226 lines
7.7 KiB
ArmAsm
226 lines
7.7 KiB
ArmAsm
; Old code the was in Version 1, but is not needed. May be adapted for Verions 2.
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; Y = _Sprites array offset
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_EraseSpriteY
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lda _Sprites+OLD_VBUFF_ADDR,y
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beq :noerase
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ldx _Sprites+SPRITE_DISP,y ; get the dispatch index for this sprite (32 values)
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jmp (:do_erase,x)
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:noerase rts
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:do_erase dw _EraseTileSprite8x8,_EraseTileSprite8x8,_EraseTileSprite8x8,_EraseTileSprite8x8
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dw _EraseTileSprite8x16,_EraseTileSprite8x16,_EraseTileSprite8x16,_EraseTileSprite8x16
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dw _EraseTileSprite16x8,_EraseTileSprite16x8,_EraseTileSprite16x8,_EraseTileSprite16x8
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dw _EraseTileSprite16x16,_EraseTileSprite16x16,_EraseTileSprite16x16,_EraseTileSprite16x16
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dw _EraseTileSprite8x8,_EraseTileSprite8x8,_EraseTileSprite8x8,_EraseTileSprite8x8
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dw _EraseTileSprite8x16,_EraseTileSprite8x16,_EraseTileSprite8x16,_EraseTileSprite8x16
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dw _EraseTileSprite16x8,_EraseTileSprite16x8,_EraseTileSprite16x8,_EraseTileSprite16x8
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dw _EraseTileSprite16x16,_EraseTileSprite16x16,_EraseTileSprite16x16,_EraseTileSprite16x16
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; A = bank address
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_EraseTileSprite8x8
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tax
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phb ; Save the bank to switch to the sprite plane
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pei SpriteBanks
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plb ; pop the data bank (low byte)
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]line equ 0
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lup 8
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stz: {]line*SPRITE_PLANE_SPAN}+0,x
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stz: {]line*SPRITE_PLANE_SPAN}+2,x
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]line equ ]line+1
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--^
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plb ; pop the mask bank (high byte)
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lda #$FFFF
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]line equ 0
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lup 8
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sta: {]line*SPRITE_PLANE_SPAN}+0,x
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sta: {]line*SPRITE_PLANE_SPAN}+2,x
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]line equ ]line+1
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--^
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plb
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rts
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_EraseTileSprite8x16
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tax
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phb ; Save the bank to switch to the sprite plane
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pei SpriteBanks
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plb ; pop the data bank (low byte)
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]line equ 0
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lup 16
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stz: {]line*SPRITE_PLANE_SPAN}+0,x
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stz: {]line*SPRITE_PLANE_SPAN}+2,x
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]line equ ]line+1
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--^
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plb ; pop the mask bank (high byte)
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lda #$FFFF
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]line equ 0
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lup 16
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sta: {]line*SPRITE_PLANE_SPAN}+0,x
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sta: {]line*SPRITE_PLANE_SPAN}+2,x
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]line equ ]line+1
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--^
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plb
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rts
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_EraseTileSprite16x8
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tax
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phb ; Save the bank to switch to the sprite plane
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pei SpriteBanks
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plb ; pop the data bank (low byte)
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]line equ 0
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lup 8
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stz: {]line*SPRITE_PLANE_SPAN}+0,x
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stz: {]line*SPRITE_PLANE_SPAN}+2,x
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stz: {]line*SPRITE_PLANE_SPAN}+4,x
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stz: {]line*SPRITE_PLANE_SPAN}+6,x
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]line equ ]line+1
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--^
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plb ; pop the mask bank (high byte)
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lda #$FFFF
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]line equ 0
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lup 8
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sta: {]line*SPRITE_PLANE_SPAN}+0,x
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sta: {]line*SPRITE_PLANE_SPAN}+2,x
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sta: {]line*SPRITE_PLANE_SPAN}+4,x
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sta: {]line*SPRITE_PLANE_SPAN}+6,x
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]line equ ]line+1
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--^
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plb
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rts
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_EraseTileSprite16x16
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tax
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phb ; Save the bank to switch to the sprite plane
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pei SpriteBanks
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plb ; pop the data bank (low byte)
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]line equ 0
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lup 16
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stz: {]line*SPRITE_PLANE_SPAN}+0,x
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stz: {]line*SPRITE_PLANE_SPAN}+2,x
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stz: {]line*SPRITE_PLANE_SPAN}+4,x
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stz: {]line*SPRITE_PLANE_SPAN}+6,x
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]line equ ]line+1
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--^
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plb ; pop the mask bank (high byte)
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lda #$FFFF
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]line equ 0
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lup 16
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sta: {]line*SPRITE_PLANE_SPAN}+0,x
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sta: {]line*SPRITE_PLANE_SPAN}+2,x
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sta: {]line*SPRITE_PLANE_SPAN}+4,x
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sta: {]line*SPRITE_PLANE_SPAN}+6,x
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]line equ ]line+1
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--^
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plb
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rts
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; First, if there is only one sprite, then we can skip any overhead and do a single lda/and/ora/sta to put the
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; sprite data on the screen.
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;
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; Second, if there are 4 or less, then we "stack" the sprite data using an unrolled loop that allows each
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; sprite to just be a single and/ora pair and the final result is not written to any intermediate memory buffer.
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;
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; Third, if there are 5 or more sprites, then we assume that the sprites are "dense" and that there will be a
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; non-trivial amount of overdraw. In this case we do a series of optimized copies of the sprite data *and*
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; masks into a direct page buffer in *reverse order*. Once a mask value becomes zero, then nothing else can
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; show through and that value can be skipped. Once all of the mask values are zero, then the render is terminated
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; and the data buffer copied to the final destination.
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;
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; Note that these rendering algorithms impose a priority ordering on the sprites where lower sprite IDs are drawn
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; underneath higher sprite IDs.
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RenderActiveSpriteTiles
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cmp #0 ; Is there only one active sprite? If so optimise
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bne :many
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ldx vbuff ; load the address to the (adjusted) sprite tile
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lda TileStore+TS_SCREEN_ADDR,y
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tay
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lda tiledata+0,y
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andl spritemask,x
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oral spritedata,x
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sta 00,s
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lda tiledata+2,y
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andl spritemask+2,x
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oral spritedata+2,x
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sta 02,s
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...
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tsc
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adc #320
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tcs
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...
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lda tiledata+{line*4},y
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andl spritemask+{line*SPAN},x
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oral spritedata+{line*SPAN},x
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sta 160,s
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lda tiledata+{line*4}+2,y
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andl spritemask+{line*SPAN}+2,x
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oral spritedata+{line*SPAN}+2,x
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sta 162,s
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rts
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:many
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lda TileStore+TS_SCREEN_ADDR,y
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tcs
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lda TileStore+TS_TILE_ADDR,y
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tay
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ldx count
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jmp (:arr,x)
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lda tiledata+0,y
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ldx vbuff
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andl spritemask,x
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oral spritedata,x
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ldx vbuff+2
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andl spritemask,x
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oral spritedata,x
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ldx vbuff+4
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andl spritemask,x
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oral spritedata,x
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...
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sta 00,s
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ldx count
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jmp (:arr,x)
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lda tiledata+0,y
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ldx vbuff
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andl spritemask,x
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oral spritedata,x
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ldx vbuff+2
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andl spritemask,x
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oral spritedata,x
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ldx vbuff+4
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andl spritemask,x
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oral spritedata,x
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...
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sta 02,s
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sta 160,s
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sta 162,s
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tsc
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adc #320 |