gbdk-2020 | GameBoy Development Kit |
| download: https://git.y1.nz/archives/gbdk.tar.gz | |
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gbdk-lib/libc/targets/z80/sms_fill_rect_xy.s
1 .include "global.s"
2
3 .title "VRAM utilities"
4 .module VRAMUtils
5
6 .ez80
7
8 .area _HOME
9
10 ;; Set background tile table from (BC) at XY = DE of size WH = HL
11 .fill_rect_xy::
12 push hl
13 ld a, (_shadow_VDP_R2)
14 rlca
15 rlca
16 and #0b01111000
17 ld h, a
18 ld l, #0
19
20 ;; Set background tile from (BC) at YX = DE, size WH on stack, to VRAM from address (HL)
21 .fill_rect_xy_tt::
22 ld a, h
23 ld iyh, a
24 push bc ; Store source
25
26 ld a, d
27 rrca ; rrca(2) == rlca(6)
28 rrca
29 ld d, a
30 and #0x07
31 add h
32 ld b, a
33 ld a, #0xC0
34 and d
35 sla e
36 add e
37 ld c, a ; dest BC = HL + ((0x20 * Y) * 2) + (X * 2)
38
39 ld a, b
40 and #0b00000111
41 or iyh
42 ld b, a
43
44 DISABLE_VBLANK_COPY ; switch OFF copy shadow SAT
45
46 pop hl ; HL = source
47 pop de ; DE = HW
48 push ix ; save IX
49 push de ; store HW
50
51 ld ixh, b
52 ld ixl, c
53 push ix ; store dest
54
55 1$: ; copy H rows
56 VDP_WRITE_CMD ixh, ixl
57 ld c, #.VDP_DATA
58 2$: ; copy W tiles
59 out (c), l
60 VDP_DELAY
61 out (c), h
62
63 ld a, ixl
64 and #0x3F
65 inc a
66 inc a
67 bit 6, a
68 jp z, 3$
69 and #0x3F
70 ld b, a
71 ld a, ixl
72 and #0xC0
73 or b
74 ld ixl, a
75 VDP_WRITE_CMD ixh, ixl
76 dec e
77 jp nz, 2$
78 jp 7$
79 3$:
80 inc ixl
81 inc ixl
82 dec e
83 jp nz, 2$
84 7$:
85 pop ix
86 pop de
87
88 dec d
89 jr z, 6$
90
91 push de
92
93 ld bc, #0x40
94 add ix, bc
95
96 ld a, ixh
97 and #0b00000111
98 cp #0x07
99 jp nz, 8$
100 xor a
101 8$:
102 or iyh
103 ld ixh, a
104
105 push ix
106 jp 1$
107 6$:
108 ENABLE_VBLANK_COPY ; switch ON copy shadow SAT
109 pop ix ; restore IX
110 ret
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