blob: 8c53af7973b4171ad8ed3192db9ad2e3e769b704 (
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
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
.segment "CODE"
.proc nmi
;; Should we skip it?
bit Globals::zp_flags
;; If we are on a dev environment, account for any frame drops.
.ifdef PARTIAL
bpl @account_for_frame_drop
.else
bpl @end
.endif
;; Save registers.
pha
txa
pha
tya
pha
;; Sprite DMA.
lda #$00
sta OAM::m_address
lda #$02
sta OAM::m_dma
;; Are we paused? If so skip timers, PAL handler and the likes.
lda #%00001000
and Globals::zp_flags
bne @ppu_registers
;; PAL-specific code
.ifdef PAL
jsr Driver::pal_handler
.endif
;; TODO: some actions here will depend on the status of the game...
lda Globals::zp_flags
and #%00000001
bne @ppu_registers
;; Increase the random seed.
inc Prng::zp_rand
;; Decrease title timer.
lda Title::zp_title_timer
beq @ppu_registers
dec Title::zp_title_timer
@ppu_registers:
;; Should we update PPU registers?
bit Globals::zp_flags
bvc @scroll
;; Zero out the `ppu` flag.
lda #%10111111
and Globals::zp_flags
sta Globals::zp_flags
bit PPU::m_status
;; Update the PPU control/mask registers with shadowed values.
lda PPU::zp_mask
sta PPU::m_mask
lda PPU::zp_control
sta PPU::m_control
@scroll:
;; Always reset the scroll just in case.
bit PPU::m_status
lda #$00
sta PPU::m_scroll
sta PPU::m_scroll
;; Unblock the main code.
lda #%01111111
and Globals::zp_flags
sta Globals::zp_flags
;; Restore registers.
pla
tay
pla
tax
pla
@end:
rti
;; If we are on a dev environment, account for any frame drops.
.ifdef PARTIAL
@account_for_frame_drop:
inc Debug::zp_frame_drops
rti
.endif
.endproc
;; Unused.
.proc irq
rti
.endproc
|
