Make screensize() fetch the values dynamically instead of using variables

that are set on startup. This is needed to support the C128, which can switch
the screen size at runtime.


git-svn-id: svn://svn.cc65.org/cc65/trunk@2042 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm510/_scrsize.s

@@ -4,12 +4,16 @@
 ; Screen size variables
 ;
 
-	.export	 	xsize, ysize
+	.export		screensize
 
-.rodata
-
-xsize: 	.byte	40
-ysize:	.byte	25
+        .include        "cbm510.inc"
 
+.proc   screensize
+
+        ldx     #XSIZE
+        ldy     #YSIZE
+        rts
+
+.endproc
 
 

libsrc/cbm510/cbm510.inc

@@ -192,6 +192,12 @@ MoniSegSave	     = $03f0
 wstvec		     = $03F8
 WstFlag		     = $03FA	; Warm start flag
 
+; ---------------------------------------------------------------------------
+; Screen size
+
+XSIZE           = 40
+YSIZE           = 25
+
 ;-----------------------------------------------------------------------------
 ; I/O Definitions
 

libsrc/cbm510/cputc.s

@@ -10,7 +10,6 @@
 
         .import         PLOT
 	.import		popa, _gotoxy
-	.import		xsize
 
 	.include	"cbm510.inc"
 
@@ -53,7 +52,7 @@ cputdirect:
 
 advance:
    	iny
-   	cpy	xsize
+   	cpy	#XSIZE
    	bne	L3
 	jsr	newline		; new line
    	ldy	#0    	  	; + cr
@@ -62,13 +61,13 @@ L3:	sty	CURS_X
 
 newline:
    	clc
-   	lda	xsize
+   	lda	#XSIZE
    	adc	SCREEN_PTR
    	sta	SCREEN_PTR
    	bcc	L4
    	inc	SCREEN_PTR+1
    	clc
-L4:	lda    	xsize
+L4:	lda    	#XSIZE
    	adc	CRAM_PTR
    	sta	CRAM_PTR
    	bcc	L5