blob: 2aa5d88316b4bf26e1784ceb3a33df33968a3004 (
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
|
; vector table fields
@let vector_table 0x10
@let vt_ISRO 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
; 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
; 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
@label hlt_isr
ldi 0x55 RE
hlt
@label keyboard_isr
spu RA ; use RA, RB
spu RB
ldi vt_kb_pp_addr RA ; RA := 0x17 Keyboard peripheral address pointer
ldr RA RA ; RA := 0xE001 Keyboard peripheral address deref
ldr RA RA ; RA := <16-bit keyboard character code> from MMIO register
ldi vt_term_pp_addr RB ; RB := 0x16 Terminal peripheral address pointer
ldr RB RB ; RB := 0xE000 Terminal peripheral address deref
str RA RB ; terminal <- character code
spo RB ; restore RA, RB
spo RA
rti
@label program_segment
@address 0x0
; set up stack pointer to point to beginning of stack segment
ldi vt_stack_addr RA
ldr RA RF
; 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
@address program_segment
; set up address for program code
|
