Added support for Indirect addressing modes, and allow

for use of the B register as an operand, for ALU based
instructions.

This allows for both low code size, and high
performance.
This means we can save upto 9 bytes, by just using
the B register for ALU operations, rather than using a
memory address.
The indirect addressing modes, give Sux the abillity
to now use pointers.

Hope you guys have a Merry Christmas!
From mr b0nk 500 <b0nk@b0nk.xyz>

1 files changed, 187 insertions, 45 deletions

diff --git a/programs/subasm.s b/programs/subasm.s
index 46effce..ddb7ba2 100644
--- a/programs/subasm.s
+++ b/programs/subasm.s
@@ -11,9 +11,18 @@ ver_txt:
 	.byte ", version "
 ver_num:
 	.byte "0.1"
-x:
+
+scr_row:
+	.byte $0
+scr_col:
+	.byte $0
+a:
+	.word $0
+b:
+	.word $0
+c:
 	.word $0
-y:
+d:
 	.word $0
 
 str_buf:
@@ -109,64 +118,137 @@ store_char:
 esc:
 	lda ctrl_reg	; Skip the '['.
 	lda ctrl_reg	; Get the next character.
-	beq read	; We have an error, so discard it, and read the next character.
+	beq read	; We have an error, so discard it, and go back to getting user input.
 	lda kbd		; Get the escape code.
-	cmp #$41	; Did the user press the up arrow?
+	sta c		; Store the escape code, until we need it.
+	jsr isup	; Check if the user pressed up.
+	lda d
+	cmp #$0
+	bne esc_end
+	jsr isdown	; Check if the user pressed down.
+	lda d
+	cmp #$0
+	bne esc_end
+	lda #$0
+	jsr isleft	; Check if the user pressed left.
+	lda d
+	cmp #$0
+	bne esc_end
+	jsr isright	; Check if the user pressed right.
+esc_end:
+	lda #$0
+	sta d
+	jmp rset_a	; Go back to getting user input.
+
+isup:
+	lda scr_row	; Is the cursor at the top of the screen?
+	beq isup_done	; Yes, so return.
+	lda c		; No, so load the escape code back into the accumulator.
+	cmp #$41	; Did the user press the up arrow key?
 	beq up		; Yes, so move the cursor up.
-	cmp #$42	; Did the user press the down arrow?
+isup_done:
+	rts		; End of isup.
+
+isdown:
+	lda scr_row	; Start checking the y coordinate of the cursor.
+	cmp #$17	; Is the cursor at the bottom of the screen?
+	beq isdown_done	; Yes, so return.
+	lda c		; No, so load the escape code back into the accumulator.
+	cmp #$42	; Did the user press the down arrow key?
 	beq down	; Yes, so move the cursor down.
-	cmp #$43	; Did the user press the left arrow?
-	beq left	; Yes, so move the cursor left.
-	cmp #$44	; Did the user press the right arrow?
+isdown_done:
+	rts		; End of isdown.
+
+isright:
+	lda scr_col	; Start checking the x coordinate of the cursor.
+	cmp #$4F	; Is the cursor at the far right of the screen?
+	beq isright_end	; Yes, so return.
+	lda c		; No, so load the escape code back into the accumulator.
+	cmp #$43	; Did the user press the right arrow key?
 	beq right	; Yes, so move the cursor right.
+isright_end:
+	rts		; End of isright.
+
+isleft:
+	lda scr_col	; Is the cursor at the far left of the screen?
+	beq isleft_done	; Yes, so return.
+	lda c		; No, so load the escape code back into the accumulator.
+	cmp #$44	; Did the user press the left arrow key?
+	beq left	; Yes, so move the cursor left.
+isleft_done:
+	rts		; End of isleft.
 
