Main loop: Main game loop (Part 1 of 6)

       Name: Main game loop (Part 1 of 6)                            [Show more]
       Type: Subroutine
   Category: Main loop
    Summary: Spawn a trader (a peaceful Cobra Mk III)
  Deep dive: Program flow of the main game loop
             Ship data blocks
    Context: See this subroutine in context in the source code
 Variations: See code variations for this subroutine in the different versions
 References: No direct references to this subroutine in this source file


 This is part of the main game loop. This is where the core loop of the game
 lives, and it's in two parts. The shorter loop (just parts 5 and 6) is
 iterated when we are docked, while the entire loop from part 1 to 6 iterates
 if we are in space.

 This section covers the following:

   * Spawn a trader, i.e. a Cobra Mk III that isn't hostile, with a 50% chance
     of it having a missile, a 50% chance of it having an E.C.M., a speed
     between 16 and 31, and a gentle clockwise roll

 We call this from within the main loop, with A set to a random number.


.MTT4

 LSR A                  \ Clear bit 7 of our random number in A and set the C
                        \ flag to bit 0 of A, which is random

 STA INWK+32            \ Store this in the ship's AI flag, so this ship does
                        \ not have AI

 STA INWK+29            \ Store A in the ship's roll counter, giving it a
                        \ clockwise roll (as bit 7 is clear), and a 1 in 127
                        \ chance of it having no damping

 ROL INWK+31            \ Set bit 0 of the ship's missile count randomly (as the
                        \ C flag was set), giving the ship either no missiles or
                        \ one missile

 AND #31                \ Set the ship speed to our random number, set to a
 ORA #16                \ minimum of 16 and a maximum of 31
 STA INWK+27

 LDA #CYL               \ Add a new Cobra Mk III to the local bubble and fall
 JSR NWSHP              \ through into the main game loop again