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BBC Micro Elite

Dashboard: PZW (6502SP version)

Name: PZW [View in context] Type: Subroutine Category: Dashboard Summary: Fetch the current dashboard colours, to support flashing
Set A and X to the colours we should use for indicators showing dangerous and safe values respectively. This enables us to implement flashing indicators, which is one of the game's configurable options. If flashing is enabled, the colour returned in A (dangerous values) will be red for 8 iterations of the main loop, and green for the next 8, before going back to red. If we always use PZW to decide which colours we should use when updating indicators, flashing colours will be automatically taken care of for us. The values returned are #GREEN2 for green and #RED2 for red. These are mode 2 bytes that contain 2 pixels, with the colour of each pixel given in four bits. Returns: A The colour to use for indicators with dangerous values X The colour to use for indicators with safe values
.PZW LDX #STRIPE \ Set X to the dashboard stripe colour, which is stripe \ 5-1 (magenta/red) LDA MCNT \ A will be non-zero for 8 out of every 16 main loop AND #%00001000 \ counts, when bit 4 is set, so this is what we use to \ flash the "danger" colour AND FLH \ A will be zeroed if flashing colours are disabled BEQ P%+5 \ If A is zero, skip the next two instructions LDA #GREEN2 \ Otherwise flashing colours are enabled and it's the RTS \ main loop iteration where we flash them, so set A to \ dashboard colour 2 (green) and return from the \ subroutine LDA #RED2 \ Set A to dashboard colour 1 (red) RTS \ Return from the subroutine