Drawing the screen: flagsForClearing

       Name: flagsForClearing                                        [Show more]
       Type: Variable
   Category: Drawing the screen
    Summary: A bitplane mask to control how bitplane buffer clearing works in
             the ClearPlaneBuffers routine
    Context: See this variable in context in the source code
 References: This variable is used as follows:
             * ClearPlaneBuffers (Part 1 of 2) uses flagsForClearing


.flagsForClearing

 EQUB %00110000         ; The bitplane flags with ones in this byte must be
                        ; clear for the clearing process in ClearPlaneBuffers
                        ; to be activated
                        ;
                        ; So this configuration means that clearing will only be
                        ; attempted on bitplanes where:
                        ;
                        ;   * We are in the process of sending this bitplane's
                        ;     data to the PPU (bit 4 is set)
                        ;
                        ;   * We have already sent all the data to the PPU for
                        ;     this bitplane (bit 5 is set)
                        ;
                        ; If both bitplane flags are clear, then the buffers are
                        ; not cleared
                        ;
                        ; Note that this is separate from bit 3, which controls
                        ; whether clearing is enabled and which overrides the
                        ; above (bit 2 must be set for any clearing to take
                        ; place)