; SuBEditor.
;
; Writen in Sux assembly by
; mr b0nk 500 <b0nk@b0nk.xyz>

.org $8000
reset:
	cps		; Reset the processor status register.
	lds.d #$2FFFF	; Reset the stack pointer.
	lea 0		; Reset E.
	ldy #0		; Reset Y.
	tyx		; Reset X.
	jsr init_heap	; Initialize the heap.
	mov sp, a	; Set the stack pointer to the end of RAM.
;	txs		;
	sub.d #STKSIZE	; Subtract the stack size, from the end of RAM.
	sta.q heapend	; Save the end of the heap.
	and #0		; Reset A.
	tax		; Reset X.
	clc		; Reset the carry flag, just in case.
	jsr init_tables	; Initialize the main tables.
;	jsr test_free	;
	jsr clr_scr	; Clear the screen.
	jsr pnt_strt	; Print the starting message.
	bra start	; Goto the start of the main program.


init_heap:
	lea HEAPORG	; Get the heap's starting point.
	ste.q heapptr	;
	mov d, e	;
	jsr findramend	; Find the end of the heap.
	rts		; End of init_heap.


init_tables:
	lea d, SCRSIZE	; Allocate SCRSIZE bytes of RAM for the screen buffer.
	jsr malloc	;
	sta.q buffer	;
	lea d, CMDSIZE	; Allocate CMDSIZE bytes of RAM for the command buffer.
	jsr malloc	;
	sta.q cmd_buf	;
	lea d, LWSIZE	; Allocate LWSIZE bytes of RAM for the linewrap table.
	jsr malloc	;
	sta.q bitabl	;
	rts		; End of init_tables.


;test_free:
;	inc step	;
;	mov.q d, bitabl	;
;	jsr free	;
;	mov.q d, buffer	;
;	jsr free	;
;	lea d, LWSIZE	; Allocate LWSIZE bytes of RAM for the linewrap table.
;	jsr malloc	;
;	sta.q bitabl	;
;	mov.q d, cmd_buf;
;	jsr free	;
;	lea d, SCRSIZE	; Allocate SCRSIZE bytes of RAM for the screen buffer.
;	jsr malloc	;
;	sta.q buffer	;
;	lea d, CMDSIZE	; Allocate CMDSIZE bytes of RAM for the command buffer.
;	jsr malloc	;
;	sta.q cmd_buf	;
;	and #0		; Reset A.
;	rts		; End of test_free.


clr_arr:
	pha.q			; Preserve A.
	and #0			; Reset A.
@loop:
	mov.q (d+s), a		; Clear 16 bytes.
	mov.q (d+s+8), a	;
	sub s, #16		; Subtract 16 from the size.
	bcs @loop		; We haven't reached the end, so keep looping.
@end:
	pla.q			; Restore A.
	rts			; End of clr_arr.


pnt_strt:
	lea d, ed_name	; Print the name of the editor.
	jsr print_str	;
	lea d, ver_str	; Print the version text.
	jsr print_str	;
	lea d, ed_ver	; Print the version number.
	jsr print_str	;
	lea d, ed_sver	; Print the sub version number.
	jsr print_str	;
	lea d, '\n'	; Print a newline.
	lda #'\n'	; Print a newline.
	jsr print_char	;
	lea d, made	; Print the "Created by" text.
	jsr print_str	;
	lea d, author	; Print the name of the author.
	jsr print_str	;
	lea d, '\n'	; Print a newline.
	lda #'\n'	; Print a newline.
	jsr print_char	;
	rts		; End of pnt_strt.


clr_cmd:
	and #0		; Reset A.
	tay		; Reset Y.
	lea s, CMDSIZE	; Set the clear count to CMDSIZE.
	lea d, (cmd_buf); Set the array to be cleared to the command buffer.
	jsr clr_arr	; Clear the command buffer.
	rts		; End of clr_cmd.


start:
	lda #0		; TODO: Update this for the Super VIA.
	sta status	; Clear the control register of the I/O adapter.
	tax		; Reset X.
	jsr clr_cmd	; Clear the command buffer.
	jsr update_ptr	; Get the screen buffer index.
	tay		; Save it in Y.
	and #0		; Reset the Accumulator.
	bra read	; Start reading the keyboard.

read:
	jsr getchar	; Get a character.
	jsr handle_char	; Send the character to the handler routine.
	beq parse	; The handled character was a newline, so start parsing.
	bra read	; Keep looping.

parse:
	and #0		; Reset A.
	tax		; Reset X.
	jsr subasm	; Call SuBAsm, and start parsing this line.
	bra start	; Go back to reading the keyboard.


getchar:
	and #0		; Reset A.
@loop:
	lda status	; Did we get a key?
	beq @loop	; No, so try again.
	lda kbd		; Yes, so get the typed character.
@end:
	rts		; End of getchar.


print_str:
	pha.q		; Preserve A.
	phb.q		; Preserve B.
	and #0		; Reset A.
	tba		; Reset B.
@loop:
	mov regb, #1	; Enable replace mode.
	and #0		; Reset A.
	mov b, (d)	; Are we at the end of the string?
	beq @end	; Yes, so we're done.
	jsr update_ptr	; No, so get the screen buffer index.
	tay		; Save it in Y.
	tba		; Get the character back.
	inc d		; Increment the string pointer.
	jsr print_char	; Print the character.
	bra @loop	; Keep looping.
@end:
	stz regb	; Enable insert mode.
	and #0		; Reset A.
	tab		; Reset B.
	pla.q		; Restore A.
	plb.q		; Restore B.
	rts		; End of print_str.


getbit:
	des			; Create the stack frame.
	add d, s		; Add the row position with the row offset position.
	lea s, (sp+1)		; Get the address of the bitmask.
	jsr bitpos		; Get the bit, and byte position.
	ins			; Cleanup the stack frame.
	mov a, (bitabl)+a	; Get the bit of the row position.
	and a, (s)		; Return the masked bit.
	rts			; End of getbit.


clrbit:
	pha.q			; Preserve A.
	des			; Create the stack frame.
	lea s, (sp+1)		; Get the address of the bitmask.
	jsr bitpos		; Get the bit, and byte position.
	ins			; Cleanup the stack frame.
	not (s)			; Invert the bitmask.
	and (bitabl)+a, (s)	; Set the bit of the current row number to zero.
	pla.q			; Restore A.
	rts			; End of clrbit.

