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⌂ ∞ Aviator on the BBC Micro

Graphics: FillCanopy

       Name: FillCanopy                                              [Show more]
       Type: Subroutine
   Category: Graphics
    Summary: Fill the canopy with a specified colour, leaving the canopy edges
             alone

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * Crash calls FillCanopy




 Arguments:

   X                    The colour to fill the canopy with



.FillCanopy

 TXA                    \ Copy the colour into X

 LDX #19                \ Set R = 19, so we clear 19 character rows (the whole
 STX R                  \ canopy view except for the top row containing the
                        \ canopy edge)

 LDY #HI(row1_char1_0)  \ Set (Y X) to the screen address for row 1, character
 LDX #LO(row1_char1_0)  \ block 1

                        \ Fall through into FillCanopyRows to fill the canopy
                        \ view, from the top row to the bottom, avoiding the top
                        \ and side edges