 up:
-	lda #$1B
-	sta scr
-	lda #$5B
-	sta scr
-	lda #$41
-	sta scr
-	jmp read
+	dec scr_row
+	jsr update_pos
+	lda #$1
+	sta d
+	jmp isup_done
 down:
-	lda #$1B
-	sta scr
-	lda #$5B
-	sta scr
-	lda #$42
-	sta scr
-	jmp read
-left:
-	lda #$1B
-	sta scr
-	lda #$5B
-	sta scr
-	lda #$43
-	sta scr
-	jmp read
+	inc scr_row
+	jsr update_pos
+	lda #$1
+	sta d
+	jmp isdown_done
 right:
-	lda #$1B
-	sta scr
-	lda #$5B
-	sta scr
-	lda #$44
-	sta scr
-	jmp read
+	inc scr_col
+	jsr update_pos
+	jmp isright_end
+left:
+	dec scr_col
+	jsr update_pos
+	lda #$1
+	sta d
+	jmp isleft_done
+
+update_pos:
+	lda #$1B	; Print an escape character
+	sta scr		; to the screen.
+	lda #$5B	; Print '['
+	sta scr		; to the screen, and start the escape sequence.
+	jsr getrow	; Start printing the row number to the screen.
+	jsr getcol	; Start printing the column number to the screen.
+	lda #$48	; Print 'H'
+	sta scr		; to the screen.
+	rts		; End of update_pos.
+getrow:
+	lda scr_row	; Get the cursor's y coordinate.
+	div #$A		; Divide A by 10.
+	adc #$30	; Convert it to ascii, and
+	sta scr		; print to the screen.
+	tba		; Get the remainder.
+	adc #$30	; Convert it to ascii, and
+	sta scr		; print to the screen.
+	rts		; End of getrow.
+getcol:
+	lda #$3B	; Print ';'
+	sta scr		; to the screen.
+	lda scr_col	; Get the cursor's x coordinate.
+	div #$A		; Divide A by 10.
+	adc #$30	; Convert it to ascii, and
+	sta scr		; print to the screen.
+	tba		; Get the remainder.
+	adc #$30	; Convert it to ascii, and
+	sta scr		; print to the screen.
+	rts		; End of getrow.
 
 
 
 nl:
 	sta scr		; Print newline.
+	inc scr_row	; Move the cursor down one line.
 	lda #$0		; Put a null terminator, in place of the newline.
-	sta buf, y	; Place it into the input buffer.
+	sta scr_col	; Move the cursor back to column 0.
+	sta str_buf, y	; Place it into the input buffer.
 	ldy.w #$0	; Reset y, to parse the input.
-	jmp parse
+	jsr parse	; Start parsing input.
 
 back:
-	jsr echo	; Print backspace.
+	sta scr		; Print backspace.
 	lda #$0		; Put a null terminator, in place of the backspace.
-	sta buf, y	; Place it into the input buffer.
+	sta str_buf, y	; Place it into the input buffer.
 	dey		; Decrement buffer offset.
+	dec scr_col
 	jmp read	; Get next character.
 
 bs:
@@ -175,11 +257,55 @@ bs:
 	jmp back	; We are not, so add the backspace to the buffer.
 
 parse:
-	lda buf, y
-	beq clr_buf	; Reset y, if we hit the null terminator.
-	sta scr		; Print 'You have typed, '
+	jmp parse	; Keep printing.
+	jsr clr_sbuf
+	rts
+
+forg:
 	iny		; Increment offset.
-	jmp result	; Keep printing.
+	lda str_buf, y
+	jsr iswhite
+	bcs forg	; Reset y, if we hit the null terminator.
+	cmp #$2E	; Is this character a '.'?
+	bne forg_exit	; No, so return.
+	sty org		; Yes, so store the origin.
+forg_end:
+	iny		; Increment offset.
+	lda str_buf, y
+	jsr istoken
+	bcs forg_end
+	dey
+	sty scr_col
+forg_exit:
+	rts		; End of forg.
+
+istoken:
+	cmp #$20	; Is this character a space?
+	beq istoken_f	; Yes, so return false.
+	cmp #$09	; Is this character a tab?
+	beq istoken_f	; Yes, so return false.
+	cmp #$A		; Is this character a newline?
+	beq istoken_f	; Yes, so return false.
+	cmp #$3B	; Is this character a ';'?
+	beq istoken_f	; Yes, so return false.
+	cmp #$0		; Is this character a null terminator?
+	beq istoken_f	; Yes, so return false.
+	sec		; Return true.
+	rts		; End of istoken.
+istoken_f
+	clc		; Return false.
+	rts		; End of istoken_f.
+
+iswhite:
+	cmp #$20	; Is this character a space?
+	beq iswhite_t	; Yes, so return true.
+	cmp #$09	; Is this character a tab?
+	beq iswhite_t	; Yes, so return true.
+	clc		; No, so return false.
+	rts		; End of iswhite.
+iswhite_t:
+	sec		; Return true.
+	rts		; End of iswhite_t.
 
 rset_y:
 	ldy.w #$0
@@ -217,7 +343,23 @@ clr_end:
 	rts
 
 echo:
+	sta a
+	ldx scr_col
+	cpx #$4F
+	bne echo_print
+	cmp #$A
+	beq linewrap
+linewrap:
+	inc scr_row
+	ldx #$0
+	stx scr_col
+	jsr update_pos
+echo_print:
+	lda a
 	sta scr		; Echo typed character.
+	inc scr_col	; Increment the cursor's x coordinate.
+	sta str_buf, y	; Store typed character into the input buffer.
+	iny		; Increment the buffer offset.
 	rts		; Return.
 
 .org $FFC0