gbdk-2020 | GameBoy Development Kit |
| download: https://git.y1.nz/archives/gbdk.tar.gz | |
| README | Files | Log | Refs | LICENSE |
gbdk-lib/libc/targets/sm83/init_tt.s
1 .include "global.s"
2
3 .area _HOME
4
5 ;; Initialize window tile table with B
6 .init_wtt::
7 LDH A,(.LCDC)
8 AND #LCDCF_WIN9C00
9 JR Z,.is98
10 JR .is9c
11 ;; Initialize background tile table with B
12 .init_btt::
13 LDH A,(.LCDC)
14 AND #LCDCF_BG9C00
15 JR NZ,.is9c
16 .is98:
17 LD HL,#0x9800 ; HL = origin
18 JR .init_tt
19 .is9c:
20 LD HL,#0x9C00 ; HL = origin
21
22 .init_tt::
23 LD DE,#0x0400 ; One whole GB Screen
24
25 .init_vram::
26 SRL D
27 RR E
28 JR NC, 1$
29
30 WAIT_STAT
31 LD A, B
32 LD (HL+),A
33 1$:
34 LD A, D
35 OR E
36 RET Z
37
38 INC D
39 INC E
40 JR 2$
41 3$:
42 WAIT_STAT
43 LD A, B
44 LD (HL+),A
45 LD (HL+),A
46 2$:
47 DEC E
48 JR NZ, 3$
49 DEC D
50 JR NZ, 3$
51
52 RET
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