mirror of
https://github.com/lscharen/iigs-game-engine.git
synced 2025-03-10 17:33:24 +00:00
Add initial build-out of BG1 tile map support
This commit is contained in:
Lucas Scharenbroich
parent
4c5b090afe
commit
e607612344
@ -145,7 +145,7 @@ mixed cmp #$FFFF ; All 1's in the mask is fully transparent
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ldx _X_REG ; Get the addressing offset
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ldal JTableOffset,x ; Get the address offset and add to the base address
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clc ; may be able to be removed...
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; clc ; may be able to be removed...
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adc _BASE_ADDR ; of the current code field line
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adc #{]3&$F000} ; adjust for the current row offset
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sta: ]3+1,y
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@ -175,3 +175,6 @@ transparent
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next
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eom
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@ -3,9 +3,9 @@ MoveLeft
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adc StartX ; Increment the virtual X-position
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jsr SetBG0XPos
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; lda StartX
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; lsr
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; jsr SetBG1XPos
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lda StartX
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lsr
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jsr SetBG1XPos
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jsr Render
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rts
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@ -19,9 +19,9 @@ MoveRight
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lda #0
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jsr SetBG0XPos
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; lda StartX
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; lsr
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; jsr SetBG1XPos
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lda StartX
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lsr
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jsr SetBG1XPos
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jsr Render
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pla
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@ -294,3 +294,4 @@ _DoTimers
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@ -128,13 +128,7 @@ NO_MUSIC equ 1 ; turn music + tool load
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; Set up our level data
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jsr BG0SetUp
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ldx #0
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ldy #0
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lda #56
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jsr CopyTile
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; jsr Render
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jsr WaitForKey
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jsr BG1SetUp
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; Allocate room to load data
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@ -142,13 +136,17 @@ NO_MUSIC equ 1 ; turn music + tool load
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sta BankLoad ; Store "Bank Pointer"
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jsr MovePlayerToOrigin ; Put the player at the beginning of the map
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lda #74
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jsr SetBG0XPos
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lda #DIRTY_BIT_BG0_REFRESH ; Redraw all of the tiles on the next Render
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ora #DIRTY_BIT_BG1_REFRESH
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tsb DirtyBits
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; jsr DoTiles
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; jsr DoLoadBG1
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; jsr Demo
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jsr Render
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EvtLoop
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jsr ReadControl
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and #$007F ; Ignore the buttons for now
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@ -273,6 +271,8 @@ Fatal brk $00
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MovePlayerToOrigin
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lda #0 ; Set the player's position
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jsr SetBG0XPos
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lda #0
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jsr SetBG1XPos
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lda TileMapHeight
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asl
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@ -280,7 +280,10 @@ MovePlayerToOrigin
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asl
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sec
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sbc ScreenHeight
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pha
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jsr SetBG0YPos
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pla
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jsr SetBG1YPos
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rts
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@ -397,10 +400,6 @@ DoTiles
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lda :tile,s
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jsr CopyTile
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; lda :tile,s
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; eor #$0003
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; sta :tile,s
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lda :column,s
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inc
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sta :column,s
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@ -1298,3 +1297,13 @@ qtRec adrl $0000
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PUT TileMap.s
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PUT App.TileMapBG0.s
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PUT App.TileMapBG1.s
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17
src/Render.s
17
src/Render.s
@ -65,17 +65,18 @@ Render
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; used in all of the other loops
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jsr _ApplyBG0YPos ; Set stack addresses for the virtual lines to the physical screen
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jsr _ApplyBG1YPos
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; _ApplyBG0Xpos need to be split because we have to set the offsets, then draw in any updated tiles, and
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; finally patch out the code field. Right now, the BRA operand is getting overwritten by tile data.
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jsr _ApplyBG0XPosPre
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jsr _ApplyBG1XPosPre
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jsr _UpdateBG0TileMap
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; jsr _UpdateBG1TileMap
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jsr _ApplyBG0XPos ; Patch the PEA instructions with exit BRA opcode
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; jsr _ApplyBG1YPos ; Adjust the index values into the BG1 bank buffer
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; jsr _ApplyBG1XPos ; Adjust the direct page pointers to the BG1 bank
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jsr _ApplyBG1XPos ; Patch the PEA instructions with exit BRA opcode
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; Copy any tiles that have come into view
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@ -112,6 +113,11 @@ Render
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lda StartX
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sta OldStartX
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lda BG1StartY
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sta OldBG1StartY
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lda BG1StartX
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sta OldBG1StartX
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stz DirtyBits
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rts
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@ -129,5 +135,10 @@ Render
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277
src/TileMap.s
277
src/TileMap.s
@ -230,7 +230,6 @@ _UpdateBG0TileMap
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; This is a private subroutine that draws in tiles into the code fields using the
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; data from the tilemap and the local :Top, :Left, :Bottom and :Right parameters.
