VBL test compatible with IIe and IIc

src/inc/dgrlib.plh

@@ -6,6 +6,7 @@ import dgrlib
     predef dgrTile(x, y, src)#0
     predef dgrTileStr(x, y, tilestr, strlen, tilebuff)#0
     predef dgrFill(x, y, tile)#0
+    predef dgrVLB#0
     predef dgrClear(clr)#0
     predef dgrMode(mode)#1
     predef dgrShow(page)#1

src/inc/grlib.plh

@@ -6,6 +6,7 @@ import grlib
     predef grTile(x, y, src)#0
     predef grTileStr(x, y, tilestr, strlen, tilebuff)#0
     predef grFill(x, y, tile)#0
+    predef dgrVLB#0
     predef grClear(clr)#0
     predef grMode(mode)#1
     predef grShow(page)#1

src/libsrc/apple/dgrlib.pla

@@ -492,39 +492,23 @@ asm _dgrFillTile
         RTS
 end
 //
-// Wait for VLB - Only IIe/IIGS.
+// Wait for VLB
 //
-asm vlbWait#0
+export asm dgrVLB#0
+        PHP
+        SEI
+        STA     $C079   ; Enable IOU access and reset VBL int on //c
+        STA     $C05B   ; Enable VBL int
 -       LDA     $C019
+        STA     $C079   ; Reset VBL int on //c
         BMI     -
 -       LDA     $C019
         BPL     -
+        STA     $C05A   ; Disable VBL int on //c
+        STA     $C078   ; Disable IOU access on //c
+        PLP
         RTS
 end
-// Wait for VBL on IIc is entirely different from others.
-// Setup, one-time *only* if polling will be used exclusively.
-// Otherwise requires restoring the mode on exit,
-// and setting up per-use instead.
-//   [php]
-//   sei         ; otherwise interrupt is still raised
-//   sta   $C07F ; enable access to VBL register
-//   sta   $C05B ; enable VBL polling
-//   sta   $C07E ; disable access to VBL register
-//
-// wait for VBL:
-// - bit   $C019
-//   bpl   -
-//   lda   $C070 ; $c019 bit 7 is sticky, reset it
-//
-// To allow other methods of VBL, restore access:
-// - bit   $C019
-//   bpl   -
-//   lda   $C070 ; $c019 bit 7 is sticky, reset it
-//   sta   $C07F ; enable access to VBL register
-//   sta   $C05A ; disable VBL polling
-//   sta   $C07E ; disable access to VBL register
-//   [plp]
-
 //
 // Clear the buffer
 //

src/libsrc/apple/grlib.pla

@@ -407,6 +407,28 @@ asm _grFillTile
         RTS
 end
 //
+// Wait for VLB
+//
+export asm grVLB#0
+        LDA     $BF98
+        AND     #$C0
+        CMP     #$80
+        BNE     +
+        PHP
+        SEI
+        STA     $C079   ; Enable IOU access and reset VBL int on //c
+        STA     $C05B   ; Enable VBL int
+-       LDA     $C019
+        STA     $C079   ; Reset VBL int on //c
+        BMI     -
+-       LDA     $C019
+        BPL     -
+        STA     $C05A   ; Disable VBL int on //c
+        STA     $C078   ; Disable IOU access on //c
+        PLP
++       RTS
+end
+//
 // Clear the buffer
 //
 export def grClear(clr)#0
@@ -458,6 +480,7 @@ export def grShow(page)#1
     return page ^ 1
 end
 export def grSwap#0
+    //vlbWait
     ^(showpage1 + drawpage)
     drawpage   = drawpage ^ 1
     drawbuff = grbuff[drawpage]

src/toolsrc/ed.pla

@@ -994,22 +994,26 @@ def keyin3
 end
 def keyin2e
     byte key, vbl
-    ^$C07F = 0 // IOUDis: off
-    ^$C05B     // Enable VBL Ints on a //c
+    ^$C079 = 0 // IOU enable and clear VBL int on //c
+    ^$C05B = 0 // Enable VBL Ints on //c
+    vbl    = ^$C019
     repeat
-        vbl = ^$C019
         if flags & showcurs
             if flash == 0
                 ^cursptr = curschr
             elsif flash == 128
                 ^cursptr = underchr
             fin
-            if vbl ^ ^$C019; flash = flash + 8; fin
+            if vbl ^ ^$C019
+                flash = flash + 8
+                vbl = ^$C019
+                ^$C079 = 0 // Clear VBL int on //c
+            fin
         fin
         key = ^keyboard
     until key >= 128
-    ^$C05A     // Disable VBL Ints on a //c
-    ^$C07E = 0 // IOUDis: on
+    ^$C05A = 0 // Disable VBL Ints on //c
+    ^$C078 = 0 // IOU disable on //c
     ^keystrobe
     if ^pushbttn2 & 128 // Closed Apple pressed
         when key