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38 lines
1.5 KiB
ArmAsm
38 lines
1.5 KiB
ArmAsm
; Direct page locations used by the engine
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ScreenHeight equ 0 ; Height of the playfield in scan lines
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ScreenWidth equ 2 ; Width of the playfield in bytes
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ScreenY0 equ 4 ; First vertical line on the physical screen of the playfield
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ScreenY1 equ 6 ; End of playfield on the physical screen. If the height is 20 and Y0 is
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ScreenX0 equ 8 ; 100, then ScreenY1 = 120.
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ScreenX1 equ 10
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ScreenTileHeight equ 12 ; Height of the playfield in 8x8 blocks
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ScreenTileWidth equ 14 ; Width of the playfield in 8x8 blocks
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StartY equ 16 ; Which code buffer line displays first on screen. Range = 0 to 207
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EngineMode equ 18 ; Defined the mode/capabilities that are enabled
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; bit 0: 0 = Single Background, 1 = Parallax
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DirtyBits equ 20 ; Identify values that have changed between frames
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BG1DataBank equ 22 ; Data bank that holds BG1 layer data
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BlitterDP equ 23 ; Direct page address the holder blitter data
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bstk equ 224 ; 16-byte stack to push bank addresses
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tmp0 equ 240 ; 16 bytes of temporary space to be used as scratch
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tmp1 equ 242
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tmp2 equ 244
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tmp3 equ 246
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tmp4 equ 248
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tmp5 equ 250
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tmp6 equ 252
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tmp7 equ 254
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DIRTY_BIT_BG0_X equ $0001
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DIRTY_BIT_BG0_Y equ $0002
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