drivers/input/mouse/alps.c

Source file repositories/reference/linux-study-clean/drivers/input/mouse/alps.c

File Facts

System
Linux kernel
Corpus path
drivers/input/mouse/alps.c
Extension
.c
Size
88985 bytes
Lines
3237
Domain
Driver Families
Bucket
drivers/input
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (bit) {
			if (!prev_bit) {
				point->start_bit = i;
				point->num_bits = 0;
				(*fingers)++;
			}
			point->num_bits++;
		} else {
			if (prev_bit)
				point = high;
		}
		prev_bit = bit;
	}
}

/*
 * Process bitmap data from semi-mt protocols. Returns the number of
 * fingers detected. A return value of 0 means at least one of the
 * bitmaps was empty.
 *
 * The bitmaps don't have enough data to track fingers, so this function
 * only generates points representing a bounding box of all contacts.
 * These points are returned in fields->mt when the return value
 * is greater than 0.
 */
static int alps_process_bitmap(struct alps_data *priv,
			       struct alps_fields *fields)
{
	int i, fingers_x = 0, fingers_y = 0, fingers, closest;
	struct alps_bitmap_point x_low = {0,}, x_high = {0,};
	struct alps_bitmap_point y_low = {0,}, y_high = {0,};
	struct input_mt_pos corner[4];

	if (!fields->x_map || !fields->y_map)
		return 0;

	alps_get_bitmap_points(fields->x_map, &x_low, &x_high, &fingers_x);
	alps_get_bitmap_points(fields->y_map, &y_low, &y_high, &fingers_y);

	/*
	 * Fingers can overlap, so we use the maximum count of fingers
	 * on either axis as the finger count.
	 */
	fingers = max(fingers_x, fingers_y);

	/*
	 * If an axis reports only a single contact, we have overlapping or
	 * adjacent fingers. Divide the single contact between the two points.
	 */
	if (fingers_x == 1) {
		i = (x_low.num_bits - 1) / 2;
		x_low.num_bits = x_low.num_bits - i;
		x_high.start_bit = x_low.start_bit + i;
		x_high.num_bits = max(i, 1);
	}
	if (fingers_y == 1) {
		i = (y_low.num_bits - 1) / 2;
		y_low.num_bits = y_low.num_bits - i;
		y_high.start_bit = y_low.start_bit + i;
		y_high.num_bits = max(i, 1);
	}

	/* top-left corner */
	corner[0].x =
		(priv->x_max * (2 * x_low.start_bit + x_low.num_bits - 1)) /
		(2 * (priv->x_bits - 1));
	corner[0].y =
		(priv->y_max * (2 * y_low.start_bit + y_low.num_bits - 1)) /
		(2 * (priv->y_bits - 1));

	/* top-right corner */
	corner[1].x =
		(priv->x_max * (2 * x_high.start_bit + x_high.num_bits - 1)) /
		(2 * (priv->x_bits - 1));
	corner[1].y =
		(priv->y_max * (2 * y_low.start_bit + y_low.num_bits - 1)) /
		(2 * (priv->y_bits - 1));

	/* bottom-right corner */
	corner[2].x =
		(priv->x_max * (2 * x_high.start_bit + x_high.num_bits - 1)) /
		(2 * (priv->x_bits - 1));
	corner[2].y =
		(priv->y_max * (2 * y_high.start_bit + y_high.num_bits - 1)) /
		(2 * (priv->y_bits - 1));

	/* bottom-left corner */
	corner[3].x =
		(priv->x_max * (2 * x_low.start_bit + x_low.num_bits - 1)) /
		(2 * (priv->x_bits - 1));

Annotation

Implementation Notes