(stderr, "evdev read bad key: %u\n", ev.code);
+ return 0;
+ }
+
+ mdbtn = evdev_md_map[ev.code];
+ if (mdbtn == 0)
+ return 0;
+
+ memcpy(old_state, fixed_input_state, STATE_BYTES);
+
+ /* ?0SA 00DU, ?1CB RLDU */
+ switch (mdbtn) {
+ case MDBTN_UP:
+ changed_bits[0] = 0x01;
+ changed_bits[1] = 0x01;
+ break;
+ case MDBTN_DOWN:
+ changed_bits[0] = 0x02;
+ changed_bits[1] = 0x02;
+ break;
+ case MDBTN_LEFT:
+ changed_bits[0] = 0x00;
+ changed_bits[1] = 0x04;
+ break;
+ case MDBTN_RIGHT:
+ changed_bits[0] = 0x00;
+ changed_bits[1] = 0x08;
+ break;
+ case MDBTN_A:
+ changed_bits[0] = 0x10;
+ changed_bits[1] = 0x00;
+ break;
+ case MDBTN_B:
+ changed_bits[0] = 0x00;
+ changed_bits[1] = 0x10;
+ break;
+ case MDBTN_C:
+ changed_bits[0] = 0x00;
+ changed_bits[1] = 0x20;
+ break;
+ case MDBTN_START:
+ changed_bits[0] = 0x20;
+ changed_bits[1] = 0x00;
+ break;
+ }
+
+ if (ev.value) {
+ // key press
+ for (i = 0; i < STATE_BYTES; i++)
+ fixed_input_state[i] &= ~changed_bits[i];
+ }
+ else {
+ // key release
+ for (i = 0; i < STATE_BYTES; i++)
+ fixed_input_state[i] |= changed_bits[i];
+ }
+
+ return memcmp(old_state, fixed_input_state, STATE_BYTES) ? 1 : 0;
+}
+