rework how acceleration works and avoid acceleration influencing raw mickey counts (as given to e.g. windows)HEADmaster

2 files changed, 32 insertions, 26 deletions

diff --git a/mousetsr.c b/mousetsr.c
index 8990e4d..16c84df 100644
--- a/mousetsr.c
+++ b/mousetsr.c
@@ -629,33 +629,41 @@ static void handle_mouse_event(uint16_t buttons, bool absolute, int x, int y, ch
 		}
 	} else if (x || y) {
 		// Relative movement: x,y are in mickeys
-		uint16_t ticks = bda_get_tick_count_lo();
+		uint16_t cur_ticks = bda_get_tick_count_lo();
 		unsigned ax = abs(x), ay = abs(y);
 
 		events |= INT33_EVENT_MASK_MOVEMENT;
 
-		// Check if around one second has passed
-		if ((ticks - data.last_motion_ticks) >= 18) {
+		// Check if a tick has passed, if so update speed
+		if (data.last_motion_ticks != cur_ticks) {
+			uint16_t elapsed_ticks = cur_ticks - data.last_motion_ticks;
+			data.cur_speed = (data.total_motion / elapsed_ticks) * 18; // Extrapolate speed from movement in this tick
+#if TRACE_EVENTS
+			dprintf("mouse speed = %u / threshold = %u  total_motion in last %u ticks = %u\n", data.cur_speed, data.doubleSpeedThreshold * data.doubleSpeedThreshold, elapsed_ticks, data.total_motion);
+#endif
 			data.total_motion = 0;
-			data.last_motion_ticks = ticks;
+			data.last_motion_ticks = cur_ticks;
 		}
-
-		// If more than the double speed threshold has been moved in the last second,
-		// double the speed
 		data.total_motion += ax * ax + ay * ay;
-		if (data.total_motion > data.doubleSpeedThreshold * data.doubleSpeedThreshold) {
-			x *= 2;
-			y *= 2;
-		}
 
+		// Update the raw mickey counters
 		data.delta.x += x;
 		data.delta.y += y;
-		data.delta_frac.x = 0;
-		data.delta_frac.y = 0;
+
+		// Invalidate last abs position
 		data.abs_pos.x = -1;
 		data.abs_pos.y = -1;
 
-		// Convert mickeys into pixels
+		// Convert mickeys into pixels, applying speed, sensitivity and acceleration
+
+		// If more than the double speed threshold has been moved in the last second,
+		// double the speed
+		if (data.cur_speed > data.doubleSpeedThreshold * data.doubleSpeedThreshold) {
+			x *= 2;
+			y *= 2;
+		}
+
+		// Apply mickeysPerLine. Keep the fractional part for the next movement!
 		data.pos.x += scalei_rem(x, data.mickeysPerLine.x, 8, &data.pos_frac.x);
 		data.pos.y += scalei_rem(y, data.mickeysPerLine.y, 8, &data.pos_frac.y);
 	}
@@ -1190,11 +1198,12 @@ static void reset_mouse_state()
 	data.pos_frac.y = 0;
 	data.delta.x = 0;
 	data.delta.y = 0;
-	data.delta_frac.x = 0;
-	data.delta_frac.y = 0;
 	data.abs_pos.x = -1;
 	data.abs_pos.y = -1;
 	data.buttons = 0;
+	data.cur_speed = 0;
+	data.total_motion = 0;
+	data.last_motion_ticks = bda_get_tick_count_lo();
 	for (i = 0; i < MAX_BUTTONS; i++) {
 		data.button[i].pressed.count = 0;
 		data.button[i].pressed.last.x = 0;
@@ -1311,8 +1320,6 @@ static void int33_handler(union INTPACK r)
 		data.pos_frac.y = 0;
 		data.delta.x = 0;
 		data.delta.y = 0;
-		data.delta_frac.x = 0;
-		data.delta_frac.y = 0;
 		bound_position_to_window();
 		break;
 	case INT33_GET_BUTTON_PRESSED_COUNTER:
diff --git a/mousetsr.h b/mousetsr.h
index 704f670..9b8fdf8 100644
--- a/mousetsr.h
+++ b/mousetsr.h
@@ -159,10 +159,10 @@ typedef struct tsrdata {
 	uint8_t port_irq;
 
 	// Current mouse settings
-	/** Mouse sensitivity/speed. */
-	struct point mickeysPerLine; // mickeys per 8 pixels
-	/** Mouse acceleration "double-speed threshold". */
-	uint16_t doubleSpeedThreshold; // mickeys
+	/** Mouse speed, in mickeys per "line" (aka 8 pixels). */
+	struct point mickeysPerLine;
+	/** Mouse acceleration "double-speed threshold", in mickeys per second. */
+	uint16_t doubleSpeedThreshold;
 	/** Current window min coordinates. */
 	struct point min;
 	/** Current window max coordinates. */
@@ -191,12 +191,11 @@ typedef struct tsrdata {
 	struct point pos_frac;
 	/** Current delta movement (in mickeys) since the last report. */
 	struct point delta;
-	/** Current remainder of delta movement that does not yet translate to an entire mickey
-	 *  Usually only when mickeysPerLine is not a multiple of 8. */
-	struct point delta_frac;
 	/** Last absolute position (to compute a delta for relative motion emulation). Using -1 for "none". */
 	struct point abs_pos;
-	/** Total mickeys moved in the last second. */
+	/** Current calculated mouse speed (in mickeys/second) */
+	uint16_t cur_speed;
+	/** Total mickeys moved in the last tick. */
 	uint16_t total_motion;
 	/** Ticks when the above value was last reset. */
 	uint16_t last_motion_ticks;