mirror of
https://github.com/lscharen/iigs-game-engine.git
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92 lines
4.0 KiB
ArmAsm
92 lines
4.0 KiB
ArmAsm
; _TBDynamicPrioritySpriteTile
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;
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; Variant of _TBDynamicSpriteTile (Tile10001), but draw the sprite data behind the dynamic tile
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_TBDynamicPrioritySpriteTile_00
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jsr _TBDynamicPriorityDataAndMask
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jmp _TBFillJMPOpcode
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_TBDynamicPriorityDataAndMask
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sty _Y_REG ; This is restored in the macro
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sta _X_REG ; Cache some column values derived from _X_REG
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tax
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clc
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ldal JTableOffset,x ; Get the address offset and add to the base address
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adc _BASE_ADDR ; of the current code field line
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sta _JTBL_CACHE
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lda _TILE_ID ; Get the original tile descriptor
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and #$007F ; clamp to < (32 * 4)
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ora #$3580 ; Pre-calc the AND $80,x opcode + operand
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xba
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sta _OP_CACHE ; This is an op to load the dynamic tile data
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ldx _SPR_X_REG
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CopyDynPriSpriteWord {0*SPRITE_PLANE_SPAN};$0003
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CopyDynPriSpriteWord {1*SPRITE_PLANE_SPAN};$1003
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CopyDynPriSpriteWord {2*SPRITE_PLANE_SPAN};$2003
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CopyDynPriSpriteWord {3*SPRITE_PLANE_SPAN};$3003
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CopyDynPriSpriteWord {4*SPRITE_PLANE_SPAN};$4003
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CopyDynPriSpriteWord {5*SPRITE_PLANE_SPAN};$5003
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CopyDynPriSpriteWord {6*SPRITE_PLANE_SPAN};$6003
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CopyDynPriSpriteWord {7*SPRITE_PLANE_SPAN};$7003
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ldx _X_REG
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clc
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ldal JTableOffset+2,x ; Get the address offset and add to the base address
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adc _BASE_ADDR ; of the current code field line
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sta _JTBL_CACHE
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lda _OP_CACHE
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adc #$0200
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sta _OP_CACHE
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ldx _SPR_X_REG
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CopyDynPriSpriteWord {0*SPRITE_PLANE_SPAN}+2;$0000
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CopyDynPriSpriteWord {1*SPRITE_PLANE_SPAN}+2;$1000
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CopyDynPriSpriteWord {2*SPRITE_PLANE_SPAN}+2;$2000
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CopyDynPriSpriteWord {3*SPRITE_PLANE_SPAN}+2;$3000
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CopyDynPriSpriteWord {4*SPRITE_PLANE_SPAN}+2;$4000
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CopyDynPriSpriteWord {5*SPRITE_PLANE_SPAN}+2;$5000
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CopyDynPriSpriteWord {6*SPRITE_PLANE_SPAN}+2;$6000
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CopyDynPriSpriteWord {7*SPRITE_PLANE_SPAN}+2;$7000
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rts
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; Masked renderer for a dynamic tile with sprite data overlaid.
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;
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; ]1 : sprite plane offset
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; ]2 : code field offset
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CopyDynPriSpriteWord MAC
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; Need to fill in the first 9 bytes of the JMP handler with the following code sequence where
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; the data and mask from from the sprite plane
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;
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; lda #DATA
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; and $80,x
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; ora $00,x
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; bra *+16
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lda _JTBL_CACHE ; Get the offset to the exception handler for this column
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ora #{]2&$F000} ; adjust for the current row offset
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sta: ]2+1,y
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tay ; This becomes the new address that we use to patch in
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lda #$00A9 ; LDA #DATA
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sta: $0000,y
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ldal spritedata+{]1},x
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sta: $0001,y
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lda _OP_CACHE
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sta: $0003,y ; AND $80,x
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eor #$8020 ; Switch the opcode to an ORA and remove the high bit of the operand
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sta: $0005,y ; ORA $00,x
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lda #$0E80 ; branch to the prologue (BRA *+16)
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sta: $0007,y
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ldy _Y_REG ; restore original y-register value and move on
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eom |