project for a (works on my devices) demo

sources/input/touch/touch_controller_L3_deltas_compute.c

@@ -0,0 +1,110 @@
+#include "../../../headers/input/touch/touch_controller_L3_deltas_compute.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+
+void delta_store( 
+	tracked_delta *delta, uint8_t state_flag, uint8_t cursor, uint64_t *ids_buffer
+){
+	(*delta).state = state_flag;
+	(*delta).tracking_id = ids_buffer[cursor];
+}
+
+void increase_and_flag( 
+	uint8_t *cursor, uint8_t buffer_length, uint8_t *buffer_completed
+){
+	(*cursor)++;
+
+	if( (*cursor) >= buffer_length){
+		*buffer_completed = 1;
+	}
+}
+
+/*	a lot of params since sizeof(arr) does not work with heap arrays */
+/*	takes two sorted arrays of ids : previous and current
+	returns an array of tracked_delta(s)
+*/
+void touch_events_sorted_ids_deltas( 
+	tracked_delta **endbuffer, uint16_t *endcount, 
+	uint64_t *previous_ids, uint8_t previous_count, 
+	uint64_t *current_ids, uint8_t current_count
+){
+	uint16_t accumulatedCounter = 0;
+
+	uint8_t previous_completed = 0;
+	uint8_t current_completed = 0;
+
+	uint8_t previous_cursor = 0;
+	uint8_t current_cursor = 0;
+
+	//until at least one of the lists has not been fully traversed, checks must be done to avoid collisions
+	while( ! previous_completed && ! current_completed){
+
+		accumulatedCounter++;
+
+		if( previous_ids[previous_cursor] < current_ids[current_cursor]){
+			increase_and_flag(  &previous_cursor, previous_count, &previous_completed);
+		}
+		else if( previous_ids[previous_cursor] == current_ids[current_cursor]){
+			increase_and_flag(  &previous_cursor, previous_count, &previous_completed);
+			increase_and_flag(  &current_cursor, current_count, &current_completed);
+		}
+		else{
+			increase_and_flag(  &current_cursor, current_count, &current_completed);
+		}
+	}
+
+	accumulatedCounter += ( previous_count - previous_cursor);
+	accumulatedCounter += ( current_count - current_cursor);
+	
+	*endcount = accumulatedCounter;
+	
+	*endbuffer = malloc( *endcount * sizeof( tracked_delta));
+
+	/* since the scan has already been done once, previous_completed and current_completed could be substituted by a counter_threshold variable... */
+	accumulatedCounter = (uint16_t) -1u;
+
+	previous_completed = 0;
+	current_completed = 0;
+
+	previous_cursor = 0;
+	current_cursor = 0;
+
+	while( ! previous_completed && ! current_completed){
+
+		accumulatedCounter++;
+
+		if( previous_ids[previous_cursor] < current_ids[current_cursor]){
+			endbuffer[accumulatedCounter]->old_index = previous_cursor;
+			delta_store( endbuffer[accumulatedCounter], TRACKED_DELTA_EXITED, previous_cursor, previous_ids);
+			increase_and_flag(  &previous_cursor, previous_count, &previous_completed);
+		}
+		else if( previous_ids[previous_cursor] == current_ids[current_cursor]){
+			endbuffer[accumulatedCounter]->old_index = previous_cursor;
+			endbuffer[accumulatedCounter]->new_index = current_cursor;
+			// both the combinations of cursor and ids_buffer will work
+			delta_store( endbuffer[accumulatedCounter], TRACKED_DELTA_UNCHANGED, previous_cursor, previous_ids);
+			increase_and_flag(  &previous_cursor, previous_count, &previous_completed);
+			increase_and_flag(  &current_cursor, current_count, &current_completed);
+		}
+		else{
+			endbuffer[accumulatedCounter]->new_index = current_cursor;
+			delta_store( endbuffer[accumulatedCounter], TRACKED_DELTA_ENTERED, current_cursor, current_ids );
+			increase_and_flag(  &current_cursor, current_count, &current_completed);
+		}
+	}
+
+	while( ! previous_completed){
+		accumulatedCounter++;
+		endbuffer[accumulatedCounter]->old_index = previous_cursor;
+		delta_store( endbuffer[accumulatedCounter], TRACKED_DELTA_EXITED, previous_cursor, previous_ids);
+		increase_and_flag(  &previous_cursor, previous_count, &previous_completed);
+	}
+
+	while( ! current_completed){
+		accumulatedCounter++;
+		endbuffer[accumulatedCounter]->new_index = current_cursor;
+		delta_store( endbuffer[accumulatedCounter], TRACKED_DELTA_ENTERED, current_cursor, current_ids );
+		increase_and_flag(  &current_cursor, current_count, &current_completed);
+	}
+}