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:DrawRectBG0
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lda :Bottom
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sec
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sbc :Top
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@ -383,3 +382,279 @@ _UpdateBG0TileMap
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bne :loop
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rts
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; Exact same logic as _UpdateBG0TileMap, except for the other background
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_UpdateBG1TileMap
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:Left equ tmp0
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:Right equ tmp1
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:Top equ tmp2
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:Bottom equ tmp3
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lda BG1StartY ; calculate the tile index of the current location
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lsr
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lsr
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lsr
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sta BG1TileOriginY
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lda OldBG1StartY
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lsr
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lsr
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lsr
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sta OldBG1TileOriginY
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lda BG1StartX
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lsr
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lsr
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sta BG1TileOriginX
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lda OldBG1StartX
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lsr
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lsr
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sta OldBG1TileOriginX
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; Figure out the two rectangular regions that need to be updated.
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stz :Left ; prepare to do the entire screen
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lda ScreenTileWidth ; and then whack off the parts
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sta :Right ; that are not needed
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stz :Top ; since the ranges are inclusive, we are
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lda ScreenTileHeight ; always going to be drawing width+1 tiles
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sta :Bottom ; which takes care of edge tiles.
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; If we are supposed to refresh the whole field, just do that and return
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lda #DIRTY_BIT_BG1_REFRESH
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bit DirtyBits
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beq :NoRefresh
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trb DirtyBits ; Clear the dirty bit
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:FullScreen jmp _DrawRectBG1 ; Let the DrawRectBG1 RTS take care of the return for us
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:NoRefresh
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lda BG1TileOriginY
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cmp OldBG1TileOriginY
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beq :NoYUpdate ; if equal, don't change Y
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sec
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sbc OldBG1TileOriginY ; find the difference; D = Y_new - Y_old
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bpl :DoBottom ; if we scrolled up, fill in the bottom row(s)
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eor #$FFFF ; if we scrolled down, Y_new < Y_old and we need
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cmp :Bottom ; to fill in the top row(s) from 0 to Y_new - Y_old - 1
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bcs :FullScreen ; If the displacement was very large, just fill in the whole screen
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sta :Bottom
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bra :DoYUpdate
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:DoBottom
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eor #$FFFF ; same explanation as above, except we are filling in from
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inc ; Bottom - (Y_new - Y_old) to Bottom
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clc
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adc ScreenTileHeight
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bmi :FullScreen
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sta :Top
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:DoYUpdate
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jsr _DrawRectBG1 ; Fill in the rectangle.
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; We performed an update in the Y-direction, so now change the bounds so
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; an update in the X-direction will not draw too many rows
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lda :Top
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beq :drewTop
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dec ; already did Y to HEIGHT, so only need to draw from
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sta :Bottom ; 0 to (Y-1) for any horizontal updates
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stz :Top
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bra :NoYUpdate
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:drewTop
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lda :Bottom ; opposite, did 0 to Y
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inc ; so do Y+1 to HEIGHT
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sta :Top
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lda ScreenTileHeight
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sta :Bottom
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; The Top and Bottom are set the the correct values to draw in whatever potential range of tiles
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; need to be draws if there was any horizontal displacement
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:NoYUpdate
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lda BG1TileOriginX ; Did the first column of the tile map change from before?
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cmp OldBG1TileOriginX ; Did it change from before?
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beq :NoXUpdate ; no, so we can ignore this
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sec
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sbc OldBG1TileOriginX ; find the difference
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bpl :DoRightSide ; did we move in a pos or neg?
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; Handle the two sides in an analagous way as the vertical code
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eor #$FFFF
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cmp :Right
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bcs :FullScreen
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sta :Right
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bra :DoXUpdate
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:DoRightSide
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eor #$FFFF
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inc
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clc
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adc ScreenTileWidth
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bmi :FullScreen
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sta :Left
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:DoXUpdate
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jsr _DrawRectBG1 ; Fill in the rectangle.
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:NoXUpdate
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rts
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; This is a private subroutine that draws in tiles into the code fields using the
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; data from the tilemap and the local :Top, :Left, :Bottom and :Right parameters.
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_DrawRectBG1
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:Left equ tmp0
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:Right equ tmp1
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:Top equ tmp2
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:Bottom equ tmp3
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:Width equ tmp4
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:Height equ tmp5
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:MulA equ tmp6 ; Scratch space for multiplication
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:MulB equ tmp7
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:Offset equ tmp8 ; Address offset into the tilemap
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:Span equ tmp9
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:GlobalTileIdxX equ tmp10
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:GlobalTileIdxY equ tmp11
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:BlkX equ tmp12
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:BlkY equ tmp13
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lda :Bottom
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sec
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sbc :Top
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inc
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sta :Height ; Maximum value of 26 (top = 0, bottom = 25)
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lda :Right
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sec
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sbc :Left
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inc
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sta :Width ; Maximum value of 41 (left = 0, right = 40)
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; Compute the offset into the tile array of the top-left corner
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lda :Left
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clc
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adc BG1TileOriginX
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sta :GlobalTileIdxX
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lda :Top
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clc
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adc BG1TileOriginY ; This is the global verical index
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sta :GlobalTileIdxY
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ldx BG1TileMapWidth
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jsr :MulAX
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clc
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adc :GlobalTileIdxX
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asl ; Double for word sizes
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sta :Offset ; Stash the pointer offset in Y
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; Draw the tiles
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lda BG1TileMapWidth
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sec
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sbc :Width
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asl ; This is the number of bytes to move the Offset to advance from the end of
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sta :Span ; one line to the beginning of the next
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; Now we need to figure out the code field tile coordinate of corner of
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; play field. That is, becuase the screen is scrolling, the location of
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; tile (0, 0) could be anywhere within the code field
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lda BG1StartYMod208 ; This is the code field line that is at the top of the screen
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and #$FFF8 ; Clamp to the nearest block
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lsr
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lsr
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lsr ; Could optimize because the Tile code shifts back....
