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/cputc.s

@@ -5,13 +5,13 @@
 ; void cputc (char c);
 ;
 
-    	.export	     	_cputcxy, _cputc, cputdirect, putchar
-	.export	     	newline, plot
-	.exportzp	CURS_X, CURS_Y
+    	.export	      	_cputcxy, _cputc, cputdirect, putchar
+	.export	      	newline, plot
 
-        .import         PLOT
-	.import		_gotoxy
-	.import	     	popa
+	.import	      	_gotoxy
+	.import	      	popa
+
+        .import         ktmp: zp, crtc: zp, CURS_X: zp, CURS_Y: zp, CharPtr: zp
 
 	.include     	"cbm610.inc"
 
@@ -79,13 +79,6 @@ L10:	and	#$7F
 L11:	ora	#$40
 	bne	cputdirect	; Branch always
 
-; Set cursor position, calculate RAM pointers
-
-plot:	ldy	CURS_X
-	ldx	CURS_Y
-	clc
-	jmp	PLOT
-
 ; Write one character to the screen without doing anything else, return X
 ; position in Y
 
@@ -99,4 +92,61 @@ putchar:
 	stx	IndReg
 	rts
 
+; Set cursor position, calculate RAM pointers
+
+plot:   ldx     CURS_Y
+        lda	LineLSBTab,x
+	sta	CharPtr
+	lda	LineMSBTab,x
+	sta	CharPtr+1
+
+	lda	IndReg
+	pha
+	lda	#$0F
+	sta	IndReg
+
+	ldy	#$00
+	clc
+	sei
+	sta	(crtc),y
+	lda	CharPtr
+	adc	CURS_X
+	iny
+	sta	(crtc),y
+	dey
+	lda	#$0E
+	sta	(crtc),y
+	iny
+	lda	(crtc),y
+	and	#$F8
+	sta	ktmp
+	lda	CharPtr+1
+	adc	#$00
+	and	#$07
+	ora	ktmp
+	sta	(crtc),y
+	cli
+
+	pla
+	sta	IndReg
+	rts
+
+; -------------------------------------------------------------------------
+; Low bytes of the start address of the screen lines
+
+.rodata
+
+LineLSBTab:
+        .byte   $00,$50,$A0,$F0,$40,$90,$E0,$30
+        .byte   $80,$D0,$20,$70,$C0,$10,$60,$B0
+        .byte   $00,$50,$A0,$F0,$40,$90,$E0,$30
+        .byte   $80
+; -------------------------------------------------------------------------
+; High bytes of the start address of the screen lines
+
+LineMSBTab:
+        .byte   $D0,$D0,$D0,$D0,$D1,$D1,$D1,$D2
+        .byte   $D2,$D2,$D3,$D3,$D3,$D4,$D4,$D4
+        .byte   $D5,$D5,$D5,$D5,$D6,$D6,$D6,$D7
+        .byte   $D7