Add VSYNC toggle

demos/sprites/App.Main.s

@@ -94,6 +94,22 @@ EvtLoop
                     lda        #$FFF8
                     sta        PlayerYVel
 :no_jump
+
+
+; Enable/disable v-sync
+                    lda        1,s
+                    bit        #$0400
+                    beq        :no_key_down
+                    and        #$007F
+                    cmp        #'v'
+                    bne        :not_v
+                    lda        #$0001
+                    eor        vsync
+                    sta        vsync
+:not_v
+:no_key_down
+
+
                     pla
                     and        #$007F                  ; Ignore the buttons for now
 
@@ -165,6 +181,7 @@ EvtLoop
                     bra        :do_render
 :not_l
 
+
 ; Update the camera position
 
 :do_render
@@ -178,8 +195,25 @@ EvtLoop
                     jsl        UpdateSprite           ; Move the sprite to this local position
 
 ; Let's see what it looks like!
-
+                    lda        vsync
+                    beq        :no_vsync
+:vsyncloop          jsl        GetVerticalCounter     ; 8-bit value
+                    cmp        ScreenY0
+                    bcc        :vsyncloop
+                    sec
+                    sbc        ScreenY0
+                    cmp        #8
+                    bcs        :vsyncloop
+                    lda        #1
+                    jsl        SetBorderColor
+:no_vsync
                     jsl        Render
+    
+                    lda        vsync
+                    beq        :no_vsync2
+                    lda        #0
+                    jsl        SetBorderColor
+:no_vsync2
 
 ; Update the performance counters
 
@@ -435,6 +469,8 @@ MovePlayerToOrigin
 qtRec               adrl       $0000
                     da         $00
 
+vsync               dw         $0000
+
                     PUT        ../shell/Overlay.s
                     PUT        gen/App.TileMapBG0.s
                     PUT        gen/App.TileSetAnim.s

src/Core.s

@@ -343,6 +343,7 @@ ClearKbdStrobe    sep       #$20
                   rts
 
 ; Read the keyboard and paddle controls and return in a game-controller-like format
+LastKey           db        0
 ReadControl       ENT
                   pea       $0000               ; low byte = key code, high byte = %------AB 
 
@@ -351,7 +352,7 @@ ReadControl       ENT
                   and       #$80
                   beq       :BNotDown
 
-                  lda       #1
+                  lda       #PAD_BUTTON_B
                   ora       2,s
                   sta       2,s
 
@@ -360,7 +361,7 @@ ReadControl       ENT
                   and       #$80
                   beq       :ANotDown
 
-                  lda       #2
+                  lda       #PAD_BUTTON_A
                   ora       2,s
                   sta       2,s
 
@@ -372,7 +373,19 @@ ReadControl       ENT
                   ora       1,s
                   sta       1,s
 
+                  cmpl      LastKey
+                  beq       :KbdDown
+                  stal      LastKey
+
+                  lda       #PAD_KEY_DOWN       ; set the keydown flag
+                  ora       2,s
+                  sta       2,s
+                  bra       :KbdDown
+
 :KbdNotDwn
+                  lda       #0
+                  stal      LastKey
+:KbdDown
                   rep       #$20
                   pla
                   rtl

src/Defs.s

@@ -119,6 +119,11 @@ SWAP_PALETTE_ENTRY     equ   $0004
 SET_DYN_TILE           equ   $0006
 CALLBACK               equ   $0010
 
+; ReadControl return value bits
+PAD_BUTTON_B           equ   $01
+PAD_BUTTON_A           equ   $02
+PAD_KEY_DOWN           equ   $04
+
 ; Tile constants
 TILE_ID_MASK           equ   $01FF
 TILE_SPRITE_BIT        equ   $8000                  ; Set if this tile intersects an active sprite

src/GTE.s

@@ -10,6 +10,8 @@ ReadControl        EXT
 ; Low-Level Functions
 SetPalette         EXT
 GetVBLTicks        EXT
+GetVerticalCounter EXT
+SetBorderColor     EXT
 
 ; Tilemap functions
 SetBG0XPos         EXT

src/Graphics.s

@@ -126,6 +126,9 @@ _ShadowOff
                  rep   #$20
                  rts
 
+GetVerticalCounter ENT
+                 jsr   _GetVBL
+                 rtl
 _GetVBL
                  sep   #$20
                  ldal  VBL_HORZ_REG