From ca5f89b8f043b180c26ef2494cab52121ba97328 Mon Sep 17 00:00:00 2001
From: mrb0nk500 <b0nk@b0nk.xyz>
Date: Wed, 18 Dec 2019 17:44:07 -0500
Subject: Start work on SuBAsm.

Also added support for moving the cursor arround.
---
 programs/subasm.s | 239 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 239 insertions(+)
 create mode 100644 programs/subasm.s

(limited to 'programs')

diff --git a/programs/subasm.s b/programs/subasm.s
new file mode 100644
index 0000000..fe02794
--- /dev/null
+++ b/programs/subasm.s
@@ -0,0 +1,239 @@
+; SuBAsm
+; The Sux Bootstrapped Assembler.
+;
+; by mr b0nk 500 <b0nk@b0nk.xyz>
+
+; Variables
+.org $1000
+prg_name:
+	.byte "SuBAsm"
+ver_txt:
+	.byte ", version "
+ver_num:
+	.byte "0.1"
+x:
+	.word $0
+y:
+	.word $0
+
+str_buf:
+
+; Input buffer.
+.org $2000
+buf:
+
+; Control Register.
+.org $C000
+ctrl_reg:
+
+; Screen.
+.org $C001
+scr:
+
+; Keyboard.
+.org $C002
+kbd:
+
+; Main program.
+.org $0
+reset:
+	cps
+	ldx.w #$FFFF
+	txs
+	ldy #$0
+	jsr clr_buf
+	ldx.w #$0	; Reset x.
+	ldy #$0		; Reset y.
+	jmp print_title
+
+read:
+	lda ctrl_reg	; Is the keyboard ready?
+	beq read	; Loop until the keyboard is ready.
+	lda #$0		; Start resetting the control register.
+	sta ctrl_reg	; Reset the control register.
+	jmp getchar	; We got a key.
+
+rset_x:
+
+	ldx #$0		; Reset x.
+	stx.w x
+	rts
+
+print_title:
+	lda prg_name, x
+	beq print_ver	; Did we find a null terminator?
+	sta		; Print character.
+	inx		; Increment offset.
+	inc x
+	jmp print_title	; Keep printing more characters.
+
+print_ver
+	jsr rset_x
+	lda ver_txt, x
+	beq print_num	; Did we find a null terminator?
+	sta scr		; Print character.
+	inx		; Increment offset.
+	jmp print_ver	; Keep printing more characters.
+
+print_num:
+	lda ver_num, x
+	beq getline	; Did we find a null terminator?
+	sta scr		; Print character.
+	inx		; Increment offset.
+	jmp print_num	; Keep printing more characters.
+getline:
+	lda #$A
+	sta scr		; Print newline
+	inc y
+	jsr rset_x
+	jmp read
+
+getchar:
+	lda kbd		; Get typed character.
+	cmp #$1B	; Did the user type an escape?
+	beq esc		; Yes, so start getting the escape code.
+	cmp #$A		; Did the user type a newline?
+	beq nl		; Yes, so start parsing the input.
+	cmp #$8		; Did the user type a backspace?
+	beq bs		; Yes, so start checking the buffer.
+	jsr echo	; Print character to screen.
+
+store_char:
+	sta buf, y	; Store typed character into the input buffer.
+	iny		; Increment buffer offset.
+	jmp read	; Get another character.
+
+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.
+	lda kbd		; Get the escape code.
+	cmp #$41	; Did the user press the up arrow?
+	beq up		; Yes, so move the cursor up.
+	cmp #$42	; Did the user press the down arrow?
+	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?
+	beq right	; Yes, so move the cursor right.
+
+up:
+	lda #$1B
+	sta scr
+	lda #$5B
+	sta scr
+	lda #$41
+	sta scr
+	jmp read
+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
+right:
+	lda #$1B
+	sta scr
+	lda #$5B
+	sta scr
+	lda #$44
+	sta scr
+	jmp read
+
+
+
+nl:
+	sta scr		; Print newline.
+	lda #$0		; Put a null terminator, in place of the newline.
+	sta buf, y	; Place it into the input buffer.
+	ldy.w #$0	; Reset y, to parse the input.
+	jmp parse
+
+back:
+	jsr echo	; Print backspace.
+	lda #$0		; Put a null terminator, in place of the backspace.
+	sta buf, y	; Place it into the input buffer.
+	dey		; Decrement buffer offset.
+	jmp read	; Get next character.
+
+bs:
+	cpy #$0		; Are we at the start of the buffer?
+	beq read	; We are, so do not store the backspace into the buffer.
+	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, '
+	iny		; Increment offset.
+	jmp result	; Keep printing.
+
+rset_y:
+	ldy.w #$0
+	jmp print_buf	; Print the input buffer.
+
+print_buf:
+	lda buf, y	; Get a character from the input buffer.
+	beq fin		; Are we done with printing the buffer?
+	sta scr		; Print said character.
+	iny
+	jmp print_buf	; Keep printing the buffer.
+
+spin:
+	nop
+	nop
+	nop
+	jmp spin
+
+clr_buf:
+	lda #$0
+	cpy.w #$1000
+	beq clr_end
+	sta buf, y
+	iny
+	jmp clr_buf
+clr_sbuf:
+	lda #$0
+	cpy.w #$40
+	beq clr_end
+	sta str_buf, y
+	iny
+	jmp clr_sbuf
+
+clr_end:
+	rts
+
+echo:
+	sta scr		; Echo typed character.
+	rts		; Return.
+
+.org $FFC0
+.qword reset
+
+.org $FF50
+.qword spin
+.qword spin
+.qword spin
+.qword spin
+.qword spin
+.qword spin
+.qword spin
+
+.org $FFA0
+.qword irq_routine
+;.org $0
+;viewmem
+;.org $100
+;viewmem
+;q
+done
-- 
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