From c23f8cef4f5cb9169b41d548291769988f4f3f43 Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Sun, 21 Apr 2019 21:59:06 +0930
Subject: [PATCH] implement core of delete char in chrout

---
 c64/kernal/,aliases.s |  2 +-
 c64/kernal/chrout.s   | 38 +++++++++++++++++++++++++++++++-------
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/c64/kernal/,aliases.s b/c64/kernal/,aliases.s
index 33ca4fd0..49441bdb 100644
--- a/c64/kernal/,aliases.s
+++ b/c64/kernal/,aliases.s
@@ -35,7 +35,7 @@
 	.alias current_screen_line_ptr $D1
 	.alias current_screen_x $D3
 	.alias quote_mode_flag $D4
-	.alias max_logical_line_length $D5
+	.alias logical_line_length $D5
 	.alias current_screen_y $D6
 	.alias last_printed_character_ascii $D7
 	.alias insert_mode $D8
diff --git a/c64/kernal/chrout.s b/c64/kernal/chrout.s
index 2e1855c8..ca412d81 100644
--- a/c64/kernal/chrout.s
+++ b/c64/kernal/chrout.s
@@ -88,17 +88,31 @@ delete_at_column_0:
 	jmp chrout_done
 not_row_0:
 	dec current_screen_y
-	lda screen_line_link_table,y
-	bpl line_not_linked_del
-	lda #79
-	.byte $2c 		; BIT absolute mode, which we use to skip the next two instruction bytes
-line_not_linked_del:
-	lda #39
+	jsr get_current_line_logical_length
+	
 	sta current_screen_x
 	jsr calculate_screen_line_pointer
 	jmp chrout_done
 
-delete_non_zero_column:	
+delete_non_zero_column:
+	;; Copy rest of line down
+	jsr get_current_line_logical_length
+	ldy current_screen_x
+*
+	lda (current_screen_line_ptr),y
+	dey
+	sta (current_screen_line_ptr),y
+	iny
+	lda (current_screen_line_colour_ptr),y
+	dey
+	sta (current_screen_line_colour_ptr),y
+	iny
+	iny
+	cpy logical_line_length
+	bne -
+
+	dec current_screen_x
+	
 	jmp chrout_done
 	
 not_14:	
@@ -167,6 +181,16 @@ screen_grow_logical_line:
 	;; XXX - Scroll screen down to make space
 
 	rts
+
+get_current_line_logical_length:	
+	ldy current_screen_y
+	lda screen_line_link_table,y
+	bpl line_not_linked_del
+	lda #79
+	.byte $2c 		; BIT absolute mode, which we use to skip the next two instruction bytes
+line_not_linked_del:
+	lda #39
+	rts
 	
 screen_advance_to_next_line:
 	;;  Go to start of line