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
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
|
; Example of using playroutine 1 in multispeed
;
; playeraddress+0 = init music (A = tunenumber starting from 0)
; playeraddress+3 = play music
;
; Remember that this player uses 2 zeropage locations, so save those
; locations before calling the player, if you need all of the ZP.
; The player doesn't depend on their contents between calls at all!
;
; For multispeed operation, simply call playeraddress+3 many times
; per frame.
processor 6502
org 2048
getin = $ffe4
start: jsr initraster
lda #22
sta $d018
lda #$00
jsr $1000 ;Initialize song 0
ldx #$00
lda #$20
clearscreen: sta $0400,x
sta $0500,x
sta $0600,x
sta $0700,x
inx
bne clearscreen
textloop: lda text,x
jsr convertascii
sta $0400,x
lda #$01
sta $d800,x
inx
cpx #5*40
bcc textloop
ldx #$00
authorloop: lda $1020,x
jsr convertascii
sta $0458,x
inx
cpx #32
bne authorloop
idle: lda currraster
ldx #52
jsr printhex
lda maxraster
ldx #55
jsr printhex
jmp idle
printhex: pha
lsr
lsr
lsr
lsr
tay
lda hexnybble,y
jsr convertascii
sta $0400,x
pla
and #$0f
tay
lda hexnybble,y
jsr convertascii
sta $0401,x
rts
convertascii: cmp #$60
bcc ca_ok
sbc #$60
ca_ok: rts
initraster: sei
lda #<raster
sta $0314
lda #>raster
sta $0315
lda #50 ;Set low bits of raster
sta $d012 ;position
lda $d011
and #$7f ;Set high bit of raster
sta $d011 ;position (0)
lda #$7f ;Set timer interrupt off
sta $dc0d
lda #$01 ;Set raster interrupt on
sta $d01a
lda $dc0d ;Acknowledge timer interrupt
cli
irwait: lda maxraster
beq irwait
lda #$00
sta maxraster
rts
raster: nop
nop
nop
nop
nop
lda $d012
sta raster_cmp+1
inc $d020
jsr $1003 ;Play music and measure
lda $d012 ;rastertime it took to
dec $d020 ;execute
sec
raster_cmp: sbc #$00
clc
adc accraster
sta accraster
cmp maxraster
bcc raster_skip
sta maxraster
raster_skip: dec $d019
ldy nextraster
bne raster_skip2
sty accraster
sta currraster
raster_skip2: tya
eor #$01
tax
sta nextraster
lda rasterlinetbl,x
sta $d012
jmp $ea31
text: dc.b "Example 3: Multispeed-musicroutine "
dc.b "Rastertime: / "
dc.b "Author: "
dc.b " "
dc.b " "
hexnybble: dc.b "0123456789ABCDEF"
maxraster: dc.b 0
accraster: dc.b 0
currraster: dc.b 0
nextraster: dc.b 0
rasterlinetbl: dc.b 50,210
org $1000
incbin example3.bin
|