setbit:
	pha.q			; Preserve A.
	phb.q			; Preserve B.
	mov b, s		; Save the bit.
	des			; Create the stack frame.
	lea s, (sp+1)		; Get the address of the bitmask.
	jsr bitpos		; Get the bit, and byte position.
	ins			; Cleanup the stack frame.
	cpb #1			; Is the bit set?
	bne @clear		; No, so clear the bit.
@set:
	or  (bitabl)+a, (s)	; Set the bit of the current row number to one.
	bra @end		; We are done.
@clear:
	not (s)			; Invert the bitmask.
	and (bitabl)+a, (s)	; Set the bit of the current row number to zero.
@end:
	plb.q			; Restore B.
	pla.q			; Restore A.
	rts			; End of setbit.

bitpos:
	mov a, d		; Preserve the row number.
	and d, #7		; Get the bit position.
	lsr #3			; Return the byte position.
	mov (s), (d+bits)	; Place the bitmask into the mask argument.
	rts			; End of bitpos.


handle_char:
	ldb #0		; Reset the B register.
	stb rege	; Set the temporary row position to zero, in case we get a newline.
	stb regb	; Enable insert mode.
	pha 		; Save the character.
	phy.w		; Save the cursor index.
	cmp #'\n'	; Was the character that was typed, a newline?
	bne @print	; No, so just print the character.
	jsr cmd_cpy	; Yes, so start copying the line to the command buffer.
@print:
	ply.w		; Get back the cursor index.
	pla 		; Get back the character.
	ldb rege	; Is the temporary row position non zero?
	bne @row	; Yes, so reset the row positon.
@print1:
	jsr print_char	; No, so print the character.
	lda rega	; Get the return value.
	cmp #'\n'	; Is the return value, a newline?
	beq @true	; Yes, so return true.
	bra @false	; No, so return false.
@row:
	ldb rege	; Get the temporary row position.
	cpb #maxrow	; Is temporary row position, at, or above the bottom of the screen?
	beq @row2	; Yes, so leave it as is.
	bcs @row1	; No, so set it to the bottom of the screen.
	bra @row2	; Yes, so leave it as is.
@row1:
	ldb #maxrow	; Set the row position to the bottom of the screen.
@row2:
	stb scr_row	; Set the row position.
	bra @print1	; Print the character.
@true:
	lda #0		; Return true.
	bra @end	; We are done.
@false:
	lda #1		; Return false.
@end:
	rts		; End of handle_char.


cmd_cpy:
	lda scr_row	; Get the row position.
	sta scr_trow	; Save it for later.
	lea d, (buffer)	; Get the screen buffer.
	mov s, y	; Get the cursor index.
;	jsr find_end	; Find the end of the line.
;	mov f, a	; Save the end of the line.
;	div #maxcol+1	; Get the ending line.
	jsr get_endrow	; Get the ending line.
;	inc step	;
	sub scr_str	; Offset the row position, back by the screen's starting point.
@start:
	sta scr_row	; Set the row position to the end of the line.
	sta rege	; Save it into the temporary row posiition.
	jsr findst	; Find the start of the line.
	lda scr_row	; Get the row position.
	add scr_str	; Add it with the screen's starting row.
	mul #maxcol+1	; Multiply it with the width of the screen, plus one.
	tay		; Place it into the index.
	ldx.w #0	; Reset the X register.
	ldb #0		; Make sure that set_ptr sets the first pointer.
	lda.q buffer	; Set the first pointer to the start of the screen buffer.
	jsr set_ptr	;
	inb		; Make sure that set_ptr sets the second pointer.
	lda.q cmd_buf	; Set the second pointer to the start of the command buffer.
	jsr set_ptr	;
	deb		; Set B back to zero.
	tba		; Set the accumulator to zero.
@loop:
	ldb #0		; Reset the B register.
	lda.q (ptr), y	; Get eight bytes from the current line.
@@loop:
	phy.w		; Save the screen index.
	txy		; Get the command buffer index.
	sta (ptr2), y	; Copy one byte from the screen buffer, to the command buffer.
	inx		; Increment the command buffer index.
	ply.w		; Get back the screen index.
	cpx.w #CMDSIZE	; Are we at the end of the command buffer?
	bcs @@end	; Yes, so we're done.
	iny		; No, so increment the screen index.
	inb		; Increment the byte count.
	lsr #8		; Shift in the next byte.
	stb regg	; Save the byte count.
	tab		; Save the string buffer.
	and #$FF	; Is this byte of the buffer, a null terminator?
	beq @@end	; Yes, so we're done.
	tba		; No so get back the string buffer.
	ldb regg	; Get back the byte count.
	cpb #7		; Did we shift in eight bytes?
	beq @loop	; Yes, so get eight more bytes.
	bra @@loop	; No, so keep shifting in more bytes.
@@end:
	ldb #0		; Reset B.
	phy.w		; Save the screen index.
	txy		; Get the command buffer index.
	stb (ptr2), y	; Terminate the command buffer.
	ply.w		; Get back the screen index.
@end:
	tab		; The B register is zero, so clear the Accumulator.
	rts		; End of cmd_cpy.


findst:
;	lda #0		; Reset A.
;	xor d, d	; Reset D.
;	xor s, s	; Reset S.
	mov d, scr_row	; Get the row position.
	mov s, scr_str	; Get the row offset.
@loop:
;	pha 		; Save the current line number.
	jsr getbit	; Is this the start of the line?
;	pla 		; Get the current line number back.
	beq @end	; Yes, so we're done.
	inc d		; No, so check the next physical line.
	dec scr_row	; Are we at the top of the screen?
	bpo @loop	; No, so keep looping.
	dec d		; Yes, so move back one line.
	inc scr_row	; Put the row postiion back to zero.
@end:
	cmp d, #0	; Update all the flags.
	rts		; End of findst.


