Main loop: Main game loop (Part 6 of 6)

       Name: Main game loop (Part 6 of 6)                            [Show more]
       Type: Subroutine
   Category: Main loop
    Summary: Process non-flight key presses (red function keys, docked keys)
  Deep dive: Program flow of the main game loop
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BAY calls via FRCE
             * TT219 calls via FRCE


 This is the second half of the minimal game loop, which we iterate when we are
 docked. This section covers the following:

   * Process more key presses (red function keys, docked keys etc.)

 It also supports joining the main loop with a key already "pressed", so we can
 jump into the main game loop to perform a specific action. In practice, this
 is used when we enter the docking bay in BAY to display Status Mode (red key
 f8), and when we finish buying or selling cargo in BAY2 to jump to the
 Inventory (red key f9).


 Other entry points:

   FRCE                 The entry point for the main game loop if we want to
                        jump straight to a specific screen, by pretending to
                        "press" a key, in which case A contains the internal key
                        number of the key we want to "press"


.FRCE

 JSR TT102              \ Call TT102 to process the key pressed in A

 LDA QQ12               \ Fetch the docked flag from QQ12 into A

 BNE MLOOP              \ If we are docked, loop back up to MLOOP just above
                        \ to restart the main loop, but skipping all the flight
                        \ and spawning code in the top part of the main loop

 JMP TT100              \ Otherwise jump to TT100 to restart the main loop from
                        \ the start