From 73722a2c025b49521fb0c0fd0decae4c19fd8388 Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Thu, 23 Sep 2021 23:43:25 -0400
Subject: [PATCH] enable cursor, some fixes

---
 apple2gs.equ.S | 22 ++++++++++++++++++++++
 vt100.main.S   | 22 +++++++++++++++-------
 vt100.screen.S | 42 ++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 77 insertions(+), 9 deletions(-)
 create mode 100644 apple2gs.equ.S

diff --git a/apple2gs.equ.S b/apple2gs.equ.S
new file mode 100644
index 0000000..842fabe
--- /dev/null
+++ b/apple2gs.equ.S
@@ -0,0 +1,22 @@
+SET80VID	equ $c00d
+SETALTCHAR	equ $c00f
+TXTSET		equ $c051
+KEYMOD		equ $c025
+KEYSTROBE	equ $c010
+KBD		equ $c000
+VGCINT		equ $c023
+SCANINT		equ $c032
+
+
+* modem port / printer port
+
+SCCBREG		equ $c038
+SCCAREG		equ $c039
+SCCBDATA	equ $c03a
+SCCADATA	equ $c03b
+
+* interrupt vectors.  JMP ABSLONG.
+IRQ1SEC		equ $e10054
+IRQQTR		equ $e10038
+IRQVBL		equ $e10030
+IRQSND		equ $e1002c
diff --git a/vt100.main.S b/vt100.main.S
index 9a3fb31..557b25f 100644
--- a/vt100.main.S
+++ b/vt100.main.S
@@ -6,21 +6,16 @@
 
 	mx %11
 	use vt.equ
+	use apple2gs.equ
 	use debug
 
 	ext scroll_down
 	ext recalc_cursor,recalc_cursor_x,recalc_cursor_y
 	ext write_modem,read_modem,init_modem,keypress
-	ext disable_cursor,enable_cursor
+	ext disable_cursor,enable_cursor,cursor_vector
 	ext erase_screen
 	ext init_tabs
 
-SET80VID	equ $c00d
-SETALTCHAR	equ $c00f
-TXTSET		equ $c051
-VGCINT		equ $c023
-SCANINT		equ $c032
-
 main	debug main
 
 	clc
@@ -71,6 +66,19 @@ init
 	lda #"  " ; 16-bit
 	sta erase_char
 
+
+
+	lda #$0080
+	sta cursor_state
+	sei
+	lda cursor_vector
+	stal IRQ1SEC
+	lda cursor_vector+2
+	stal IRQ1SEC+2
+	cli
+
+	lda #0 ; clear high byte
+
 	sep #$30
 
 	lda #"_"
diff --git a/vt100.screen.S b/vt100.screen.S
index 1b91168..80f0392 100644
--- a/vt100.screen.S
+++ b/vt100.screen.S
@@ -5,6 +5,7 @@
 	xc
 	xc
 	use vt.equ
+	use apple2gs.equ
 
 	mx %11
 
@@ -76,8 +77,10 @@ enable_cursor ent
 	bvc :80
 
 * option for inverted cursor?
-	lda cursor_char
 	ldy cursor_offset
+	lda [cursor_base],y
+	sta cursor_saved_char
+	lda cursor_char
 	sta [cursor_base],y
 
 :80	lda #$80
@@ -86,6 +89,41 @@ enable_cursor ent
 :rts	plp
 	rts
 
+
+cursor_vector	ent
+	jml cursor_int
+
+cursor_int
+* cursor interrupt - blink the cursor.
+
+	mx %11
+
+	ldy cursor_offset
+
+	lda cursor_state
+	bmi :rts
+	eor #$40
+	sta cursor_state
+	beq :off
+:on
+	lda [cursor_base],y
+	sta cursor_saved_char
+	lda cursor_char
+	sta [cursor_base],y
+
+	bra :rts
+
+:off
+	lda cursor_saved_char
+	sta [cursor_base],y
+
+:rts	stz SCANINT ; reset 1-sec interrupt
+	clc
+	rtl
+
+
+
+
 recalc_cursor ent
 * recalculate the cursor pointer after x/y changed
 * assumes cursor is off so no saving/restoring the cursor char.
@@ -190,7 +228,7 @@ draw_char ent
 
 :normal	ora #$80
 :draw
-
+*	sta cursor_saved_char
 
 * with DECAWM, x = 79, will CR LF (with scroll) before drawing character.