====== Step 3.3: Coding the loops ======

If you remember the flow chart from [[tutorial1-tetris:step2.4|Step 2.4]], there we designed the program flow in several loops that are nested into one another.

  * The inner loop, reponsive for moving the current piece in the playfield, let's call it the //update loop//. One iteration in this loop is one downward movement of a piece.
  * The middle loop, or the //game loop//, which is looping during the gameplay. It is responsive for "sending" the pieces after one another. One iteration within this loop is one piece falling down. 
  * The outer loop, the //program loop//. One iteration within this loop is a game.

Here is how the three loops are nested (in pseudo code):

  REM program loop
  WHILE <true>
    <player presses fire>
    <initialize game variables>
    REM game loop
    REPEAT
      <put new piece at top>
      REM update loop
      REPEAT
        <move piece>
      UNTIL <piece hits bottom>
      <clear rows>
      <update score>
    UNTIL <game over>
    <update hiscore>
  ENDWHILE

The actual code will follow the idea of the above pseudo-code.

I suggest we start with the update loop on the next page.

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