Add hook for VBL callback

macros/GTE.Macs.s

@@ -175,9 +175,11 @@ OVERLAY_SOLID          equ   $8000      ; Overlay covers the scan line and is fu
 OVERLAY_ABOVE          equ   $0000      ; Overlay is drawn above scanline sprites
 OVERLAY_BELOW          equ   $4000      ; Overlay is drawn below scanline sprites
 
-; GetAddress table IDs
+; GetAddress IDs
 scanlineHorzOffset     equ   $0001
 scanlineHorzOffset2    equ   $0002
+tileStore              equ   $0003
+vblCallback            equ   $0004
 
 ; CopyPicToBG1 flags
 COPY_PIC_NORMAL        equ   $0000      ; Copy into BG1 buffer in "normal mode"

src/CoreImpl.s

@@ -166,8 +166,14 @@ OneSecHandler     mx        %11
 
 ; This is OK, it's referenced by a long address
 VBLTASK           hex       00000000
-                  dw        0
+TaskCnt           dw        1
                   hex       5AA5
+VblTaskCode       mx        %11
+                  lda       #1
+                  stal      TaskCnt            ; Reset the task count
+_VblTaskPatch     jml       _TaskStub          ; Just something to catch the interrupt
+_TaskStub         rtl
+                  mx        %00
 
 ; Reset the engine to a known state
 ; Blitter initialization

src/Defs.s

@@ -192,6 +192,7 @@ DIRTY_BIT_SPRITE_ARRAY equ   $0040
 scanlineHorzOffset     equ   $0001        ; Table of 416 words, a double-array of scanline offset values. Values must be in range [0, 163]
 scanlineHorzOffset2    equ   $0002        ; Table of 416 words, a double-array of scanline offset values. Values must be in range [0, 163]
 tileStore              equ   $0003
+vblCallback            equ   $0004        ; User routine to be called by VBL interrupt.  Set to $000000 to disconnect
 
 ; CopyPicToBG1 flags
 COPY_PIC_NORMAL        equ   $0000        ; Copy into BG1 buffer in "normal mode" treating the buffer as a 164x208 pixmap with stride of 256

src/Master.s

@@ -2,7 +2,7 @@
 
             TYP   $BA                  ; Tool set file
             DSK   Tool160
-            XPL
+             XPL
 
 ; Main toolbox interface and code
 
@@ -12,41 +12,41 @@
 ; 64KB Tile Memory
 
             ASM   static/TileData.s
-            KND   #$1001               ; Type and Attributes ($10=Static,$01=Data)
+            KND   #$1101               ; Type and Attributes ($10=Static,$01=Data)
             ALI   BANK
             SNA   TDATA
 
 ; 64KB Sprite Plane Data
 
             ASM   static/SprData.s
-            KND   #$1001               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
+            KND   #$1101               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
             ALI   BANK
             SNA   SDATA
 
 ; 64KB Sprite Mask Data
 
             ASM   static/SprMask.s
-            KND   #$1001               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
+            KND   #$1101               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
             ALI   BANK
             SNA   SMASK
 
 ; 64KB Tile Store
 
             ASM   static/TileStore.s
-            KND   #$1001               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
+            KND   #$1101               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
             ALI   BANK
             SNA   TSTORE
 
 ; 64KB Rotation Data Tables
 
             ASM   RotData.s
-            KND   #$1001               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
+            KND   #$1101               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
             ALI   BANK
             SNA   ROTDATA
 
 ; Additional code
 
 ;            ASM   FastCopies.s
-;            KND   #$1001               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
+;            KND   #$1101               ; Type and Attributes ($11=Static+Bank Relative,$01=Data)
 ;            ALI   BANK
 ;            SNA   FASTCPY

src/Tiles.s

@@ -6,7 +6,7 @@
 ; X = first tile
 ; Y = last tile
 ;
-; To copy in three tiles starting at tile 5, for example, X = 5 and Y = 9
+; To copy in four tiles starting at tile 5, for example, X = 5 and Y = 9
 _LoadTileSet
                 txa
                 _Mul128                   ; Jump to the target location

src/Tool.s

@@ -887,7 +887,7 @@ _TSSetBG1Scale
                 sta     BG1Scaling
                 _TSExit #0;#2
 
-; Pointer GetAddress(tblId)
+; Pointer GetAddress(addrId)
 _TSGetAddress
 :tblId          equ     FirstParam+0
 :output         equ     FirstParam+2
@@ -919,7 +919,7 @@ _TSGetAddress
 :out
                 _TSExit #0;#2
 
-; SetAddress(tblId, Pointer)
+; SetAddress(addrId, Pointer)
 _TSSetAddress
 :ptr            equ     FirstParam+0
 :tblId          equ     FirstParam+4
@@ -944,7 +944,27 @@ _TSSetAddress
                 lda     :ptr+2,s
                 sta     BG1StartXMod164Tbl+2
                 bra     :out
-:next_2
+
+:next_2         cmp     #vblCallback
+                bne     :next_3
+
+                lda     :ptr,s
+                ora     :ptr+2,s
+                beq     :vbl_restore
+
+                lda     :ptr,s
+                stal    _VblTaskPatch+1         ; long addressing because we're patching code in the K bank
+                lda     :ptr+1,s
+                stal    _VblTaskPatch+2
+                bra     :out
+
+:vbl_restore
+                lda     #_TaskStub
+                stal    _VblTaskPatch+1
+                lda     #>_TaskStub
+                stal    _VblTaskPatch+2
+                bra     :out
+:next_3
 :out
                 _TSExit #0;#6
 

src/render/Render.s

@@ -4,7 +4,7 @@ _RenderTile
             lda   TileStore+TS_SPRITE_FLAG,x       ; any sprites on this tile?
             bne   _HasSprites
 
-; Probably best to rework this to just jump to the tile routine directly, event if there
+; Probably best to rework this to just jump to the tile routine directly, even if there
 ; is some boilerplate code because it is useful to be able to access the data bank before
 ; switching to the code field bank.