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clc
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adc :Top
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cmp #MAX_TILE_Y+1 ; Top can be less than or equal to 25
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bcc *+5
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sbc #MAX_TILE_Y+1
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sta :BlkY ; This is the Y-block we start drawing from
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lda BG1StartXMod164 ; Do the same thing for X, except only need to clamp by 4
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and #$FFFC
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lsr
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lsr
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clc
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adc :Left
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cmp #MAX_TILE_X+1 ; Left can be less than or equal to 40
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bcc *+5
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sbc #MAX_TILE_X+1
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sta :BlkX
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; Call the copy tile routine to blit the tile data into the playfield
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;
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; A = Tile ID (0 - 1023)
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; X = Tile column (0 - 40)
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; Y = Tile row (0 - 25)
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pei :BlkX ; cache the starting X-block index to restore later
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pei :Width ; cache the Width value to restore later
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:yloop
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:xloop
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ldy :Offset ; Set up the arguments and call the tile blitter
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lda [BG1TileMapPtr],y
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iny ; pre-increment the address. A bit faster than two "INC DP" instructions
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iny
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sty :Offset
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ldx :BlkX
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ldy :BlkY
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jsr CopyTileBG1
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lda :BlkX
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inc
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cmp #MAX_TILE_X+1 ; If we go past the maximum block index, wrap around
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bcc *+5
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lda #0
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sta :BlkX
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dec :Width ; Decrement out count
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bne :xloop
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lda :Offset ; Move to the next line of the Tile Map
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clc
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adc :Span
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sta :Offset
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lda 3,s ; Reset the BlkX
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sta :BlkX
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lda 1,s ; Reset the width
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sta :Width
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lda :BlkY ; The y lookup has a double-length array, may not need the bounds check
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inc
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cmp #MAX_TILE_Y+1
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bcc *+5
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lda #0
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sta :BlkY
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dec :Height ; Have we done all of the rows?
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bne :yloop
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pla ; Pop off cached values
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pla
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rts
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@ -40,14 +40,16 @@ SetBG1YPos
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; these are all direct page values
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;
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; Note: This routine can be optimized as an unrolled loop of PEI instructions
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_ApplyBG1XPos
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lda BG1StartX
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_ApplyBG1XPosPre
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lda BG1StartX ; This is the starting byte offset (0 - 163)
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jsr Mod164
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sta BG1StartXMod164
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rts
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_ApplyBG1XPos
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lda #162
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sec
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sbc StartXMod164
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sbc StartXMod164 ; Need to compensate for both BG0 and BG1 positions
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bpl *+6
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clc
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adc #164
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@ -609,3 +611,7 @@ ApplyBG1OffsetValues
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:none rts
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BG1YCache ds 32
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@ -54,11 +54,11 @@ _BltRange
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; Now we need to set up the Bank, Stack Pointer and Direct Page registers for calling into
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; the code field
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lda StartX
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bit #$01
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beq :primary
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lda BG1AltBank
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bra :alt
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; lda StartX
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; bit #$01
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; beq :primary
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; lda BG1AltBank
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; bra :alt
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:primary lda BG1DataBank
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:alt
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pha
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@ -95,3 +95,4 @@ stk_save lda #0000 ; load the stack
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; we don't do anything sprite related; just call function pointers provided to us.
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_RenderSprites
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rts
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@ -27,7 +27,7 @@ Col2CodeOffset lup 82
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dw CODE_TOP+{{81-]step}*PER_TILE_SIZE}
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]step equ ]step+1
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--^
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; dw CODE_TOP
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dw CODE_TOP+{81*PER_TILE_SIZE}
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; A parallel table to Col2CodeOffset that holds the offset to the exception handler address for each column
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SNIPPET_SIZE equ 32
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@ -37,6 +37,7 @@ JTableOffset lup 82
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dw SNIPPET_BASE+{{81-]step}*SNIPPET_SIZE}
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]step equ ]step+1
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--^
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dw SNIPPET_BASE+{81*SNIPPET_SIZE}
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; Table of BRA instructions that are used to exit the code field. Separate tables for
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; even and odd aligned cases.
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@ -252,3 +253,6 @@ BG1YTable lup 208
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BG1YOffsetTable lup 26
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dw 1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0
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--^
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