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/plus4/_scrsize.s

@@ -4,11 +4,18 @@
 ; Screen size variables
 ;
 
-	.export		xsize, ysize
+	.export	   	screensize
 
-.data             
+; We will return the values directly instead of banking in the ROM and calling
+; SCREEN which is a lot more overhead in code size and CPU cycles.
+
+.proc   screensize
+
+        ldx     #40
+        ldy     #25
+        rts
+
+.endproc
 
-xsize: 	.byte   40
-ysize:	.byte   25
 
 

libsrc/plus4/cputc.s

@@ -8,7 +8,6 @@
     	.export		_cputcxy, _cputc, cputdirect, putchar
 	.export		newline, plot
 	.import		popa, _gotoxy
-	.import		xsize
         .import         PLOT
 
 	.include	"plus4.inc"
@@ -50,7 +49,7 @@ cputdirect:
 
 advance:
         iny
-        cpy     xsize
+        cpy     #XSIZE
         bne     L3
         jsr     newline         ; new line
         ldy     #0              ; + cr
@@ -59,13 +58,13 @@ 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

libsrc/plus4/plus4.inc

@@ -41,6 +41,12 @@ IRQVec		= $0314
 BRKVec		= $0316
 NMIVec		= $0318
 
+; ---------------------------------------------------------------------------
+; Screen size
+
+XSIZE           = 40
+YSIZE           = 25
+
 ; ---------------------------------------------------------------------------
 ; I/O