finished MEGA65 screen scrolling

src/aliases/,aliases_ram_lowmem_m65.s

@@ -51,7 +51,7 @@
 	.label M65_TXTWIN_Y0    = $58F //            text window - top-left Y coordinate, starting from 0
 	.label M65_TXTWIN_X1    = $590 //            text window - bottom-right X coordinate + 1
 	.label M65_TXTWIN_Y1    = $591 //            text window - bottom-right Y coordinate + 1
-	.label M65_TXTROW_OFF   = $592 // $592-$593  offset to the current text row
+	.label M65_TXTROW_OFF   = $592 // $592-$593  offset to the current text row from the viewport start
 	                               // $594-$5EB  -- UNUSED --
 	.label M65_DMAGIC_LIST  = $5EF // $5EF-$5FF  reserved for DMAgic list, 17 bytes
 	.label M65_RS232_INBUF  = $600 // $600-$6FF  -- reserved for RS-232 input buffer --

src/kernal/screen_m65/mega65_chrout_screen.s

@@ -241,16 +241,49 @@ m65_chrout_fix_scroll_up_scroll:
 
 	// Virtual screen is too small - we will lose one row
 
-	// XXX implement
+	// Calculate size of data to copy
 
-	// XXX set size
+	sec
+	lda M65_COLGUARD+0
+	sbc #$50
+	sta M65_DMAJOB_SIZE_0
+	lda M65_COLGUARD+1
+	sbc #$00
+	sta M65_DMAJOB_SIZE_1
 
-	// jsr m65_screen_dmasrcdst_screen
-	// XXX add $50 to DST
-	// jsr m65_dmagic_oper_copy
+	// Scroll up screen memory
 
-	// jsr m65_screen_dmasrcdst_color
-	// XXX add $50 to DST
-	// jsr m65_dmagic_oper_copy
+	jsr m65_screen_dmasrcdst_screen
+	jsr m65_screen_dmasrc_add_row
+	jsr m65_dmagic_oper_copy
+
+	// Scroll up color memory
+
+	jsr m65_screen_dmasrcdst_color
+	jsr m65_screen_dmasrc_add_row
+	jsr m65_dmagic_oper_copy
+
+	// Clear the last row - color and screen memory
+
+	phz
+
+	jsr m65_helper_scrlpnt_color
+	lda COLOR
+	and #$0F
+	ldz #$4F
+!:
+	sta_lp (M65_LPNT_SCR), z
+	dez
+	bpl !-
+
+	jsr m65_helper_scrlpnt_to_screen
+	lda #$20
+	ldz #$4F
+!:
+	sta_lp (M65_LPNT_SCR), z
+	dez
+	bpl !-
+
+	plz
 
 	rts

src/kernal/screen_m65/mega65_clrwin.s

@@ -22,6 +22,8 @@ M65_CLRWIN:
 
 	// First initialize both pointers
 
+	// XXX use m65_helper_scrlpnt_color and m65_helper_scrlpnt_to_screen instead
+
 	clc
 	lda M65_COLVIEW+0
 	adc M65_SCRBASE+0

src/kernal/screen_m65/mega65_screen_helpers.s

@@ -57,3 +57,15 @@ m65_screen_dmasrcdst_color:
 	sta M65_DMAJOB_DST_2
 	lda #$0F
 	jmp_8 !-
+
+
+m65_screen_dmasrc_add_row:
+
+	clc
+	lda M65_DMAJOB_SRC_0
+	adc #$50
+	sta M65_DMAJOB_SRC_0
+	bcc !+
+	inc M65_DMAJOB_SRC_1
+!:
+	rts