code cleanup + call clear rows when placing a block

src/game/tetromino/placing.c

@@ -1,13 +1,55 @@
 #include "placing.h"
 
 #include <stdint.h>
-#include <stdlib.h>
 
 #include "../../window/colour.h"
 #include "../game.h"
-#include "SDL_scancode.h"
 #include "shapes.h"
 
+
+static bool is_filled(CRow row) {
+    for (uint8_t x = 0; x < COLUMNS; x++) {
+        if (row[x].packed == NONE) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static inline void set_row(Row* rows, const uint8_t y, Row row) {
+    rows[(ROWS - 1) - y] = row;
+}
+
+static void clear_rows(Row* row) {
+    uint8_t filled_rows = 0;
+
+    // loop through each row
+    for (uint8_t y = 0; y < ROWS; y++) {
+        // zero out the row instead if we've reached the top rows
+        if ((ROWS - y) <= filled_rows) {
+            for (uint8_t x = 0; x < COLUMNS; x++)
+                row[filled_rows--][x].packed = 0; // use filled_rows as the y index and decrease them as we go.
+            continue;
+        }
+
+        // get the row we currently need to check
+        Row crow = filled_rows > 0
+                       ? row[y + filled_rows]
+                       : row[y];
+
+        // set the current y to the current row
+        Row row_cache = row[y];
+        set_row(row, y, crow);
+
+        if (!is_filled(crow)) continue;
+
+        // write the cached row to the top if we know that the current row pointer will be lost
+        row[filled_rows] = row_cache;
+        filled_rows++;
+    }
+}
+
 // sets a shape to the screen
 static void set_shape_i(Row* row, const ShapeId id, const uint8_t pos_x) {
     const Shape shape = shape_from_id(id);
@@ -59,6 +101,7 @@ void place_update(GameData* const game_data, const InputData move) {
         const uint8_t y = selected->y + 1;
         if (shape_intersects(game_data->row, selected->id, selected->x, y)) {
             set_shape(game_data->row, selected->id, selected->x, selected->y); // if the shape intersects vertically, write the shape at the current position and return
+            clear_rows(game_data->row);                                        // clear the rows that have been completed
             return;
         }