New kbhit and cgetc functions from Karri

git-svn-id: svn://svn.cc65.org/cc65/trunk@3295 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/lynx/Makefile

@@ -45,12 +45,14 @@ CFLAGS	= -Osir -g -T -t $(SYS) --forget-inc-paths -I . -I ../../include
 #--------------------------------------------------------------------------
 # Object files
 
-OBJS =	crt0.o          \
+OBJS =	cgetc.o         \
+        crt0.o          \
 	ctype.o		\
         eeprom.o        \
         extzp.o         \
         framerate.o     \
 	getenv.o	\
+        kbhit.o         \
 	mainargs.o	\
 	sysuname.o	\
         upload.o

libsrc/lynx/cgetc.s

@@ -0,0 +1,41 @@
+;
+; Karri Kaksonen, 2004-11-01
+;
+; char cgetc (void);
+;
+
+       	.export		_cgetc
+       	.import		_kbhit
+       	.import		KBBUF
+
+; --------------------------------------------------------------------------
+; The Atari Lynx has a very small keyboard - only 3 keys
+; Opt1, Opt2 and Pause.
+; But the designers have decided that pressing Pause and Opt1 at the
+; same time means Restart and pressing Pause and Opt2 means Flip screen.
+
+; For "easter egg" use I have also included all three keys pressed '?'
+; and Opt1 + Opt2 pressed '3'.
+; So the keyboard returns '1', '2', '3', 'P', 'R', 'F' or '?'.
+
+_cgetc:
+    	jsr    	_kbhit	       	; Check for char available
+        tax                     ; Test result
+	beq	_cgetc
+
+	ldx	#5		; Wait for some time... 0.2 seconds or so.
+@L1:	ldy	#255
+@L2:	lda	#255
+@L3:	dec
+	bne	@L3
+	dey
+	bne	@L2
+	dex
+	bne	@L1
+
+    	jsr    	_kbhit	       	; Check for double pressed buttons
+	lda	KBBUF
+	stz	KBBUF
+       	ldx	#0
+       	rts
+

libsrc/lynx/kbhit.s

@@ -0,0 +1,79 @@
+;
+; Karri Kaksonen, 2004-11-01
+;
+; unsigned char kbhit (void);
+;
+
+	.export		_kbhit
+	.export		KBBUF
+	.import		return0, return1
+
+; --------------------------------------------------------------------------
+; The Atari Lynx has a very small keyboard - only 3 keys
+; Opt1, Opt2 and Pause.
+; But the designers have decided that pressing Pause and Opt1 at the
+; same time means Restart and pressing Pause and Opt2 means Flip screen.
+
+; For "easter egg" use I have also included all three keys pressed '?'
+; and Opt1 + Opt2 pressed '3'.
+; So the keyboard returns '1', '2', '3', 'P', 'R', 'F' or '?'.
+
+	.data
+KBBUF:		.byte	0
+DEBOUNCE:	.byte	0	; Contains char until key is freed
+
+	.code
+_kbhit:
+	lda	$FCB1		; Read the Pause key
+	and	#1
+	bne	@L4
+	lda	$FCB0		; No Pause pressed
+	and	#$0c
+	bne	@L1
+	stz	DEBOUNCE	; No keys pressed at all
+	lda	KBBUF		; But we may have some old key in the buffer
+	bne	@L9
+	jmp	return0		; No key has been pressed
+@L1:
+	cmp	#$0c
+	bne	@L2
+	ldx	#'3'		; Opt 1 + Opt 2 pressed
+	bra	@L8
+@L2:
+	cmp	#$08
+	bne	@L3
+	ldx	#'1'		; Opt 1 pressed
+	bra	@L8
+@L3:
+	ldx	#'2'		; Opt 2 pressed
+	bra	@L8
+@L4:
+	lda	$FCB0
+	and	#$0c
+	bne	@L5
+	ldx	#'P'		; Pause pressed
+	bra	@L8
+@L5:
+	cmp	#$0c
+	bne	@L6
+	ldx	#'?'	; Opt 1 + Opt 2 + Pause pressed
+	bra	@L8
+@L6:
+	cmp	#$08
+	bne	@L7
+	ldx	#'R'	; Restart pressed
+	bra	@L8
+@L7:
+	ldx	#'F'	; Flip pressed
+@L8:
+	lda	KBBUF
+	bne	@L10
+	lda	DEBOUNCE
+	beq	@L10
+	jmp	return0	; Return no key pressed until keys are released
+@L10:
+	stx	KBBUF
+	sta	DEBOUNCE
+@L9:	jmp	return1
+
+