check trigger button (TRIGx); correctly report joystick count depending

on 5200 console version

libsrc/atari5200/joy/atr5200std.s

@@ -1,7 +1,7 @@
 ;
 ; Standard joystick driver for the Atari 5200.
 ;
-; Christian Groessler, 2014-05-12
+; Christian Groessler, 2014-05-28
 ;
 
         .include        "zeropage.inc"
@@ -44,12 +44,6 @@
         .addr   READJOY
         .addr   0               ; IRQ entry not used
 
-; ------------------------------------------------------------------------
-; Constants
-
-JOY_COUNT       = 4             ; Number of joysticks we support
-
-
 .code
 
 ; ------------------------------------------------------------------------
@@ -78,7 +72,12 @@ UNINSTALL:
 ;
 
 COUNT:
-        lda     #JOY_COUNT
+        lda     $FD32           ; check ROM version
+        cmp     #$E8
+        bne     @2port
+        lda     #4
+        .byte   $2C             ; bit opcode, eats the next 2 bytes
+@2port: lda     #2
         ldx     #0
         rts
 
@@ -90,14 +89,19 @@ CENTER	=	228 / 2
 SENSIVITY       = 16
 
 READJOY:
-        and     #3              ; fix joystick number
+        and     #3              ; put joystick number in range, just in case
+        tay
         asl     a
         tax                     ; Joystick number * 2 (0-6) into X, index into ZP shadow registers
+
         lda     #0              ; Initialize return value
+        cmp     TRIG0,y
+        bne     @notrg
+        lda     #$10            ; JOY_FIRE
 
 ; Read joystick
 
-	ldy	PADDL0,x	; get horizontal position
+@notrg: ldy     PADDL0,x        ; get horizontal position
         cpy     #CENTER-SENSIVITY
         bcs     @chkleft
 
@@ -115,16 +119,12 @@ READJOY:
         bcs     @chkdown
 
         ora     #1              ; JOY_UP
-	bne	@buttons
+        bne     @done
 
 @chkdown:
         cpy     #CENTER+SENSIVITY
-	bcc	@buttons
+        bcc     @done
 
         ora     #2              ; JOY_DOWN
 
-@buttons:
+@done:  rts
-	; @@@ TODO: BOTTON STATE
-
-	rts
-