67 lines
2.6 KiB
ArmAsm
67 lines
2.6 KiB
ArmAsm
; _TBSolidTile
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;
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; Define the addresses of the subroutines that draw the normal and flipped variants of the tiles, both
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; in the optimized (no second background) and normal cases.
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;
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; On entry, the following register values need to be set
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;
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; X : address of base tile in the tiledata bank (tileId * 128)
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; Y : address of the top-left corder of the tile location in the code field
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; B : set to the code field bank
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_TBSolidTile_00
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jsr _TBCopyData
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jmp _TBFillPEAOpcode
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_TBSolidTile_0H
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jsr _TBCopyData
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jmp _TBFillPEAOpcode
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_TBSolidTile_V0
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jsr _TBCopyDataV
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jmp _TBFillPEAOpcode
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_TBSolidTile_VH
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jsr _TBCopyDataV
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jmp _TBFillPEAOpcode
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; The workhorse blitter. This blitter copies tile data into the code field without masking. This is the
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; most common blitter function. It is slightly optimized to fall through to the code that sets the PEA
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; opcodes in order to be slightly more efficient given it's frequent usage.
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;
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; There is a small variation of this blitter that just copies the data without setting the PEA opcodes. This
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; is used by the engine when the capabilitiy bits have turned off the second background layer. In fact, most
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; of the tile rendering routines have an optimized version for this important use case. Skipping the opcode
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; step results in a 37% speed boost in tile rendering.
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;
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; This does not increase the FPS by 37% because only a small number of tiles are drawn each frame, but it
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; has an impact and can significantly help out when sprites trigger more dirty tile updates than normal.
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_TBCopyDataFast
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tax
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_TBCopyData
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]line equ 0
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lup 8
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ldal tiledata+{]line*4},x
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sta: $0004+{]line*$1000},y
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ldal tiledata+{]line*4}+2,x
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sta: $0001+{]line*$1000},y
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]line equ ]line+1
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--^
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rts
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_TBCopyDataVFast
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tax
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_TBCopyDataV
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]src equ 7
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]dest equ 0
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lup 8
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ldal tiledata+{]src*4},x
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sta: $0004+{]dest*$1000},y
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ldal tiledata+{]src*4}+2,x
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sta: $0001+{]dest*$1000},y
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]src equ ]src-1
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]dest equ ]dest+1
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--^
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rts
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