;find_end:
;	mov a, s	; Set the loop counter.
;@loop:
;	inc		; Increment the loop counter.
;	cmp (d+a-1), #0	; Did we hit the null terminator?
;	bne @loop	; No, so keep looping.
;@end:
;	rts		; End of find_end2.


find_end:
	phb.q		; Preserve B.
	phx.q		; Preserve X.
	phy.q		; Preserve Y.
	mov a, s	; Set the loop counter.
	div #maxcol+1	; Get the row position.
	tay		; Save the row position.
	mov b, d	; Preserve the string pointer.
	mov x, s	; Preserve the cursor position.
	mov d, a	;
@loop:
	xor s, s	; Reset S.
	iny		; Increment the line.
	mov d, y	; Get the line.
	jsr getbit	; Is this the end of the line?
	bne @loop	; No, so keep looping.
@loop2_init:
	tya		; Get the ending row position.
	dec		; Decrement the row position.
	mul #maxcol+1	; Get the loop counter.
	cmp a, x	; Is the new loop counter less than the old loop counter?
	mcc a, x	; Set the loop counter to the old loop counter if so.
	mov d, b	; Restore the string pointer.
	mov s, x	; Restore the cursor position.
@loop2:
	inc		; Increment the loop counter.
	cmp (d+a-1), #0	; Did we hit the null terminator?
	bne @loop2	; No, so keep looping.
@end:
	ply.q		; Restore Y.
	plx.q		; Restore X.
	plb.q		; Restore B.
	rts		; End of find_end.


get_endrow:
	jsr find_end	; Find the end of the line.
	div #maxcol+1	; Get the ending row.
	rts		; End of get_endrow

;get_endrow2:
;	jsr find_end2	; Find the end of the line.
;	div #maxcol+1	; Get the ending row.
;	rts		; End of get_endrow


print_char:
	phb.q		; Preserve B.
	phx.q		; Preserve X.
	phe.q		; Preserve E.
	sta rega	; Preserve the character.
	ldb #2		; Make sure that set_ptr sets the third pointer.
	lda.q buffer	; Set the third pointer to the start of the screen buffer.
	jsr set_ptr	;
	deb		; Set B to one.
	tba		; Reset A.
;	inc step	;
	lda rega	; Get the character back.
	jsr get_ctrlidx	; Get the control code jump table index.
	lea ct_jtb	; Get the pointer to the jump table.
	mov.w e, (e+2*a); Get the address of the control code handler.
	deb		; Reset B.
	tba		; Reset A.
	jsr (e)		; Jump to the handler for that control code.
	ple.q		; Restore E.
	plx.q		; Restore X.
	plb.q		; Restore B.
	rts
printc:
	lda #0		; start trying to print a character.
	sta regd	;
	lda (ptr3), y	; Are we at the end of the string?
	beq @save	; Yes, so just print the character.
	lda regb	; No, but was the flag set?
	bne @save	; Yes, so don't shift the line.
;	sty.w scr_ptr	; No, so save the cursor index for later.
;	jsr fndend	; Find the end of the line.
	bra @shift	; Start shifting the line right.
@update:
	lda scr_col	; Save the current column position for later.
	sta scr_tcol	;
@update1:
	lea d, (buffer)	; Get the screen buffer.
	mov s, y	; Get the cursor index.
	jsr get_endrow	; Get the ending line.
	mov d, a	;
	mov s, scr_trow	; Get the current row position.
	lda scr_trow	; Get the current row position.
@update2:
	jsr rdrw_ln	; Redraw the line.
	lda scr_trow	; Get the real row position back.
	sta scr_row	;
	lda scr_tcol	; Get the real column position back.
	sta scr_col	;
	jsr update_pos	; Update the cursor's position.
	dec regd	;
	bra @save1	;
@shift:
;	ldy.w scr_ptr3	;
;	inc scr_ptr3	;
;	tyx		;
;	dey		;
;	ldb #1		;
;	stb regd	;
	lea d, (buffer)	; Get the screen buffer.
	mov.w s, scr_ptr; Get the cursor index.
	lea f, 1	; Set the shift length to one.
	lea c, 1	; Set the left flag to true.
	jsr shftln	;
	ldb #1		;
	stb regd	;
	lda rega	;
	sta (ptr3), y	; store typed character into the input buffer.
	lda scr_row	;
	sta scr_trow	;
	bra @update	;
@save:
	ldb regd	;
	bne @update	;
@save1:
	lda rega	;
	sta (ptr3), y	; store typed character into the input buffer.
@incr:
	inc scr_col	; Increment the cursor's x coordinate.
	inc.w scr_ptr	; Increment the screen index.
	iny		;
@wrapped:
	ldb #1		;
	stb regf	;
	ldb scr_col	;
	cpb #maxcol+1	;
	bcs @scrolled	;
@print:
	sta scr		; Echo typed character.
	ldb regf	;
	beq @wrap	;
	bra printc_end	;
@scrolled:
	ldb scr_row	;
	cpb #maxrow	;
	bcs @scroll	;
@wrapped2:
	ldb #0		;
	stb regf	;
	bra @print	;
@scroll:
	sta scr		; Echo typed character.
;	clc		;
	lda #1		;
	sta wrapped	;
	jsr scrl_down	;
@wrap:
	ldb #0
	stb scr_col	;
	ldb scr_row	;
	cpb #maxrow	;
	bcs @wrap2	;
@wrap1:
	inc scr_row	;
@wrap2:
;	phx.w		;
;	clc		;
;	lda scr_row	;
;	adc scr_str	;
;	tax		;
	mov d, scr_row	; Get the row position.
	add d, scr_str	; Add the row offset to the row position.
	lea s, 1	; Set the bit to one.
	jsr setbit	; Set the bit of that row.
;	plx.w		;
	jsr update_pos	;
printc_end:
	rts		;

nl:
	lda #0		; Reset A.
	ldb (ptr3), y	; Is this character not a null terminator?
	bne @scroll	; Yes, so don't overwrite it.
	sta (ptr3), y	; No, so overwrite it.
@scroll:
	sta scr_col	; Move the cursor to the start of the next line.
	lda scr_row	; Get the row position.
	cmp #maxrow	; Are we at the bottom of the screen?
	bcc @incr	; No, so move down one line.
	jsr scrl_down	; Yes, so scroll down one line.
	bra @end	; We are done.
@incr:
	inc scr_row	; Move the cursor down by one line.
	jsr update_pos	; Update the cursor's position.
@end:
	lda #'\n'	; Print the newline.
	sta rega	;
	rts		;


