From 9656dde9e3e6a3ab9fd178d78b8fd115b875829d Mon Sep 17 00:00:00 2001
From: uz <uz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Sun, 7 Mar 2010 13:37:58 +0000
Subject: [PATCH] Fix scrolling (again). The old code switched off scrolling
 completely, as a consequence it didn't work when write(FILENO_STDOUT, ...)
 was used. So we will have to disable scrolling on a per character basis in
 cputc.

git-svn-id: svn://svn.cc65.org/cc65/trunk@4617 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 libsrc/c128/cputc.s     | 41 ++++++++++++++++++++++-------------------
 libsrc/c128/videomode.s |  3 +--
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/libsrc/c128/cputc.s b/libsrc/c128/cputc.s
index 5442e9f57..d69170bce 100644
--- a/libsrc/c128/cputc.s
+++ b/libsrc/c128/cputc.s
@@ -7,15 +7,12 @@
 ;
 
     	.export	     	_cputcxy, _cputc, cputdirect, putchar
- 	.export	     	newline, plot
-        .constructor    initcputc
-        .destructor     donecputc
+    	.export	     	newline, plot
  	.import	     	popa, _gotoxy
         .import         PLOT
 
  	.include     	"c128.inc"
 
-cputdirect      = PRINT
 newline         = NEWLINE
 
 ;--------------------------------------------------------------------------
@@ -40,15 +37,26 @@ _cputc: cmp    	#$0A   		; CR?
 ; Printable char of some sort
 
 L2:	cmp	#' '
-       	bcc    	L4              ; Other control char
+       	bcc    	cputdirect      ; Other control char
     	tay
     	bmi	L5
     	cmp	#$60
     	bcc	L3
     	and	#$DF
-    	bne    	L4              ; Branch always
+       	bne    	cputdirect      ; Branch always
 L3: 	and	#$3F
-L4:     jmp     PRINT  		; Output character
+
+; Output one character to the screen. We will disable scrolling while doing so
+
+cputdirect:
+        ldx     SCROLL
+        stx     ScrollSave      ; Save scroll flag
+        ldx     #$C0
+        stx     SCROLL          ; Disable scrolling
+        jsr     PRINT           ; Call kernal entry point
+        ldx     ScrollSave
+        stx     SCROLL          ; Restore old scroll flag
+        rts
 
 ; Handle character if high bit set
 
@@ -56,9 +64,9 @@ L5:	and	#$7F
        	cmp    	#$7E  	  	; PI?
   	bne	L6
   	lda	#$5E  	  	; Load screen code for PI
-  	bne    	L4
+  	bne    	cputdirect
 L6:	ora	#$40
-  	bne	L4              ; Branch always
+  	bne	cputdirect      ; Branch always
 
 ; Carriage return
 
@@ -78,14 +86,9 @@ plot:	ldy	CURS_X
 putchar	= $CC2F
 
 ;--------------------------------------------------------------------------
-; Module constructor/destructor. Don't move the constructor into the INIT
-; segment, because it shares most of the code with the destructor.
-
-initcputc:
-	lda	#$C0
-        .byte   $2C
-donecputc:
-        lda     #$00
-	sta	SCROLL
-        rts
+; Data
+.bss
+
+ScrollSave:     .res    1       ; Save location for scroll byte
+
 
diff --git a/libsrc/c128/videomode.s b/libsrc/c128/videomode.s
index fd37b7b6a..d07df5160 100644
--- a/libsrc/c128/videomode.s
+++ b/libsrc/c128/videomode.s
@@ -22,8 +22,7 @@
         jsr     SWAPPER                 ; Toggle the mode
  	lda     #14
        	jsr     BSOUT                   ; Switch to lower case chars
-        lda     #$C0
-        sta     SCROLL                  ; Disable scrolling
+
         pla                             ; Get old mode into A
 
 ; Done, old mode is in A
-- 
2.39.5