Complete redesign of the CBM610 support.

Use wrappers to call the kernal in bank 15 instead of implementing kernal
functionality within the cc65 libs (eats performance but is much smaller and
simpler).
Improved startup/shutdown code allows a return to the system bank without
calling the BASIC cold start vector.


git-svn-id: svn://svn.cc65.org/cc65/trunk@2793 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm610/cgetc.s

@@ -5,44 +5,69 @@
 ;
 
 	.export	   	_cgetc
-	.import	   	plot, write_crtc
+	.import	   	plot, write_crtc, sys_bank, restore_bank
 	.import	   	cursor
+        .import         sysp0: zp, sysp3: zp
 
 	.include   	"cbm610.inc"
 
 
-_cgetc:	lda    	KeyIndex	; Get number of characters
+_cgetc:	lda     IndReg
+        pha
+        lda     #$0F
+        sta     IndReg          ; Switch to the system bank
+
+        ldy     #$D1
+        lda     (sysp0),y       ; Get number of keys in keyboard buffer
 	bne	L2 	  	; Jump if there are already chars waiting
 
 ; Switch on the cursor if needed
 
        	lda	cursor
-       	beq	L1 	    	; Jump if no cursor
+       	beq    	L0 	    	; Jump if no cursor
 
        	jsr	plot		; Set the current cursor position
+        ldy     #$D4
+        lda     (sysp0),y       ; Get the cursor format
        	ldy	#10
-       	lda	Config 	       	; Cursor format
-       	jsr	write_crtc	; Set the cursor formar
+       	jsr	write_crtc	; Set the cursor format
 
-L1:    	lda	KeyIndex
-       	beq	L1
+L0:     ldy     #$D1
+L1:     lda     (sysp0),y       ; Get the number of keys in the buffer
+       	beq	L1              ; Wait until we have some keys
 
        	ldy	#10
        	lda	#$20		; Cursor off
        	jsr	write_crtc
 
-L2:    	ldx    	#$00		; Get index
-       	ldy	KeyBuf		; Get first character in the buffer
-       	sei
-L3:    	lda	KeyBuf+1,x	; Move up the remaining chars
-       	sta	KeyBuf,x
-       	inx
-       	cpx	KeyIndex
-       	bne	L3
-       	dec	KeyIndex
-       	cli
+L2:     ldy     #$D1
+        lda     (sysp0),y       ; Get number of chars in buffer
+        tax
+        ldy     #$AB
+        lda     (sysp3),y       ; Get first char from keyboard buffer
+        sta     c               ; Save for return
+        dex
+        txa
+        ldy     #$D1
+        sta     (sysp0),y
+        sei
+        jmp     L4
+L3:     iny
+        lda     (sysp3),y
+        dey
+        sta     (sysp3),y
+        iny
+L4:     dex
+        bpl     L3       
+        cli
+
+        pla
+        sta     IndReg          ; Restore old segment
 
        	ldx	#$00		; High byte
-       	tya			; First char from buffer
+       	lda     c               ; First char from buffer
        	rts
 
+.bss
+
+c:      .byte   0