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⌂ ∞ ▽ Elite on the 6502

Version analysis of DENGY

This code appears in the following versions (click to see it in the source code):

Code variations between these versions are shown below.

       Name: DENGY
       Type: Subroutine
   Category: Flight
    Summary: Drain some energy from the energy banks



 Returns:

   Z flag               Set if we have no energy left, clear otherwise



.DENGY

 DEC ENERGY             \ Decrement the energy banks in ENERGY

 PHP                    \ Save the flags on the stack

Code variation 1 of 1Specific to an individual platform

Tap on a block to expand it, and tap it again to revert.

Cassette, Flight, Docked, 6502SP, Electron
Master
 BNE P%+5               \ If the energy levels are not yet zero, skip the
                        \ following instruction

 INC ENERGY             \ The minimum allowed energy level is 1, and we just
                        \ reached 0, so increment ENERGY back to 1

 BNE paen2              \ If the energy levels are not yet zero, skip the
                        \ following instruction

 INC ENERGY             \ The minimum allowed energy level is 1, and we just
                        \ reached 0, so increment ENERGY back to 1

.paen2

 PLP                    \ Restore the flags from the stack, so we return with
                        \ the Z flag from the DEC instruction above

 RTS                    \ Return from the subroutine