neslib/vram_unrle.s at master · 8bitworkshop/neslib · GitHub

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

.importzp TEMP
.include "nes.inc"
.include "zpvars.inc"
.export _vram_unrle

;void __fastcall__ vram_unrle(const unsigned char *data);

_vram_unrle:

	tay
	stx <RLE_HIGH
	lda #0
	sta <RLE_LOW

	lda (RLE_LOW),y
	sta <RLE_TAG
	iny
	bne @1
	inc <RLE_HIGH

@1:

	lda (RLE_LOW),y
	iny
	bne @11
	inc <RLE_HIGH

@11:

	cmp <RLE_TAG
	beq @2
	sta PPU_DATA
	sta <RLE_BYTE
	bne @1

@2:

	lda (RLE_LOW),y
	beq @4
	iny
	bne @21
	inc <RLE_HIGH

@21:

	tax
	lda <RLE_BYTE

@3:

	sta PPU_DATA
	dex
	bne @3
	beq @1

@4:

	rts