From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Thu, 8 Aug 2002 12:27:40 +0000 (+0000)
Subject: New, shorter readjoy function
X-Git-Tag: V2.12.0~2245
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=76ee9a1f66634c9784c9c56656366290b55d1af8;p=cc65

New, shorter readjoy function


git-svn-id: svn://svn.cc65.org/cc65/trunk@1382 b7a2c559-68d2-44c3-8de9-860c34a00d81
---

diff --git a/libsrc/vic20/readjoy.s b/libsrc/vic20/readjoy.s
index a3cd1edde..9aec6bd49 100644
--- a/libsrc/vic20/readjoy.s
+++ b/libsrc/vic20/readjoy.s
@@ -5,69 +5,39 @@
 ; unsigned readjoy (unsigned char joy);
 ;
 
-     	.export		_readjoy
+        .export         _readjoy
 
-	.include	"vic20.inc"
+        .include        "vic20.inc"
 
 
-.proc	_readjoy
+; The current implemenation will ignore the joystick number because we do only
+; have one joystick
 
-	tax			; Joystick number into X
-	bne    	joy2
 
-; Read joystick 1
+.proc   _readjoy
 
-joy1:	lda     #$7F		
-	ldx     #$C3
-	sei			; necessary?
-	ldy	VIA1_DDRA
-	stx     VIA1_DDRA
-	ldx	VIA1_JOY
-	sty	VIA1_DDRA
-	ldy	VIA2_DDRB
-	sta     VIA2_DDRB
-	lda	VIA2_JOY	; sw3 happens to be the 7th bit (i.e negative)
-	sty	VIA2_DDRB
-	cli			; necessary?
-; all this mess below tries to normalize the returned results (see joystick.h)
-; by shifting bits around and inserting switch3 (right).
-; easier (and far smaller) would have been just to return the bits where they
-; lay and just #ifdef different joystick constants for the Vic20.
-	bmi     s3_off		; must stay valid from the VIA2_JOY load
-	txa                     ; state: sw3 on, fire ?
-	and	#$20		; find out if fire has been pressed
-	bne	f_off1
-	txa			; state: sw3 on, fire on
-	lsr
-	lsr
-	and	#$07
-	eor	#$1F		
-	rts
-f_off1:	txa                     ; state: sw3 on, fire off
-	lsr
-	lsr
-	and	#$07 
-	eor	#$0F		
-	rts
-s3_off: txa			; state: sw3 off, fire ?
-	and	#$20		; find out if fire has been pressed
-	bne	f_off2		; yeah, that's just about my sentiment by now
-	txa			; state: sw3 off, fire on
-	lsr
-	lsr
-	and	#$07
-	eor	#$17		
-	rts
-f_off2:	txa			; state: sw3 off, fire off
-	lsr
-	lsr
-	and	#$07 
-	eor	#$07		
-	rts
- 
-; Read joystick 2 + (just return joy1)
+        lda     #$C3            ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
+        ldx     #$7F            ; mask for VIA2 JOYBIT: sw3
+        sei                     ; necessary?
 
-joy2:	jmp	joy1		; stub for more joysticks (pointless?) 
+        ldy     VIA1_DDRA       ; remember the state of DDRA
+        sta     VIA1_DDRA       ; set JOYBITS on this VIA for input
+        lda     VIA1_JOY        ; read JOYBITS: sw0,sw1,sw2,sw4
+        sty     VIA1_DDRA       ; restore the state of DDRA
+        and     #$3C            ; Mask relevant bits...
+        sta     tmp1            ; ...and save for later
+
+        ldy     VIA2_DDRB       ; remember the date of DDRB
+        stx     VIA2_DDRB       ; set JOYBITS on this VIA for input
+        lda     VIA2_JOY        ; read JOYBIT: sw3
+        sty     VIA2_DDRB       ; restore the state of DDRB
+
+        cli                     ; necessary?
+        and     #$80            ; Mask sw3
+        ora     tmp1            ; Get sw0, sw1, sw2, sw4
+        eor     #$BC            ; Active states are inverted
+
+        rts
 
 .endproc