Changed the solution for the PLOT problem with old -02 kernals to that used

for the VIC20: PLOT is not an kernal entry but a library function that will 
do the right stuff. This makes it work with other stuff that calls PLOT, too.


git-svn-id: svn://svn.cc65.org/cc65/trunk@4249 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/c64/Makefile

@@ -58,6 +58,7 @@ OBJS = 	_scrsize.o     	 	\
 	joy_stddrv.o		\
        	kbhit.o	       	 	\
         kernal.o                \
+        kplot.o                 \
         mainargs.o              \
         mcbdefault.o            \
         mouse_stddrv.o          \

libsrc/c64/cputc.s

@@ -84,20 +84,12 @@ L11:	ora	#$40
 
 
 
-; Set cursor position, calculate RAM pointers. Because kernal -02 doesn't
-; update the color RAM pointer, we have to do that manually here.
+; Set cursor position, calculate RAM pointers.
 
 plot:	ldy	CURS_X
 	ldx	CURS_Y
 	clc
-       	jsr	PLOT		; Set the new cursor
-        lda     SCREEN_PTR      ; Low byte of color RAM ...
-        sta     CRAM_PTR        ; ... is same as text screen pointer
-        lda     SCREEN_PTR+1    ; While high byte of color RAM
-        and     #$03
-        ora     #$D8            ; ... needs to be adjusted
-        sta     CRAM_PTR+1
-        rts
+       	jmp     PLOT		; Set the new cursor
 
 
 

libsrc/c64/kernal.s

@@ -41,7 +41,6 @@
         .export         CLALL
         .export         UDTIM
         .export         SCREEN
-        .export         PLOT
         .export         IOBASE
 
 
@@ -85,6 +84,5 @@ GETIN		= $FFE4
 CLALL		= $FFE7
 UDTIM		= $FFEA
 SCREEN		= $FFED
-PLOT		= $FFF0
 IOBASE		= $FFF3
 

libsrc/c64/kplot.s

@@ -0,0 +1,21 @@
+;
+; Ullrich von Bassewitz, 2002-12-09, 2009-09-27
+;
+; PLOT replacement function for the C64. The kernal function in the -02 kernals
+; does not set the pointer to the color RAM correctly, so we need to fix that.
+;
+
+        .export         PLOT
+
+
+.proc   PLOT
+
+        bcs     @L1
+        jsr     $FFF0                   ; Set cursor position
+        jmp     $EA24                   ; Set pointer to color RAM
+
+@L1:    jmp     $FFF0                   ; Get cursor position
+
+.endproc
+
+