clr_scr:
	lda #maxrow	;
	sta scr_end	;
	stz scr_str	;
	tay		;
	lea s, LWSIZE	; Set the clear count to LWSIZE.
	lea d, (bitabl)	; Set the array to be cleared to the linewrap table.
	jsr clr_arr	; Clear the linewrap table.
	lea s, SCRSIZE	; Set the clear count to SCRSIZE.
	lea d, (buffer)	; Set the array to be cleared to the screen buffer.
	jsr clr_arr	; Clear the screen buffer.
;	lda.w #CMDSIZE	; Set the clear count to CMDSIZE.
;	lea (cmd_buf)	; Set the array to be cleared to the command buffer.
;	jsr clr_arr	; Clear the screen buffer.
	stz scr_col	;
	stz scr_row	;
	jsr update_pos	;
	lda #$C		;
	sta scr		;
	rts		;

en_step:
	lda step	;
	beq step_en	;
	rts		;
step_en:
	lda #1		;
	sta step	;
	rts		;

dis_step:
	lda step	;
	bne step_dis	;
	rts		;
step_dis:
	lda #0		;
	sta step	;
	rts		;


bs:
	lda scr_col	; Are we at the far left of the screen?
	beq @wrap	; Yes, so check for a wrapped line.
	bra back	; No, so add the backspace to the buffer.
@wrap:
	mov d, scr_row	; Get the row position.
	mov s, scr_str	; Get the row offset.
	jsr getbit	; Is this line, a wrapped line?
	bne @wrap1	; Yes, so check if the cursor is at the top.
	rts		; No, so we're done.
@wrap1:
	lda scr_row	; Are we at the top of the screen?
	beq @wrap2	; Yes, so check if the screen is at the top of the buffer.
	bra @wrap3	; No, so start clearing the wrap bit.
@wrap2:
	lda scr_str	; Are we at the top of the buffer?
	bne @scroll	; Yes, so scroll up.
	rts		; No, so we're done.
@scroll:
	jsr scrl_up	; Scroll up.
	inc scr_row	; Move down by one row.
@wrap3:
	lda scr_row	; Add the cursor's row position,
	add scr_str	; and the screen's starting row.
	tax		; Transfer that into X.
@wrap4:
	dec scr_row	; Move up by one row.
	ldb #maxcol+1	; Move the cursor to the absolute right of the screen.
	stb scr_col	;
	jsr update_pos	; Update the cursor's position.
back:
	ldb #0		; Reset B, and some flags.
	stb rege	;
	stb regf	;
	lda scr_row	; Save the current row position for later.
	sta scr_trow	;
	lea d, (buffer)	; Get the screen buffer.
	mov s, y	; Get the cursor index.
	jsr get_endrow	; Get the ending line.
	sta scr_row	; Set our row position to the end of the line.
@find_st:
	jsr findst	; Does this line take up more than one real line?
	beq @shift	; No, so skip updating any other lines.
	bcs @update	; Yes, so update the other lines.
	lda scr_trow	; Get the real row position back.
	sta scr_row	;
@shift:
	dey		; Decrement the buffer's offset.
	lda #0		; Place a null terminator
	sta (ptr3), y	; into the buffer.
	tyx		; Copy the current cursor index to X.
	iny		; Increment cursor index.
	ldb #0		; Set shifting direction to left.
	stb regd	;
	lea d, (buffer)	; Get the screen buffer.
	mov s, y	; Get the cursor index.
	lea f, 1	; Set the shift length to one.
	lea c, 0	; Set the left flag to false.
	jsr shftln	; Shift line back by one character.
	lda #$7F	; Print a backspace to the screen.
	sta scr		;
	lda rege	; Are we updating more than one line?
	beq @load	; No, so skip to the next step.
@find_end:
	lea d, (buffer)	; Get the screen buffer.
	mov s, y	; Get the cursor index.
	jsr get_endrow	; Yes, so Get the ending line.
	mov d, a	;
	mov s, scr_trow	; Get the current row position.
	lda scr_col	; Save the current column position for now.
	sta scr_tcol	;
	jsr rdrw_ln	; Start redrawing the line.
	lda scr_tcol	; Get the real column position back.
	sta scr_col	;
@load:
	lda scr_trow	; Get the real row position back.
	sta scr_row	;
	dec scr_col	; Move the cursor back by one column,
	jsr update_pos	; and update it's position.
	rts		; We are done.
@update:
	lda (ptr3), y	; Are we at the end of the line?
	beq @shift	; Yes, so skip redrawing.
	lda scr_trow	; No, so set the line to start redrawing, to the line that the cursor is on.
	inc rege	; Set the redraw flag to true.
	bra @shift	; Start shifting the line back.


;shftln:
;	pha.q			; Preserve A.
;	phb.q			; Preserve B.
;	and f, f		; Is the left flag not set?
;	beq @right		; Yes, so shift the line to the right.
;;	txa			; Get the end of the line.
;	jsr find_end		; Find the end of the line.
;	dec			; Decrement the source position.
;	bra @left		; No, so shift the line to the left.
;@minus:
;	and #0			; Set the source poition to 0.
;	mov (d), a		; Clear the character that is in the source.
;	bra @lend		; We are done.
;@left:
;	cmp s, a		; Is the cursor index, at, or below the source position?
;	beq @left1		; Yes, so keep looping.
;	bcs @lend		; No, so we're done.
;@left1:
;	cmp #0			; Is the source position less than 0?
;	bcc @minus		; Yes, so set the source position to zero.
;	mov (d+a+1), (d+a)	; No, so shift the current character to the left by one.
;	mov (d+a), #0		; Clear the current character.
;	dec			; Decrement the source position.
;	bra @left		; Keep looping.
;@right:
;	cmp (d+s), #0		; Is this character a null terminator?
;	beq @rend		; Yes, so we're done.
;	mov (d+s-1), (d+s)	; No, so shift the current character to the right by one.
;	mov (d+s), #0		; Clear the current character.
;	inc s			; Increment the source position.
;	bra @right		; Keep looping.
;@wrap:
;	mov d, a		; Get the ending line.
;	lea s, f		; Set the bit to the left flag.
;	jsr setbit		; Set the wrap bit of the ending line.
;	bra @end		; We are done.
;@lend:
;	lea s, (a+2)		; Add 2 to the source position.
;	jsr find_end		; Find the end of the line.
;	dec			; Decrement the end of line position.
;	div #maxcol+1		; Get the ending line.
;@lend2:
;	cmp scr_row		; Is the ending line greater than the starting line?
;	beq @end		; No, so we're done.
;	bcs @wrap		; Yes, so set the wrap bit.
;	bra @end		; No, so we're done.
;@rend:
;	lea f, 0		; Set the decrement offset to one.
;	jsr find_end		; Find the end of the line.
;	dec			; Decrement the end of line position.
;	div #maxcol+1		; Get the ending line.
;	cpb #0			; Is the remainder zero?
;	bne @end		; No, so we're done.
;@rend2:
;	cmp scr_row		; Is the ending line greater than the starting line?
;	beq @end		; No, so we're done.
;	bcs @wrap		; Yes, so clear the wrap bit.
;@end:
;	plb.q			; Restore B.
;	pla.q			; Restore A.
;	rts			; End of shftln.


