QMK mouse key: separate x/y accelerations

qmk_separate_mk_acc.diff

diff --git a/quantum/mousekey.c b/quantum/mousekey.c
index df8aa613be..7e451c517a 100644
--- a/quantum/mousekey.c
+++ b/quantum/mousekey.c
@@ -35,7 +35,8 @@ static inline int8_t times_inv_sqrt2(int8_t x) {
 static report_mouse_t mouse_report = {0};
 static void           mousekey_debug(void);
 static uint8_t        mousekey_accel        = 0;
-static uint8_t        mousekey_repeat       = 0;
+static uint8_t        mousekey_repeat_x     = 0;
+static uint8_t        mousekey_repeat_y     = 0;
 static uint8_t        mousekey_wheel_repeat = 0;
 #ifdef MOUSEKEY_INERTIA
 static uint8_t mousekey_frame     = 0; // track whether gesture is inactive, first frame, or repeating
@@ -87,7 +88,7 @@ uint8_t mk_wheel_time_to_max = MOUSEKEY_WHEEL_TIME_TO_MAX;
 
 /* Default accelerated mode */
 
-static uint8_t move_unit(void) {
+static uint8_t move_unit(uint8_t repeat) {
     uint16_t unit;
     if (mousekey_accel & (1 << 0)) {
         unit = (MOUSEKEY_MOVE_DELTA * mk_max_speed) / 4;
@@ -95,12 +96,12 @@ static uint8_t move_unit(void) {
         unit = (MOUSEKEY_MOVE_DELTA * mk_max_speed) / 2;
     } else if (mousekey_accel & (1 << 2)) {
         unit = (MOUSEKEY_MOVE_DELTA * mk_max_speed);
-    } else if (mousekey_repeat == 0) {
+    } else if (repeat == 0) {
         unit = MOUSEKEY_MOVE_DELTA;
-    } else if (mousekey_repeat >= mk_time_to_max) {
+    } else if (repeat >= mk_time_to_max) {
         unit = MOUSEKEY_MOVE_DELTA * mk_max_speed;
     } else {
-        unit = (MOUSEKEY_MOVE_DELTA * mk_max_speed * mousekey_repeat) / mk_time_to_max;
+        unit = (MOUSEKEY_MOVE_DELTA * mk_max_speed * repeat) / mk_time_to_max;
     }
     return (unit > MOUSEKEY_MOVE_MAX ? MOUSEKEY_MOVE_MAX : (unit == 0 ? 1 : unit));
 }
@@ -325,10 +326,12 @@ void mousekey_task(void) {
 
 #    else // default acceleration
 
-    if ((tmpmr.x || tmpmr.y) && timer_elapsed(last_timer_c) > (mousekey_repeat ? mk_interval : mk_delay * 10)) {
-        if (mousekey_repeat != UINT8_MAX) mousekey_repeat++;
-        if (tmpmr.x != 0) mouse_report.x = move_unit() * ((tmpmr.x > 0) ? 1 : -1);
-        if (tmpmr.y != 0) mouse_report.y = move_unit() * ((tmpmr.y > 0) ? 1 : -1);
+    if ((tmpmr.x && timer_elapsed(last_timer_c) > (mousekey_repeat_x ? mk_interval : mk_delay * 10)) ||
+        (tmpmr.y && timer_elapsed(last_timer_c) > (mousekey_repeat_y ? mk_interval : mk_delay * 10))) {
+        if (tmpmr.x != 0) mouse_report.x = move_unit(mousekey_repeat_x) * ((tmpmr.x > 0) ? 1 : -1);
+        if (tmpmr.y != 0) mouse_report.y = move_unit(mousekey_repeat_y) * ((tmpmr.y > 0) ? 1 : -1);
+        if (tmpmr.x && mousekey_repeat_x != UINT8_MAX) mousekey_repeat_x++;
+        if (tmpmr.y && mousekey_repeat_y != UINT8_MAX) mousekey_repeat_y++;
 
         /* diagonal move [1/sqrt(2)] */
         if (mouse_report.x && mouse_report.y) {
@@ -346,9 +349,9 @@ void mousekey_task(void) {
 #    endif // MOUSEKEY_INERTIA or not
 
     if ((tmpmr.v || tmpmr.h) && timer_elapsed(last_timer_w) > (mousekey_wheel_repeat ? mk_wheel_interval : mk_wheel_delay * 10)) {
-        if (mousekey_wheel_repeat != UINT8_MAX) mousekey_wheel_repeat++;
         if (tmpmr.v != 0) mouse_report.v = wheel_unit() * ((tmpmr.v > 0) ? 1 : -1);
         if (tmpmr.h != 0) mouse_report.h = wheel_unit() * ((tmpmr.h > 0) ? 1 : -1);
+        if (mousekey_wheel_repeat != UINT8_MAX) mousekey_wheel_repeat++;
 
         /* diagonal move [1/sqrt(2)] */
         if (mouse_report.v && mouse_report.h) {
@@ -390,14 +393,19 @@ void mousekey_on(uint8_t code) {
 
 #    else // no inertia
 
-    if (code == KC_MS_UP)
-        mouse_report.y = move_unit() * -1;
-    else if (code == KC_MS_DOWN)
-        mouse_report.y = move_unit();
-    else if (code == KC_MS_LEFT)
-        mouse_report.x = move_unit() * -1;
-    else if (code == KC_MS_RIGHT)
-        mouse_report.x = move_unit();
+    if (code == KC_MS_UP) {
+        if (mouse_report.y >= 0) mousekey_repeat_y = 0;
+        mouse_report.y = move_unit(mousekey_repeat_y) * -1;
+    } else if (code == KC_MS_DOWN) {
+        if (mouse_report.y <= 0) mousekey_repeat_y = 0;
+        mouse_report.y = move_unit(mousekey_repeat_y);
+    } else if (code == KC_MS_LEFT) {
+        if (mouse_report.x >= 0) mousekey_repeat_x = 0;
+        mouse_report.x = move_unit(mousekey_repeat_x) * -1;
+    } else if (code == KC_MS_RIGHT) {
+        if (mouse_report.x <= 0) mousekey_repeat_x = 0;
+        mouse_report.x = move_unit(mousekey_repeat_x);
+    }
 
 #    endif // inertia or not
 
@@ -461,12 +469,12 @@ void mousekey_off(uint8_t code) {
         mousekey_accel &= ~(1 << 1);
     else if (code == KC_MS_ACCEL2)
         mousekey_accel &= ~(1 << 2);
-    if (mouse_report.x == 0 && mouse_report.y == 0) {
-        mousekey_repeat = 0;
+    if (mouse_report.x == 0) mousekey_repeat_x = 0;
+    if (mouse_report.y == 0) mousekey_repeat_y = 0;
 #    ifdef MK_KINETIC_SPEED
+    if (mouse_report.x == 0 && mouse_report.y == 0)
         mouse_timer = 0;
 #    endif /* #ifdef MK_KINETIC_SPEED */
-    }
     if (mouse_report.v == 0 && mouse_report.h == 0) mousekey_wheel_repeat = 0;
 }
 
@@ -613,7 +621,8 @@ void mousekey_send(void) {
 
 void mousekey_clear(void) {
     mouse_report          = (report_mouse_t){};
-    mousekey_repeat       = 0;
+    mousekey_repeat_x     = 0;
+    mousekey_repeat_y     = 0;
     mousekey_wheel_repeat = 0;
     mousekey_accel        = 0;
 #ifdef MOUSEKEY_INERTIA