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player.asm @ 1

Last change on this file since 1 was 1, checked in by svn, 5 years ago
Import initial
File size: 1.4 KB

Line
1	****************************************************************
2	****************************************************************
3	(main)player.asm
4
5	ORG $9000
6
7	PSHS U,X,DP,B,A,CC
8
9	ORCC #$50
10	LDA #$FB
11	ANDA $E7CF
12	STA $E7CF
13	LDA #$3F
14	STA $E7CD
15	LDA #$04
16	ORA $E7CF
17	STA $E7CF
18	LDX #$A000
19	STX pos_song
20	BRA loop
21
22	PULS U,X,DP,B,A,CC
23	RTS
24
25	fine fcb 0
26	pos_song fcb $A0,$00
27
28
29
30
31	****************************************************************
32	*
33	*
34	* bank 5
35	* read pattern info
36	* switch to bank
37	* read pattern data
38	* output to DAC
39	* advance in pattern
40	* if necessary, advance in song
41	* try to be less than 64, fixed timing
42	*
43	****************************************************************
44
45	loop
46	LDB #05
47	STB $E7E5
48	LDX pos_song
49	LDB ,x+
50	LDA ,x+
51	TFR x,y
52	* switch to pattern bank
53	STB $E7E5
54	CLRB
55	ADDA #$A0
56	TFR D,X
57	LDB fine
58	ABX
59	LDA ,x
60	STA $E7CD
61	INCB
62	CMPB #160
63	BEQ end_chunk
64	STB fine
65	BRA wait1
66	wait1 BRA wait2
67	wait2 BRA end
68	end_chunk
69	CLR fine
70	STY pos_song
71
72	end
73	* 85 cycles for now ... wait 43
74	MUL
75	MUL
76	MUL
77	NOP
78	NOP
79	BRA pre_end
80	pre_end BRA loop
81
82
83
84	****************************************************************
85	*
86	* Attente de la VBL
87	*
88	****************************************************************
89	VSYNC
90	VSYNC_1
91	TST $E7E7
92	BPL VSYNC_1
93	VSYNC_2
94	TST $E7E7
95	BMI VSYNC_2
96
97	RTS
98
99

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