;minmax:
;	psh.q d			; Preserve D.
;	psh.q s			; Preserve S.
;	mov d, e		; Get the shift length.
;	mov s, b		; Get the ending position.
;	jsr max			; Get the largest value.
;	mov f, a		; Save the largest value.
;	jsr min			; Get the smallest value.
;	pul.q s			; Restore S.
;	pul.q d			; Restore D.
;	rts			; End of minmax.


;shftln:
;	pha.q			; Preserve A.
;	phb.q			; Preserve B.
;	phx.q			; Preserve X.
;	phy.q			; Preserve Y.
;	phe.q			; Preserve E.
;	mov x, d		; Get the string pointer.
;	mov y, s		; Get the cursor position.
;	mov e, f		; Get the shift length.
;@find_end:
;	lea f, 1		; Set the decrement offset to the left flag.
;	jsr find_end		; Find the end of the line.
;	mov f, e		; Get the shift length.
;	tab			; Save the end position for later.
;	and #0			; Reset A.
;	dec			; Set our offset to -1.
;	and c, c		; Is the left flag set?
;	mne a, f		; Set our offset to the length argument if so.
;@copy:
;	add a, s		; Add the cursor position with the offset.
;	lea s, (d+s)		; Get the address of the string pointer, at the cursor position.
;	lea d, (d+a)		; Get the address of the string pointer, at the cursor position, plus the offset.
;	jsr minmax		; Get the minimum, and maximum values.
;@check_length:
;	cpe #2			; Is the shift length greater than one?
;	bcc @offset0		; No, so skip the subtraction below.
;	cmp f, y		; Yes, and is the end position greater than, or equal to the the cursor position?
;	bcc @offset		; No, so skip the subtraction below.
;	and c, c		; Yes, and is the left flag set?
;	beq @offset0		; No, so skip the subtraction below.
;@sub:
;	tya			; Set the offset to the cursor position.
;	bra @offset		; Subtract the offset.
;@offset0:
;	sub f, a		; Subtract the end position by the shift length.
;	bra @sub		; Subtract the cursor position.
;@offset:
;	sub f, a		; Subtract the offset.
;@copy2:
;	jsr memcpy		; Copy the string from the cursor, to the cursor plus the offset.
;@clear:
;	jsr minmax		; Get the minimum, and maximum values.
;	cmp #1			; Is the smallest value equal to one?
;	bne @clear2		; No, so skip incrementing the value.
;	inc			; Increment the smallest value.
;@clear2:
;	sub f, a		; Subtract the end position by the shift length.
;	mov d, y		; Get the cursor position.
;	and c, c		; Is the left flag set?
;	meq d, f		; Get the end position, minus the shift length if so.
;	lea d, (x+d)		; Get the address of the string pointer, at the offset.
;	xor s, s		; Reset S.
;	mov f, e		; Restore the shift length.
;	jsr memset		; Clear shift length bytes of the string, from the offset.
;@neg:
;	and c, c		; Is the left flag set?
;	bne @get_rows		; Yes, so don't negate the shift length.
;	neg f			; Negate the shift length.
;@get_rows:
;	mov x, b		; Save the end position.
;	lea a, (b+f)		; Add, or subtract the end position, by the shift length.
;	div #maxcol+1		; Get the new ending line.
;	mov e, a		; Save the ending line.
;	xor f, f		; Reset F.
;	and c, c		; Is the left flag set?
;	meq f, b		; Save the remainder of the ending line if not.
;	tya			; Get the cursor position.
;	div #maxcol+1		; Get the cursor line.
;	and c, c		; Is the left flag set?
;	meq a, e		; Set the starting line to the new ending line if not.
;	tay			; Save the starting line.
;	txa			; Get the end position.
;	div #maxcol+1		; Get the old ending line.
;	and c, c		; Is the left flag set?
;	mne a, e		; Set the ending line to the new ending line if so.
;	tab			; Save the ending line.
;	and c, c		; Is the left flag set?
;	bne @inc		; Yes, so increment the starting line.
;	cmp y, b		; No, but is the starting line less than the ending line?
;	bcs @loop		; No, so don't increment.
;	iny			; Yes, so increment the starting line.
;	bra @getbit		; Get the bit.
;@loop:
;	xor s, s		; Reset S.
;	cmp y, b		; Is the current line greater than the ending line?
;	beq @rem		; The current line is equal to the ending line, so check the remainder.
;	bcs @end		; Yes, so we're done.
;	bra @getbit		; No, so get the bit.
;@rem:
;	and f, f		; Is the remainder zero?
;	bne @end		; No, so we're done.
;@getbit:
;	mov d, y		; Get the current line.
;	jsr getbit		; Get the linewrap bit of that line.
;	cmp a, c		; Is the linewrap bit the opposite value of the left flag?
;	beq @inc		; No, so keep looping.
;@setbit:
;	mov d, y		; Get the current line.
;	mov s, c		; Get the left flag.
;	jsr setbit		; Set the linewrap bit to the left flag.
;@inc:
;	iny			; Increment the current line.
;	bra @loop		; Keep looping.
;@end:
;	ple.q			; Restore E.
;	ply.q			; Restore Y.
;	plx.q			; Restore X.
;	plb.q			; Restore B.
;	pla.q			; Restore A.
;	rts			; End of shftln.


