added DEL key support to MEGA65 native text mode

src/aliases/,aliases_ram_lowmem_m65.s

@@ -52,7 +52,8 @@
 	.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 from the viewport start
-	                               // $594-$5EB  -- UNUSED --
+	.label M65_SCRCOLMAX    = $594 //            maximum allowed column
+	                               // $595-$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 --
 	.label M65_RS232_OUTBUF = $700 // $700-$7FF  -- reserved for RS-232 output buffer --

src/kernal/screen_m65/mega65_chrout_screen.s

@@ -270,7 +270,7 @@ m65_chrout_fix_scroll_up_scroll:
 	jsr m65_helper_scrlpnt_color
 	lda COLOR
 	and #$0F
-	ldz #$4F
+	ldz M65_SCRCOLMAX
 !:
 	sta_lp (M65_LPNT_SCR), z
 	dez
@@ -278,7 +278,7 @@ m65_chrout_fix_scroll_up_scroll:
 
 	jsr m65_helper_scrlpnt_to_screen
 	lda #$20
-	ldz #$4F
+	ldz M65_SCRCOLMAX
 !:
 	sta_lp (M65_LPNT_SCR), z
 	dez

src/kernal/screen_m65/mega65_chrout_screen_control.s

@@ -93,8 +93,6 @@ m65_chrout_screen_ESC:
 	nop
 m65_chrout_screen_BELL:
 	nop
-m65_chrout_screen_DEL:
-	nop
 m65_chrout_screen_GFX:
 	nop
 m65_chrout_screen_TXT:

src/kernal/screen_m65/mega65_chrout_screen_control_del.s

@@ -0,0 +1,102 @@
+// #LAYOUT# M65 KERNAL_1 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+// 'DEL' key support
+
+m65_chrout_screen_DEL:
+
+	// First check for window mode
+
+	lda M65_SCRWINMODE
+	bmi m65_chrout_screen_DEL_winmode
+
+	// Not a window mode; check if we are in the first column
+
+	lda M65__TXTCOL
+	beq m65_chrout_screen_DEL_1stcol
+
+	// Not a window mode, not a first column - we can safely
+	// delete the character and sroll back the rest of the row
+
+	phz
+
+	jsr m65_helper_scrlpnt_color
+	jsr m65_chrout_screen_DEL_copy
+	
+	ldz M65_SCRCOLMAX
+	lda COLOR
+	and #$0F
+	sta_lp (M65_LPNT_SCR), z
+
+	jsr m65_helper_scrlpnt_to_screen
+	jsr m65_chrout_screen_DEL_copy
+
+	ldz M65_SCRCOLMAX
+	lda #$20
+	sta_lp (M65_LPNT_SCR), z
+
+	plz
+
+	// End by moving cursor one position left
+
+	jmp m65_chrout_screen_CRSR_LEFT
+
+m65_chrout_screen_DEL_copy:
+
+	ldz M65__TXTCOL
+	dez
+!:
+	cpz M65_SCRCOLMAX
+	beq !+
+
+	inz
+	lda_lp (M65_LPNT_SCR), z
+	dez 
+	sta_lp (M65_LPNT_SCR), z
+	
+	inz
+	jmp_8 !-
+!:
+	rts
+
+
+m65_chrout_screen_DEL_1stcol:
+
+	// Start by moving one position left
+
+	jsr m65_chrout_screen_CRSR_LEFT
+
+	// If we are still in the first column - nothing to do
+
+	lda M65__TXTCOL
+	beq !+
+
+	// Deleta character under cursor
+
+	phz
+
+	jsr m65_helper_scrlpnt_color
+	ldz M65__TXTCOL
+
+	lda COLOR
+	and #$0F
+	sta_lp (M65_LPNT_SCR), z
+
+	jsr m65_helper_scrlpnt_to_screen
+	lda #$20
+	sta_lp (M65_LPNT_SCR), z
+
+	plz
+
+	// End of character deletion
+!:
+	jmp m65_chrout_screen_done
+
+
+m65_chrout_screen_DEL_winmode:
+
+	// XXX provide implementation for window mode
+
+	jmp m65_chrout_screen_done
+

src/kernal/screen_m65/mega65_scrmodeset.s

@@ -88,8 +88,9 @@ m65_scrmodeset_internal: // entry point for M65_MODE65
 	stx VIC_COLPTR+1
 
 	// Set the following locations:
-	// - M65_SCRGUARD, M65_COLGUARD    - for max lines of virtual screen
-	// - M65_COLVIEWMAX                - as above, but depending on the mode
+	// - M65_SCRGUARD, M65_COLGUARD    - guards for virtual screen end
+	// - M65_COLVIEWMAX                - guard for viewport start
+	// - M65_SCRCOLMAX                 - maximum allowed column
 
 	ldx #<(MEMCONF_SCRBASE + 80 * MEMCONF_SCRROWS)
 	stx M65_SCRGUARD+0
@@ -106,5 +107,8 @@ m65_scrmodeset_internal: // entry point for M65_MODE65
 	sta M65_COLVIEWMAX+0
 	lda m65_scrtab_colviewmax_hi, x
 	sta M65_COLVIEWMAX+1
+	lda m65_scrtab_txtwidth,x
+	dec_a
+	sta M65_SCRCOLMAX
 
 	rts