From 306770331a85928e9dbd56e5352c95f977c9ba8e Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Mon, 21 Sep 2020 23:39:25 +0200
Subject: [PATCH] added cx16 txt.scroll_left

---
 compiler/res/prog8lib/cx16/textio.p8 | 43 +++++++++++++++-------------
 examples/test.p8                     | 17 +++++++----
 2 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/compiler/res/prog8lib/cx16/textio.p8 b/compiler/res/prog8lib/cx16/textio.p8
index 15cd2c765..b22ce31c7 100644
--- a/compiler/res/prog8lib/cx16/textio.p8
+++ b/compiler/res/prog8lib/cx16/textio.p8
@@ -161,34 +161,37 @@ asmsub  scroll_left  (ubyte dummy @ Pc) clobbers(A, Y)  {
 	    phx
 	    jsr  c64.SCREEN
 	    dex
-        stx  _nextrow+1   ; number of columns to scroll
+	    stx  _lx+1
         dey
         sty  P8ZP_SCRATCH_B1    ; number of rows to scroll
-        stz  cx16.VERA_CTRL
-        stz  cx16.VERA_ADDR_H
 
-_nextrow
-        ldx  #0     ; modified
+_nextline
+        stz  cx16.VERA_CTRL     ; data port 0: source column
+        lda  #%00010000         ; auto increment 1
+        sta  cx16.VERA_ADDR_H
+        lda  #2
+        sta  cx16.VERA_ADDR_L   ; begin in column 1
+        ldy  P8ZP_SCRATCH_B1
+        sty  cx16.VERA_ADDR_M
+        lda  #1
+        sta  cx16.VERA_CTRL     ; data port 1: destination column
+        lda  #%00010000         ; auto increment 1
+        sta  cx16.VERA_ADDR_H
         stz  cx16.VERA_ADDR_L
         sty  cx16.VERA_ADDR_M
 
--       lda  cx16.VERA_DATA0    ; char
-        inc  cx16.VERA_ADDR_L
-        ldy  cx16.VERA_DATA0    ; color
-        dec  cx16.VERA_ADDR_L
-        dec  cx16.VERA_ADDR_L
-        dec  cx16.VERA_ADDR_L
-        sta  cx16.VERA_DATA0
-        inc  cx16.VERA_ADDR_L
-        sty  cx16.VERA_DATA0
-        inc  cx16.VERA_ADDR_L
-        inc  cx16.VERA_ADDR_L
-        inc  cx16.VERA_ADDR_L
+_lx     ldx  #0                ; modified
+-       lda  cx16.VERA_DATA0
+        sta  cx16.VERA_DATA1    ; copy char
+        lda  cx16.VERA_DATA0
+        sta  cx16.VERA_DATA1    ; copy color
         dex
-        bpl  -
+        bne  -
         dec  P8ZP_SCRATCH_B1
-        ldy  P8ZP_SCRATCH_B1
-        bpl  _nextrow
+        bpl  _nextline
+
+        lda  #0
+        sta  cx16.VERA_CTRL
 	    plx
 	    rts
 	}}
diff --git a/examples/test.p8 b/examples/test.p8
index bd3719752..c4d979d1a 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -1,26 +1,31 @@
 %import syslib
 ; %import graphics
 %import textio
-; %zeropage basicsafe
+%zeropage basicsafe
 
 
 main {
 
     sub start()  {
 
+        ; cx16.screen_set_mode(128)
+
+        ubyte width = txt.width()
+        ubyte height = txt.height()
+
         ubyte x
         ubyte y
-        for y in 0 to txt.DEFAULT_HEIGHT-1 {
-            for x in 0 to txt.DEFAULT_WIDTH-1 {
+        for y in 0 to height-1 {
+            for x in 0 to width-1 {
                 txt.setchr(x,y,x+y)
             }
         }
 
-        repeat txt.DEFAULT_WIDTH {
-            txt.setcc(txt.DEFAULT_WIDTH-1, rnd() % txt.DEFAULT_HEIGHT, 81, 2)
+        repeat width {
+            txt.setcc(width-1, rnd() % height, 81, 2)
             txt.scroll_left(true)
 
-            repeat 2000 {
+            repeat 1000 {
                 x++
             }
         }