shftln:
	pha.q			; Preserve A.
	phb.q			; Preserve B.
	phx.q			; Preserve X.
	phy.q			; Preserve Y.
	phe.q			; Preserve E.
	psh.q bp		; Preserve BP.
	mov x, d		; Get the string pointer.
	mov y, s		; Get the cursor position.
	mov e, f		; Get the shift length.
	and c, c		; Is the left flag set?
	bne @find_end		; Yes, so find the end of the line.
	cmp s, f		; No, but is the cursor position greater than, or equal to the shift length?
	bcc @end		; No, so we're done.
@find_end:
	jsr find_end		; Find the end of the line.
	sub a, c		; Decrement the old end position, if the left flag is set.
	tab			; Save the old end position for later.
	mov a, f		; Get the shift length.
	neg a			; Negate the shift length.
	and c, c		; Is the left flag set?
	mne a, f		; Set our offset to the shift length if so.
	lea bp, (b+a)		; Add the old end position, with the offset to get the new end position.
@copy:
	add a, y		; Add the cursor position with the offset.
	lea s, (x+y)		; Get the address of the string pointer, at the cursor position.
	lea d, (x+a)		; Get the address of the string pointer, at the cursor position, plus the offset.
	mov f, b		; Get the old end position.
	sub f, y		; Subtract the old end position, by the cursor position.
	jsr memcpy		; Copy the string from the cursor, to the cursor plus the offset.
@clear:
	tya			; Get the cursor position.
	and c, c		; Is the left flag set?
	meq a, bp		; Set our offset to the new end position if not.
	lea d, (x+a)		; Get the address of the string pointer, at the offset position.
	xor s, s		; Reset S.
	mov f, e		; Get the shift length.
	jsr memset		; Clear shift length bytes of the string, from the offset.
@get_rows:
	mov x, b		; Save the old end position.
	mov a, bp		; Get the new end position.
	div #maxcol+1		; Get the new ending line.
	mov e, a		; Save the ending line.
	mov r11, f		; Get the shift length.
	xor f, f		; Reset F.
	and c, c		; Is the left flag set?
	meq f, b		; Save the remainder of the ending line if not.
;	div #maxcol+1		; Get the line length.
;	dec			; Decrement the line length.
;	mov bp, a		; Save the line length.
	tya			; Get the cursor position.
	div #maxcol+1		; Get the cursor line.
	mov bp, a		; Save the cursor line.
	and c, c		; Is the left flag set?
	meq a, e		; Set the starting line to the new ending line if not.
	tay			; Save the starting line.
	txa			; Get the old end position.
	div #maxcol+1		; Get the old ending line.
	cmp bp, a		; Is the cursor line greater than, or equal to the old ending line?
	mcs a, bp		; Get the cursor line if so.
	cmp r11, #maxcol+1	; Is the shift length greater than, or equal to the max column count?
	adc #0			; Increment the starting line if so.
	and c, c		; Is the left flag set?
	mne a, e		; Set the ending line to the new ending line if so.
	tab			; Save the ending line.
	and c, c		; Is the left flag set?
	bne @inc		; Yes, so increment the starting line.
	cmp y, b		; No, but is the starting line less than the ending line?
	bcc @inc		; Yes, so increment the starting line.
@loop:
	xor s, s		; Reset S.
	cmp y, b		; Is the current line greater than the ending line?
	beq @rem		; The current line is equal to the ending line, so check the remainder.
	bcs @end		; Yes, so we're done.
	bra @getbit		; No, so get the bit.
@rem:
	and f, f		; Is the remainder zero?
	bne @end		; No, so we're done.
@getbit:
	mov d, y		; Get the current line.
	jsr getbit		; Get the linewrap bit of that line.
	cmp a, c		; Is the linewrap bit the opposite value of the left flag?
	beq @inc		; No, so keep looping.
@setbit:
	mov d, y		; Get the current line.
	mov s, c		; Get the left flag.
	jsr setbit		; Set the linewrap bit to the left flag.
@inc:
	iny			; Increment the current line.
	bra @loop		; Keep looping.
@end:
	pul.q bp		; Restore BP.
	ple.q			; Restore E.
	ply.q			; Restore Y.
	plx.q			; Restore X.
	plb.q			; Restore B.
	pla.q			; Restore A.
	rts			; End of shftln.


esc:
	lda status	; Get the next character.
	lda kbd		;
	cmp #'\e'	; Is this character an escape character?
	beq shftesc	; Yes, so check the other set of escape routines.
	lda status	; No, so wait for the next character.
	beq @end	; We have an error, so discard it, and go back to getting user input.
	lda kbd		; Get the escape code.
	sta regc	; Store the escape code, until we need it.
	lda #0		; Set the D pseudo register to zero.
	sta regd	;
	jsr isup	; Check if the user pressed up.
	lda regd	; Did the user press up?
	bne @end	; Yes, so we're done.
	jsr isdown	; No, so check if the user pressed down.
	lda regd	; Did the user press down?
	bne @end	; Yes, so we're done.
	lda #0		; No, so check if the user pressed left.
	jsr isleft	;
	lda regd	; Did the user press left?
	bne @end	; Yes, so we're done.
	jsr isright	; No, so check if the user pressed right.
@end:
	lda #0		; Clear the D pseudo register.
	sta regd	;
	rts		; We are done.

shftesc:
	lda status	; Skip the '['.
	lda kbd		;
	lda status	; Wait for the next character.
	beq @end	; We have an error, so discard it, and go back to getting user input.
	lda kbd		; Get the escape code.
	sta regc	; Store the escape code, until we need it.
	lda #0		; Use the D pseudo register as a skip flag.
	sta regd	;
	jsr isshftup	; Check if the user pressed shift+up.
	lda regd	; Was it successful?
	bne @end	; Yes, so we're done.
	jsr isshftdown	; No, so check if the user pressed shift+down.
@end:
	lda #0		; Clear the D pseudo register.
	sta regd	;
	rts		; We are done.


isup:
	lda regc	; Load the escape code into the accumulator.
	cmp #'A'	; Did the user press the up arrow key?
	bne @end	; No, so we're done.
	lda scr_row	; Yes, but is the cursor at the top of the screen?
	beq @scroll	; Yes, so check if we need to scroll.
@check2:
	lda regc	; No, so load the escape code back into the accumulator.
	cmp #'A'	; Did the user press the up arrow key?
	beq @up		; Yes, so move the cursor up.
	bra @end	; No, so we're done.
@up:
	dec scr_row	; Move the cursor up a line.
	jsr update_pos	; Update it's position.
	lda #1		; Tell the escape routine that we succeded.
	sta regd	;
	rts		; We are done.
@scroll:
	lda scr_str	; Are we at the top of the screen buffer?
	beq @end	; Yes, so we're done.
	jsr scrl_up	; No, so scroll up.
	lda #1		; Tell the escape routine that we were successful.
	sta regd	;
@end:
	rts		; End of isup.


