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- /* Copyright 2022 Daniel Kao <daniel.m.kao@gmail.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.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
- #include <string.h>
- #include "pointing_device_gestures.h"
- #include "timer.h"
-
- #ifdef POINTING_DEVICE_GESTURES_CURSOR_GLIDE_ENABLE
- # ifdef POINTING_DEVICE_MOTION_PIN
- # error POINTING_DEVICE_MOTION_PIN not supported when using inertial cursor. Need repeated calls to get_report() to generate glide events.
- # endif
-
- static void cursor_glide_stop(cursor_glide_context_t* glide) {
- memset(&glide->status, 0, sizeof(glide->status));
- }
-
- static cursor_glide_t cursor_glide(cursor_glide_context_t* glide) {
- cursor_glide_status_t* status = &glide->status;
- cursor_glide_t report;
- int32_t p;
- int32_t x, y;
-
- if (status->v0 == 0) {
- report.dx = 0;
- report.dy = 0;
- report.valid = false;
- cursor_glide_stop(glide);
- goto exit;
- }
-
- status->counter++;
- /* Calculate current 1D position */
- p = status->v0 * status->counter - (int32_t)glide->config.coef * status->counter * status->counter / 2;
- /*
- * Translate to x & y axes
- * Done this way instead of applying friction to each axis separately, so we don't end up with the shorter axis stuck at 0 towards the end of diagonal movements.
- */
- x = (int32_t)(p * status->dx0 / status->v0);
- y = (int32_t)(p * status->dy0 / status->v0);
- report.dx = (mouse_xy_report_t)(x - status->x);
- report.dy = (mouse_xy_report_t)(y - status->y);
- report.valid = true;
- if (report.dx <= 1 && report.dx >= -1 && report.dy <= 1 && report.dy >= -1) {
- /* Stop gliding once speed is low enough */
- cursor_glide_stop(glide);
- goto exit;
- }
- status->x = x;
- status->y = y;
- status->timer = timer_read();
-
- exit:
- return report;
- }
-
- cursor_glide_t cursor_glide_check(cursor_glide_context_t* glide) {
- cursor_glide_t invalid_report = {0, 0, false};
- cursor_glide_status_t* status = &glide->status;
-
- if (status->z || (status->dx0 == 0 && status->dy0 == 0) || timer_elapsed(status->timer) < glide->config.interval) {
- return invalid_report;
- } else {
- return cursor_glide(glide);
- }
- }
-
- static inline uint16_t sqrt32(uint32_t x) {
- uint32_t l, m, h;
-
- if (x == 0) {
- return 0;
- } else if (x > (UINT16_MAX >> 2)) {
- /* Safe upper bound to avoid integer overflow with m * m */
- h = UINT16_MAX;
- } else {
- /* Upper bound based on closest log2 */
- h = (1 << (((__builtin_clzl(1) - __builtin_clzl(x) + 1) + 1) >> 1));
- }
- /* Lower bound based on closest log2 */
- l = (1 << ((__builtin_clzl(1) - __builtin_clzl(x)) >> 1));
-
- /* Binary search to find integer square root */
- while (l != h - 1) {
- m = (l + h) / 2;
- if (m * m <= x) {
- l = m;
- } else {
- h = m;
- }
- }
- return l;
- }
-
- cursor_glide_t cursor_glide_start(cursor_glide_context_t* glide) {
- cursor_glide_t invalid_report = {0, 0, false};
- cursor_glide_status_t* status = &glide->status;
-
- status->timer = timer_read();
- status->counter = 0;
- status->v0 = (status->dx0 == 0 && status->dy0 == 0) ? 0.0 : sqrt32(((int32_t)status->dx0 * 256 * status->dx0 * 256) + ((int32_t)status->dy0 * 256 * status->dy0 * 256)); // skip trigonometry if not needed, calculate distance in Q8
- status->x = 0;
- status->y = 0;
- status->z = 0;
-
- if (status->v0 < ((uint32_t)glide->config.trigger_px * 256)) { /* Q8 comparison */
- /* Not enough velocity to be worth gliding, abort */
- cursor_glide_stop(glide);
- return invalid_report;
- }
-
- return cursor_glide(glide);
- }
-
- void cursor_glide_update(cursor_glide_context_t* glide, mouse_xy_report_t dx, mouse_xy_report_t dy, uint16_t z) {
- cursor_glide_status_t* status = &glide->status;
-
- status->dx0 = dx;
- status->dy0 = dy;
- status->z = z;
- }
- #endif
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