split main .ino fine into multiple sub files

pong_render.cpp

@@ -0,0 +1,26 @@
+#include <Arduino.h>
+
+#include "config.h"
+
+void render_matrix(byte frame[MATRIX_HEIGHT][MATRIX_WIDTH], int p1_start, int p2_start, int &need_refresh, int ball_x, int ball_y) {
+  if (!need_refresh) return;
+  need_refresh= 0;
+  // clear
+  for (int x=0; x < MATRIX_WIDTH; x++) {
+    for (int y=0; y < MATRIX_HEIGHT; y++) {
+      frame[y][x]= 0;
+    }
+  }
+  
+  // players coords
+  for (int i= p1_start; i < p1_start+BAR_LENGTH; i++) {
+    frame[i][0]= 1;
+  }
+  for (int i= p2_start; i < p2_start+BAR_LENGTH; i++) {
+    frame[i][MATRIX_WIDTH-1]= 1;
+  }
+  
+  // ball coords
+  frame[ball_y][ball_x]= 1;
+
+}