isdown:
	lda regc	; Load the escape code into the accumulator.
	cmp #'B'	; Did the user press the down arrow key?
	bne @end	; No, so we're done.
	lda scr_row	; Yes, so start checking the y coordinate of the cursor.
	cmp #maxrow	; Is the cursor at the bottom of the screen?
	beq @scroll	; Yes, so scroll down.
	lda regc	; No, so load the escape code back into the accumulator.
	cmp #'B'	; Did the user press the down arrow key?
	beq @down	; Yes, so move the cursor down.
	bra @end	; No, so we're done.
@down:
	inc scr_row	; Move the cursor down a line.
	jsr update_pos	; Update it's position.
	lda #1		; Tell the escape routine that we succeded.
	sta regd	;
	rts		; We are done.
@scroll:
	lda scr_row	; Save the cursor's row number.
	sta scr_trow	;
	lda scr_col	; Save the cursor's column number.
	sta scr_tcol	;
	jsr scrl_down	; Scroll down.
	lda scr_trow	; Load the cursor's row number.
	sta scr_row	;
	lda scr_tcol	; Load the cursor's column number.
	sta scr_col	;
	lda #1		; Tell the escape routine that we were successful.
	sta regd	;
@end:
	rts		; End of isdown.


isright:
	lda regc	; Load the escape code into the accumulator.
	cmp #'C'	; Did the user press the right arrow key?
	bne @end2	; No, so we're done.
	lda scr_col	; Yes, so start checking the x coordinate of the cursor.
	cmp #maxcol	; Is the cursor at the far right of the screen?
	beq @wrap	; Yes, so check if this is a wrapped line.
	bra @right	; No, so move the cursor right, like normal.
@wrap:
	inc scr_row	; Move down a row.
	mov d, scr_row	; Get the row position.
	mov s, scr_str	; Get the row offset.
	jsr getbit	; Is the current line, a wrapped line?
	bne @incr	; Yes, so leave the cursor where it is.
	dec scr_row	; No, so move the cursor back up a row.
	bra @end2	; We are done.
@scroll:
	lda scr_str	; Are we at the top of the screen buffer?
	beq @end	; Yes, so we're done.
	lda #1		; No, so scroll down.
	sta wrapped	; Set the wrapped flag.
	jsr scrl_down	; Scroll down.
	bra @end	; We are done.
@incr:
	lda #0		; Set the cursor to the far left of the screen.
	sta scr_col	;
	lda scr_row	; Get the current row number.
	cmp #maxrow	; Are we at the bottom of the screen?
	beq @end1	; No, so we're done.
	bcs @scroll	; Yes, so check if we are scrolling down.
	bra @end1	; No, so we're done.
@right:
	inc scr_col	; Move the cursor right by one character.
	jsr update_pos	; Update it's position.
	rts		; End of isright.
@end:
	dec scr_row	; Move back up a row.
@end1:
	jsr update_pos	; Update the cursor position.
@end2:
	lda #0		; Unset the wrapped flag.
	sta wrapped	;
	rts		; End of isright.


isleft:
	lda regc	; Load the escape code into the accumulator.
	cmp #'C'	; Did the user press right?
	beq @end1	; Yes, so we're done
	lda scr_col	; No, but is the cursor at the far left of the screen?
	beq @wrap	; Yes, so start checking if this is a wrapped line.
	lda regc	; No, so load the escape code back into the accumulator.
	cmp #'D'	; Did the user press the left arrow key?
	beq @left	; Yes, so move the cursor left.
	bra @end1	; No, so we're done.
@wrap:
	mov d, scr_row	; Get the row position.
	mov s, scr_str	; Get the row offset.
	jsr getbit	; Is the current line, a wrapped line?
	bne @decr	; Yes, so wrap back up a line.
	bra @end1	; No, so we're done.
@decr:
	lda scr_row	; Is the cursor at the top of the screen?
	beq @@decr	; Yes, so don't move up a line.
	lda #1		; No, so set the wrapped flag.
	sta wrapped	;
	dec scr_row	; Move the cursor up one line.
@@decr:
	lda #maxcol	; Move the Cursor to the far right of the screen.
	sta scr_col	;
	lda #1		; Tell the escape routine that we were successful.
	sta regd	;
	lda scr_row	; Are we at the top of the screen?
	beq @scroll	; Yes, so check if we need to scroll.
	bra @end	; No, so we're done.
@scroll:
	lda wrapped	; Was the wrapped flag set somewhere else?
	bne @end	; Yes so we're done.
	lda scr_str	; No, but are we actually at the top of the screen buffer?
	beq @end1	; Yes, so we're done.
	jsr scrl_up	; No, so scroll up.
	bra @end1	; We are done.
@left:
	dec scr_col	; Move the cursor left a character.
	jsr update_pos	; Update it's position.
	lda #1		; Tell the escape routine that we succeded.
	sta regd	;
	rts		; We are done
@end:
	jsr update_pos	; Update the cursor position.
@end1:
	lda #0		; Unset the wrapped flag.
	sta wrapped	;
	rts		; End of isleft.


isshftup:
	lda regc	; Load the escape code back into the accumulator.
	cmp #'A'	; Did the user press the up arrow key?
	bne @end	;
	lda #1		;
	sta regd	;
	lda scr_str	;
	beq @end	;
@shftup:
	jsr scrl_up	;
	lda #1		;
	sta regd	;
@end:
	rts		;


isshftdown:
	lda regc	; Load the escape code back into the accumulator.
	cmp #'B'	; Did the user press the down arrow key?
	bne @end	;
	lda #1		;
	sta regd	;
	lda scr_end	;
	cmp #71		;
	bcs @end	;
@shftdown:
	jsr scrl_down	;
	lda #1		;
	sta regd	;
@end:
	rts		;


update_ptr:
	lda scr_row	; Add the cursor's line number,
	add scr_str	; with the starting line number to get the absolute line number.
	mul #maxcol+1	; Multiply the line number by the screen's max column count, plus 1.
	add scr_col	; Add the cursor's column number to get the screen index.
	sta.w scr_ptr	; Save the screen index.
;	cmp.w #$2000	; Is the index greater than, or equal to the end of the screen buffer?
;	bcc @end	; No, so we're done.
;@wrap:
;	and #0		; Reset the screen's starting line.
;	sta scr_str	;
;	sta regf	; Setup the starting line for rdrw_ln.
;	lda #maxrow	; Reset the screen's ending line.
;	sta scr_end	;
;	sta rege	; Setup the ending line for rdrw_ln.
;	jsr rdrw_ln	; Redraw the entire screen.
;	bra update_ptr	; Get the screen index.
@end:
	rts		; End of update_ptr.


