Comply with MT syncronization protocol

The latest semantic clarifications in the kernel MT protocol allow
SYN_MT_REPORT to be sent without actually sending any finger data. Add
a mask to the hardware data so that the data actually read can be
tracked.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

3 files changed, 59 insertions, 21 deletions

diff --git a/src/hwdata.c b/src/hwdata.c
index 9e384dc..e76bcd8 100644
--- a/src/hwdata.c
+++ b/src/hwdata.c
@@ -26,17 +26,42 @@ void init_hwdata(struct HWData *hw)
 	memset(hw, 0, sizeof(struct HWData));
 }
 
+static void set_value(struct HWData *hw, int code, int value)
+{
+	if (hw->nread < DIM_FINGER) {
+		(&hw->finger[hw->nread].touch_major)[code] = value;
+		SETBIT(hw->mread[hw->nread], code);
+	}
+}
+
+static void accept_finger(struct HWData *hw)
+{
+	if (hw->nread < DIM_FINGER &&
+	    GETBIT(hw->mread[hw->nread], BIT_MT_POSITION_X) &&
+	    GETBIT(hw->mread[hw->nread], BIT_MT_POSITION_Y)) {
+		hw->mask[hw->nread] = hw->mread[hw->nread];
+		hw->nfinger = ++hw->nread;
+	}
+	if (hw->nread < DIM_FINGER)
+		hw->mread[hw->nread] = 0;
+}
+
+static void accept_packet(struct HWData *hw)
+{
+	hw->nread = 0;
+	hw->mread[hw->nread] = 0;
+}
+
 int read_hwdata(struct HWData *hw, const struct input_event* ev)
 {
 	switch (ev->type) {
 	case EV_SYN:
 		switch (ev->code) {
 		case SYN_REPORT:
-			hw->nread = 0;
+			accept_packet(hw);
 			return 1;
 		case SYN_MT_REPORT:
-			hw->nread++;
-			hw->nfinger = hw->nread;
+			accept_finger(hw);
 			break;
 		}
 		break;
@@ -63,32 +88,30 @@ int read_hwdata(struct HWData *hw, const struct input_event* ev)
 		}
 		break;
 	case EV_ABS:
-		if (hw->nread == DIM_FINGER)
-			break;
 		switch (ev->code) {
 		case ABS_MT_TOUCH_MAJOR:
-			hw->finger[hw->nread].touch_major = ev->value;
+			set_value(hw, BIT_MT_TOUCH_MAJOR, ev->value);
 			break;
 		case ABS_MT_TOUCH_MINOR:
-			hw->finger[hw->nread].touch_minor = ev->value;
+			set_value(hw, BIT_MT_TOUCH_MINOR, ev->value);
 			break;
 		case ABS_MT_WIDTH_MAJOR:
-			hw->finger[hw->nread].width_major = ev->value;
+			set_value(hw, BIT_MT_WIDTH_MAJOR, ev->value);
 			break;
 		case ABS_MT_WIDTH_MINOR:
-			hw->finger[hw->nread].width_minor = ev->value;
+			set_value(hw, BIT_MT_WIDTH_MINOR, ev->value);
 			break;
 		case ABS_MT_ORIENTATION:
-			hw->finger[hw->nread].orientation = ev->value;
+			set_value(hw, BIT_MT_ORIENTATION, ev->value);
 			break;
 		case ABS_MT_PRESSURE:
-			hw->finger[hw->nread].pressure = ev->value;
+			set_value(hw, BIT_MT_PRESSURE, ev->value);
 			break;
 		case ABS_MT_POSITION_X:
-			hw->finger[hw->nread].position_x = ev->value;
+			set_value(hw, BIT_MT_POSITION_X, ev->value);
 			break;
 		case ABS_MT_POSITION_Y:
-			hw->finger[hw->nread].position_y = ev->value;
+			set_value(hw, BIT_MT_POSITION_Y, ev->value);
 			break;
 		}
 		break;
diff --git a/src/hwdata.h b/src/hwdata.h
index 38ffc6b..aa589e0 100644
--- a/src/hwdata.h
+++ b/src/hwdata.h
@@ -34,6 +34,16 @@
 #define MT_BUTTON_HWHEEL_LEFT 5
 #define MT_BUTTON_HWHEEL_RIGHT 6
 
+#define BIT_MT_TOUCH_MAJOR 0
+#define BIT_MT_TOUCH_MINOR 1
+#define BIT_MT_WIDTH_MAJOR 2
+#define BIT_MT_WIDTH_MINOR 3
+#define BIT_MT_ORIENTATION 4
+#define BIT_MT_PRESSURE 5
+#define BIT_MT_POSITION_X 6
+#define BIT_MT_POSITION_Y 7
+#define BIT_MT_CNT 8
+
 struct FingerData {
 	int touch_major, touch_minor;
 	int width_major, width_minor;
@@ -41,8 +51,20 @@ struct FingerData {
 	int position_x, position_y;
 };
 
+/**
+ * struct HWData - hardware reads
+ *
+ * @finger: finger data
+ * @mask: bits corresponding to data actually read (readonly)
+ * @mread: bits corresponding to data in progress (writeonly)
+ * @button: bitmask of buttons
+ * @nfinger: number of fingers actually read (readonly)
+ * @nread: number of fingers in progress (writeonly)
+ *
+ */
 struct HWData {
 	struct FingerData finger[DIM_FINGER];
+	unsigned mask[DIM_FINGER], mread[DIM_FINGER];
 	unsigned button;
 	int nfinger, nread;
 };
diff --git a/src/state.c b/src/state.c
index 774828a..31eca70 100644
--- a/src/state.c
+++ b/src/state.c
@@ -36,16 +36,9 @@ static int fincmp(const void *a, const void *b)
 	return ((struct FingerState *)a)->id - ((struct FingerState *)b)->id;
 }
 
-/* seander@cs.stanford.edu */
-inline unsigned abs32(int x)
-{
-	int const m = x >> 31;
-	return (x + m) ^ m;
-}
-
 inline int abs15(int x)
 {
-	return 32767 & abs32(x);
+	return 32767 & (x < 0 ? -x : x);
 }
 
 /* abslute scale is assumed to fit in 15 bits */