work on character inserting

STATUS.md

@@ -4,7 +4,7 @@
 Here are the features of the Open ROMs not found in the original ROMs from the 80s (many of them are [configurable](CONFIG.md) during compilation):
 
 
-* improved keyboard scanning, resistant to ghosting and joystick interference (one variant even supports multi-keyy rollover), supports additional C128 keys
+* improved keyboard scanning, resistant to ghosting and joystick interference (one variant even supports multi-key rollover), supports additional C128 keys
 * joystick can be used to move text cursor
 * pre-defined function keys
 

c64/kernal/keyboard/chrin_keyboard.s

@@ -90,8 +90,7 @@ chrin_enter:
 	sta LXSP+1
 
 	// Calculate length
-	jsr screen_get_current_line_logical_length
+	jsr screen_get_logical_line_end_ptr
-	tay
 	iny
 !:	dey
 	bmi empty_line

c64/kernal/screen/chrout_screen_del.s

@@ -3,10 +3,7 @@
 // CHROUT routine - screen support, DEL key handling
 //
 
-chrout_screen_DEL:
-	jmp chrout_screen_done
 
-/* YYY disabled for rework
 chrout_screen_DEL:
 
 	// In insert mode it embeds control character
@@ -14,6 +11,14 @@ chrout_screen_DEL:
 	beq !+
 	jmp chrout_screen_quote
 !:
+
+
+
+	jmp chrout_screen_done
+
+/* YYY disabled for rework
+chrout_screen_DEL:
+
 	ldx PNTR
 	bne chrout_screen_del_column_non_0
 

c64/kernal/screen/chrout_screen_ins.s

@@ -3,39 +3,30 @@
 // CHROUT routine - screen support, INS key handling
 //
 
-chrout_screen_INS:
-	jmp chrout_screen_done
 
-/* YYY disabled for rework
+// YYY does not work properly on growing logical line
+// YYY implement LNMX
+
+
 chrout_screen_INS:
 
-	// Insert (shift-DELETE)
+	// First check if last character of the line is space
 	
-	// Abort if line already max length, ie 79th char is not a space
+	jsr screen_check_space_ends_line
-	jsr screen_get_current_line_logical_length
+	beq chrout_screen_ins_possible
-	cmp #79
-	bne !+
-	tay
-	lda (PNT),y
-	cmp #$20
-	beq !+
 
-	// Line is too long to extend
+	// Not space, try to grow logical line and check once again
-	jmp chrout_screen_done
-
-!:
-	// Work out if line needs to be expanded, and if so expand it
-	ldy #39
-	lda (PNT),y
-	cmp #$20
-	beq !+
 
 	jsr screen_grow_logical_line
+	jsr screen_check_space_ends_line
+	bne_far chrout_screen_done
 	
-!:	
+	// FALLTROUGH
-	// Shuffle chars towards end of line
+
-	jsr screen_get_current_line_logical_length
+chrout_screen_ins_possible:
-	tay
+
+	// Move chars towards end of the line
+	jsr screen_get_logical_line_end_ptr
 !:
 	// Note: While the following routine is obvious to any skilled
 	// in the art as the most obvious simple and efficient solution,
@@ -43,7 +34,7 @@ chrout_screen_INS:
 	// in a relatively long verbatim stretch of bytes when compared to
 	// the C64 KERNAL.  Thus we have swapped the order, just to reduce
 	// the potential for any argument of copyright infringement, even
-	// though we really don't believe that the routine can be copyrighted
+	// though we really do not believe that the routine can be copyrighted
 	// due to the lack of creativity.
 	dey
 	lda (USER),y
@@ -63,7 +54,6 @@ chrout_screen_INS:
 
 	// Put space in the inserted gap
 	lda #$20
-	sta (PNT),y
+	sta (PNT), y
 
 	jmp chrout_screen_done
-*/

c64/kernal/screen/screen_check_space_ends_line.s

@@ -0,0 +1,8 @@
+
+screen_check_space_ends_line:
+
+	jsr screen_get_logical_line_end_ptr
+	lda (PNT), y
+	cmp #$20
+	
+	rts

c64/kernal/screen/screen_get_current_line_logical_length.s

@@ -1,17 +0,0 @@
-
-screen_get_current_line_logical_length:
-	rts
-
-/* YYY disabled for rework
-
-screen_get_current_line_logical_length:
-	ldy TBLX
-	lda LDTBL,y
-	bpl !+
-	lda #79
-	.byte $2c 		// BIT absolute mode, which we use to skip the next two instruction bytes
-!:
-	lda #39
-	sta LNMX
-	rts
-*/

c64/kernal/screen/screen_get_logical_line_end_ptr.s

@@ -0,0 +1,26 @@
+
+
+screen_get_logical_line_end_ptr:
+
+	ldy TBLX
+	cpy #24
+	bcs screen_get_logical_line_end_39 // last line of the screen
+	
+	lda LDTBL, y
+	bpl screen_get_logical_line_end_39 // current line continues previous one
+	
+	iny
+	lda LDTBL, y
+	bmi screen_get_logical_line_end_39 // current line is not continued
+	
+	// FALLTROUGH
+	
+screen_get_logical_line_end_79:
+
+	ldy #79
+	rts
+	
+screen_get_logical_line_end_39:
+
+	ldy #39
+	rts

c64/kernal/screen/screen_grow_logical_line.s

@@ -1,5 +1,5 @@
 
-// YYY test all the cases!
+// YYY test all the cases, does not work correctly yet!
 
 
 screen_grow_logical_line_screen_up:

c64/kernal/screen/screen_normalize_xy.s

@@ -1,79 +0,0 @@
-
-//
-// Normalise X and Y values
-// If X < 0, then make X = X + 40 (or 80, if previous line is linked)
-//
-
-/* YYY disabled for rework
-
-screen_normalize_xy:	
-
-	lda PNTR
-	bpl x_not_negative
-	dec TBLX
-	// Check that we didn't go backwards off the top of the screen
-	bpl !+
-	lda #0
-	sta TBLX
-
-!:	jsr screen_add_40_to_PNTR
-
-	// Check if line is linked, if so, add 40 again
-	ldy TBLX
-	lda LDTBL,y
-	bpl !+
-	jsr screen_add_40_to_PNTR
-!:
-
-x_not_negative:
-	// Work out if X is too big
-	ldy TBLX
-	lda LDTBL,y
-	bpl !+
-	lda #79
-	skip_2_bytes_trash_nvz
-!:	lda #39
-	cmp PNTR
-	bcs x_not_too_big
-
-	// X value is too big, so subtract 40 and increment Y
-	lda PNTR
-	sec
-	sbc #40
-	sta PNTR
-	inc TBLX
-
-x_not_too_big:
-
-	// Make sure Y isn't negative
-	lda TBLX
-	bpl !+
-	lda #0
-	sta TBLX
-!:
-	// Make sure Y isn't too large for absolute size of
-	// screen
-	cmp #24
-	bcc !+
-	lda #24
-	sta TBLX
-!:
-	// Make sure Y isn't too much for the screen, taking
-	// into account the line link table
-	ldy #24 		// max allowable line
-	ldx #0
-link_count_loop:
-	lda LDTBL,x
-	bpl !+
-	dey
-!:	inx
-	cpx #25
-	bne link_count_loop
-	tya
-	cmp TBLX
-	bcs y_ok
-	sta TBLX
-y_ok:
-	rts
-
-*/