update_pos:
	phb.q		; Preserve B.
	and #0		; Reset A.
	tab		; Reset B.
	ldb #1		; Set the F pseudo register to one, to fix some bugs.
	stb regf	;
	jsr update_ptr	; Update the screen buffer index.
	tay		; Place the index into the Y register.
	tba		; Reset A.
	mov scr, #'\e'	; Print an escape character to the screen.
	mov scr, #'['	; Print '[' to the screen, and start the escape sequence.
	jsr getrow	; Start printing the row number to the screen.
	mov scr, #';'	; Print ';' to the screen.
	jsr getcol	; Start printing the column number to the screen.
	mov scr, #'H'	; Print 'H' to the screen.
	plb.q		; Restore B.
	rts		; End of update_pos.

getrow:
	lda scr_row	; Get the cursor's y coordinate.
	bra bcd		; Convert it to BCD.
getcol:
	lda scr_col	; Get the cursor's x coordinate.
bcd:
	inc		; Add one to A.
	div #10		; Divide A by 10.
	ora #'0'	; Convert it to ascii, and
	sta scr		; print to the screen.
	tba		; Get the remainder.
	ora #'0'	; Convert it to ascii, and
	sta scr		; print to the screen.
	rts		; End of bcd.

scrl_down:
	inc scr_str	; Increment the starting line of the screen.
	inc scr_end	; Increment the ending line of the screen.
	mov scr, #'\e'	; Print an escape character to the screen.
	mov scr, #'['	; Print '[' to the screen, and start the escape sequence.
	mov scr, #'T'	; Print 'T' to the screen, and end the escape sequence.
	lda scr_row	; Get the cursor's line number.
	pha 		; Save it in the stack.
	lda wrapped	; Was the wrapped flag set?
	beq @save	; Yes, so save the cursor position.
@redraw:
	lea d, (buffer)	; Get the screen buffer.
	jsr rdrw_row	; No, so redraw this row.
	lda wrapped	; Was the wrapped flag set?
	beq @load	; Yes, so load the previous cursor position back.
	bra @end	; No, so we're done.
@save:
	lda scr_col	; Get the cursor's column number.
	pha 		; Save it in the stack.
	bra @redraw	; Start redrawing the current row.
@load:
	pla 		; Get the cursor's previous column number back.
	sta scr_col	;
@end:
	pla 		; Get the cursor's previous line number back.
	sta scr_row	;
	jsr update_pos	; Update the cursor's position.
	lda #0		; Clear the wrapped flag.
	sta wrapped	;
@end1:
	rts		; End of scrl_down.

scrl_up:
	dec scr_str	;
	dec scr_end	;
	mov scr, #'\e'	; Print an escape character to the screen.
	mov scr, #'['	; Print '[' to the screen, and start the escape sequence.
	mov scr, #'S'	; Print 'S' to the screen, and end the escape sequence.
	lda scr_row	;
	pha 		;
	lda scr_col	;
	pha 		;
	lda #0		;
	sta scr_row	;
	lea d, (buffer)	; Get the screen buffer.
	jsr rdrw_row	;
	pla 		;
	sta scr_col	;
	pla 		;
	sta scr_row	;
	jsr update_pos	;
@end:
	rts		;


rdrw_row:
	pha.q		; Preserve A.
	phb.q		; Preserve B.
	stz scr_col	; Reset the column position.
	jsr update_pos	; Update the cursor position.
	xor b, b	; Reset B.
	tya		; Get the screen index.
	tab		;
	add b, #maxcol+1; Get the end of the row plus one.
@loop:
	cmp (d+a), #0	; Is this a null terminator?
	mne scr, (d+a)	; No, so print the character.
	meq scr, #' '	; Yes, so print a space.
	inc		; Increment the screen index.
	cmp b		; Is the column position at, or above the maximum column count?
	bcc @loop	; No, so keep looping.
@end:
	stz scr_col	; Reset the column position.
	jsr update_pos	; Update the cursor position.
	plb.q		; Restore B.
	pla.q		; Restore A.
	rts		; End of rdrw_row.


rdrw_ln:
	pha.q		; Preserve A.
	psh scr_row	; Preserve the row position.
	psh scr_col	; Preserve the column position.
	mov scr_row, s	; Set the row position to the starting position.
	jsr update_pos	; Update the cursor position.
	mov a, d	; Get the ending position.
	lea d, (buffer)	; Get the address of the screen buffer.
@loop:
	cmp scr_row, a	; Is the row position at, or below the ending position?
	beq @redraw	; Yes, so redraw the row.
	bcs @end	; No, so we're done.
@redraw:
	jsr rdrw_row	; Redraw the line.
@incr:
	inc scr_row	; Increment the row position.
	bra @loop	; Keep looping
@end:
	pul scr_col	; Restore the column position.
	pul scr_row	; Restore the row position.
	jsr update_pos	; Update the cursor position.
	pla.q 		; Restore A.
	rts		; End of rdrw_ln.


set_ptr:
	cpb #1		; Are we setting the second pointer?
	beq @ptr2	; Yes, so start setting it.
	cpb #2		; No, but are we setting the third pointer?
	beq @ptr3	; Yes, so start setting it.
@ptr1:
	stb.q ptr	; Reset the first pointer.
	sta.q ptr	; No, so set the first pointer.
	bra @end	; We are done.
@ptr2:
	stb.q ptr2	; Reset the second pointer.
	sta.q ptr2	; Set the second pointer.
	bra @end	; We are done.
@ptr3:
	stb.q ptr3	; Reset the third pointer.
	sta.q ptr3	; Set the third pointer.
@end:
	rts		; End of set_ptr.