Initial work on silly Genesis based menu

1 files changed, 211 insertions, 0 deletions

diff --git a/menu.s68 b/menu.s68
new file mode 100644
index 0000000..3f6a769
--- /dev/null
+++ b/menu.s68
@@ -0,0 +1,211 @@
+	dc.l $0, start
+	dc.l empty_handler
+	dc.l empty_handler
+	;$10
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$20
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$30
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$40
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$50
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$60
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$70
+	dc.l int_4
+	dc.l empty_handler
+	dc.l int_6
+	dc.l empty_handler
+	;$80
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$90
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$A0
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$B0
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$C0
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$D0
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$E0
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	;$F0
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.l empty_handler
+	dc.b "SEGA"
+empty_handler:
+int_6:
+	rte
+int_4:
+	rte
+	
+	rsset $FFFF8000
+x_pos    rs.w 1
+base_cmd rs.l 1
+
+start:
+	lea $C00000, a0
+	lea $C00004, a1
+	move.w #$8104, (a1) ;Mode 5, everything turned off
+	move.w #$8004, (a1)
+	move.w #$8220, (a1) ;Scroll a table $8000
+	move.w #$8405, (a1) ;Scroll b table $A000
+	move.w #$8560, (a1) ;SAT table $C000
+	move.w #$8700, (a1) ;backdrop color 0
+	move.w #$8B00, (a1) ;full screen scroll
+	move.w #$8C87, (a1) ;40 cell mode, double-res interlace
+	move.w #$8D00, (a1) ;hscroll table at 0
+	move.w #$8F02, (a1) ;autoinc 2
+	move.w #$9001, (a1) ;64x32 scroll size
+	move.l #$C0000000, (a1)
+	move.w #$000, (a0)
+	move.w #$EEE, (a0)
+
+	;init scroll table
+	move.l #$40000000, (a1)
+	move.w #0, (a0)
+	move.w #4, (a0)
+
+	;load tiles
+	move.l #$48000000, (a1)
+	lea font(pc), a2
+	move.w #((fontend-font)/4 - 1), d0
+tloop:
+	move.l (a2)+, (a0)
+	dbra d0, tloop
+
+
+
+	;clear name table
+	move.l #$40000002, (a1)
+	moveq #32, d0
+	move.w #(64*64-1), d1
+ploop:
+	move.w d0, (a0)
+	dbra d1, ploop
+	
+	move.l #$40000002, d3,
+	move.l d3, (a1)
+	move.l d3, base_cmd.w
+
+	lea Message(pc), a6
+	moveq #0, d0
+	bsr print_string
+	
+	
+	
+	move.w #$8144, (a1) ;enable display
+	move #$2300, sr
+	
+
+wait_forever
+	bra wait_forever
+
+Message:
+	dc.b "Journey From Darkness - Strider Returns (U) [c][!].bin", $A
+	dc.b "Toejam & Earl in Panic on Funkotron (U) [!].bin", $A
+	dc.b "Fire Shark (U) [c][!].bin", $A
+	dc.b "Sonic and Knuckles (W) [!].bin", 0
+
+	align 1
+
+;Prints a null terminated string
+;a6 - pointer to string
+;a0 - VDP data port
+;d0 - base tile attribute
+;
+;Clobbers: d1.w, d2.w, d3.l
+print_string:
+	lea widths(pc), a5
+	move.w x_pos.w, d2
+	move.l base_cmd.w, d3
+.loop
+	moveq #0, d1
+	move.b (a6)+, d1
+	beq .end
+	cmp.b #$A, d1
+	beq .newline
+	tst.b (-32, a5, d1.w)
+	beq .narrow
+	add.w d0, d1
+	move.w d1, (a0)
+	addq #2, d2
+	bra .loop
+.narrow
+	add.w d0, d1
+	move.w d1, (a0)
+	addq #1, d2
+	move.l d2, d1
+	;add.w d1, d1
+	and.w #$FFFE, d1
+	swap d1
+	eor.l #$20000000, d3
+	or.l d3, d1
+	move.l d1, (a1)
+	bra .loop
+.newline
+	moveq #0, d2
+	and.l #$DFFFFFFF, d3
+	add.l #$00800000, d3
+	move.l d3, (a1)
+	bra .loop
+.end
+	move.w d2, x_pos.w
+	move.l d3, base_cmd.w
+	rts
+
+	align 1
+font:
+	incbin font_interlace_variable.tiles
+fontend
+
+widths:
+	dc.b 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1
+	dc.b 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0
+	dc.b 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1
+	dc.b 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
+	dc.b 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1