dreamcast/regs/maple_host_bits.csv

1	register_name	enum_name	bits	bit_name	value	mask	description
2	host_instruction		31	end_flag	1
3
4	host_instruction	port_select	17-16	a	0
5	host_instruction	port_select	17-16	b	1
6	host_instruction	port_select	17-16	c	2
7	host_instruction	port_select	17-16	d	3
8
9	host_instruction	pattern	10-8	normal	0b000
10	host_instruction	pattern	10-8	light_gun_mode	0b010
11	host_instruction	pattern	10-8	reset	0b011
12	host_instruction	pattern	10-8	return_from_light_gun_mode	0b100
13	host_instruction	pattern	10-8	nop	0b111
14
15	host_instruction		7-0	transfer_length		0xff
16
17	ap	port_select	7-6	a	0b00
18	ap	port_select	7-6	b	0b01
19	ap	port_select	7-6	c	0b10
20	ap	port_select	7-6	d	0b11
21
22	ap	de	5	device	1
23	ap	de	5	expansion_device	0
24	ap	de	5	port	0
25
26	ap	lm_bus	4-0	_4	0b10000
27	ap	lm_bus	4-0	_3	0b01000
28	ap	lm_bus	4-0	_2	0b00100
29	ap	lm_bus	4-0	_1	0b00010
30	ap	lm_bus	4-0	_0	0b00001