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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