blob: 0fe2a9d11fcdf27293652fe34d861cfdaa1b7a74 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
@let sp RH
; vector table fields
@let vector_table 0x10
@let vt_ISR0 0x10 ; ISR0
@let vt_ISR1 0x11 ; ISR1
@let vt_ISR2 0x12 ; ISR2
@let vt_ISR3 0x13 ; ISR3
@let vt_stack_addr 0x14 ; Stack address
@let vt_term_pp_addr 0x15 ; Terminal peripheral address
@let vt_kb_pp_addr 0x16 ; Keyboard peripheral address
@let vt_gr_mode_addr 0x17 ; Graphics mode setting address
@let vt_sprite_mem 0x18 ; Sprite memory address
@let vt_text_mem 0x19 ; Text memory buffer address
; memory segments
@let stack_segment 0x8000
@let mmio_segment 0xE000
@let terminal_addr 0xE000
@let keyboard_addr 0xE001
@let gr_mode_addr 0xE002
@let sprite_mem 0xE800
@let text_mem 0xF800 ; to 0xFFFF
; note: sprite memory & text memory can use the same space
; since they are never used at the same time
; graphics mode settings
@let gr_disabled_mode 0b00
@let gr_text_mode 0b01
@let gr_sprite_mode 0b10
@address vector_table
keyboard_isr ; 0x10
hlt_isr ; 0x11
hlt_isr ; 0x12
hlt_isr ; 0x13
stack_segment ; 0x14
terminal_addr ; 0x15
keyboard_addr ; 0x16
gr_mode_addr ; 0x17
sprite_mem ; 0x18
text_mem ; 0x19
@label hlt_isr
ldi 0x55 RE
hlt
@label keyboard_isr
spu RA
spu RB
ldi vt_kb_pp_addr RA ; RA := Keyboard peripheral address pointer
ldr RA RA ; RA := Keyboard peripheral address deref
ldr RA RA ; RA := <16-bit keyboard character code> from MMIO register
ldi vt_term_pp_addr RB ; RB := Terminal peripheral address pointer
ldr RB RB ; RB := Terminal peripheral address deref
str RA RB ; terminal <- character code (ASCII?)
mov RA RE ; RE := character code (for debugging)
spo RB
spo RA
rti
@label program_segment
; define short prelude that sets up vital instructions
; NOTE: must be shorter than the vector table offset
@address 0x0
; set up stack pointer to point to beginning of stack segment
ldi vt_stack_addr RA
ldr RA SP
jpi program_segment
@address program_segment
; set graphics mode to disabled
ldi vt_gr_mode_addr RA
ldr RA RA
ldi gr_disabled_mode RB
str RB RA
; jump to main (user defined)
jpi main
|
