copy moving white lines into framebuffer

src/sender.zig

@@ -85,7 +85,8 @@ pub fn main() !void {
     var frame_count: i32 = 0;
     var bytes: i32 = 0;
 
-    const two_lines = try allocator.alloc(u8, stride * 2);
+    const two_lines_len = stride * 2;
+    const two_lines = try allocator.alloc(u8, two_lines_len);
     defer allocator.free(two_lines);
 
     @memset(two_lines, 255);
@@ -95,7 +96,9 @@ pub fn main() !void {
     while (frame_count < 10000) : (frame_count += 1) {
         @memcpy(frame_buffer, content);
 
-        // TODO: copy the white line over here
+        const two_lines_slice = frame_buffer[line_position..(line_position + two_lines_len)];
+        @memcpy(two_lines_slice, two_lines[0..two_lines_len]);
+
         line_position += stride * 2;
         if (line_position >= video_frame.DataLength) {
             line_position = 0;