/
audio.asm
254 lines (215 loc) · 5.75 KB
/
audio.asm
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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
; audio routines
; use ffmpeg to convert an audio file for playback:
; ffmpeg -i input.mp3 -f s16le -ac 1 -ar 22050 audio.raw
const AUDIO_POINTER_0: 0x01FFFF00 ; 4 bytes
const AUDIO_POINTER_1: 0x01FFFF04 ; 4 bytes
const AUDIO_POINTER_2: 0x01FFFF08 ; 4 bytes
const AUDIO_POINTER_3: 0x01FFFF0C ; 4 bytes
const AUDIO_LENGTH_0: 0x01FFFF10 ; 4 bytes
const AUDIO_LENGTH_1: 0x01FFFF14 ; 4 bytes
const AUDIO_LENGTH_2: 0x01FFFF18 ; 4 bytes
const AUDIO_LENGTH_3: 0x01FFFF1C ; 4 bytes
const OLD_BUFFER_SWAP_VECTOR_0: 0x01FFFF20 ; 4 bytes
const OLD_BUFFER_SWAP_VECTOR_1: 0x01FFFF24 ; 4 bytes
const OLD_BUFFER_SWAP_VECTOR_2: 0x01FFFF28 ; 4 bytes
const OLD_BUFFER_SWAP_VECTOR_3: 0x01FFFF2C ; 4 bytes
; play an audio clip (does not block)
; inputs:
; r0: pointer to audio clip
; r1: length of audio clip in bytes (must be a multiple of 32768 bytes)
; r2: audio sample rate
; r3: audio channel (0-3)
; outputs:
; none
play_audio:
push r0
push r1
cmp r3, 0
ifz jmp play_audio_0
cmp r3, 1
ifz jmp play_audio_1
cmp r3, 2
ifz jmp play_audio_2
cmp r3, 3
ifz jmp play_audio_3
jmp play_audio_done
play_audio_0:
; set the interrupt vector for interrupt 0xFE
; save the old one only if it wasn't already saved earlier
cmp [OLD_BUFFER_SWAP_VECTOR_0], refill_buffer_0
ifnz mov [OLD_BUFFER_SWAP_VECTOR_0], [0x000003F8]
mov [0x000003F8], refill_buffer_0
; store audio pointer
mov [AUDIO_POINTER_0], r0
; store audio length
; floor it to the nearest multiple of 32768
and r1, 0xFFFF8000
mov [AUDIO_LENGTH_0], r1
; enable audio playback and set sample rate
mov r0, 0x80000600
out r0, r2
; initial buffer fill
int 0xFE
jmp play_audio_done
play_audio_1:
; set the interrupt vector for interrupt 0xFD
; save the old one only if it wasn't already saved earlier
cmp [OLD_BUFFER_SWAP_VECTOR_1], refill_buffer_1
ifnz mov [OLD_BUFFER_SWAP_VECTOR_1], [0x000003F4]
mov [0x000003F4], refill_buffer_1
; store audio pointer
mov [AUDIO_POINTER_1], r0
; store audio length
; floor it to the nearest multiple of 32768
and r1, 0xFFFF8000
mov [AUDIO_LENGTH_1], r1
; enable audio playback and set sample rate
mov r0, 0x80000601
out r0, r2
; initial buffer fill
int 0xFD
jmp play_audio_done
play_audio_2:
; set the interrupt vector for interrupt 0xFC
; save the old one only if it wasn't already saved earlier
cmp [OLD_BUFFER_SWAP_VECTOR_2], refill_buffer_2
ifnz mov [OLD_BUFFER_SWAP_VECTOR_2], [0x000003F0]
mov [0x000003F0], refill_buffer_2
; store audio pointer
mov [AUDIO_POINTER_2], r0
; store audio length
; floor it to the nearest multiple of 32768
and r1, 0xFFFF8000
mov [AUDIO_LENGTH_2], r1
; enable audio playback and set sample rate
mov r0, 0x80000602
out r0, r2
; initial buffer fill
int 0xFC
jmp play_audio_done
play_audio_3:
; set the interrupt vector for interrupt 0xFB
; save the old one only if it wasn't already saved earlier
cmp [OLD_BUFFER_SWAP_VECTOR_3], refill_buffer_3
ifnz mov [OLD_BUFFER_SWAP_VECTOR_3], [0x000003EC]
mov [0x000003EC], refill_buffer_3
; store audio pointer
mov [AUDIO_POINTER_3], r0
; store audio length
; floor it to the nearest multiple of 32768
and r1, 0xFFFF8000
mov [AUDIO_LENGTH_3], r1
; enable audio playback and set sample rate
mov r0, 0x80000603
out r0, r2
; initial buffer fill
int 0xFB
play_audio_done:
pop r1
pop r0
ret
; stop audio playback
; inputs:
; r0: audio channel (0-3)
; outputs:
; none
stop_audio:
push r0
; disable audio playback
or r0, 0x80000600
out r0, 0
; restore the old buffer refill vector
cmp.8 r0, 0
ifz mov [0x000003F8], [OLD_BUFFER_SWAP_VECTOR_0]
cmp.8 r0, 1
ifz mov [0x000003F4], [OLD_BUFFER_SWAP_VECTOR_1]
cmp.8 r0, 2
ifz mov [0x000003F0], [OLD_BUFFER_SWAP_VECTOR_2]
cmp.8 r0, 3
ifz mov [0x000003EC], [OLD_BUFFER_SWAP_VECTOR_3]
pop r0
ret
refill_buffer_0:
add rsp, 4
push r0
push r1
push r31
mov r31, 8192 ; 32768 bytes = 8192 words
mov r0, [AUDIO_POINTER_0]
mov r1, 0x0212C000 ; buffer 0 address
refill_buffer_0_loop:
mov [r1], [r0]
add r0, 4
add r1, 4
loop refill_buffer_0_loop
mov [AUDIO_POINTER_0], r0
sub [AUDIO_LENGTH_0], 32768
ifz mov r0, 0
ifz call stop_audio
pop r31
pop r1
pop r0
reti
refill_buffer_1:
add rsp, 4
push r0
push r1
push r31
mov r31, 8192 ; 32768 bytes = 8192 words
mov r0, [AUDIO_POINTER_1]
mov r1, 0x02134000 ; buffer 1 address
refill_buffer_1_loop:
mov [r1], [r0]
add r0, 4
add r1, 4
loop refill_buffer_1_loop
mov [AUDIO_POINTER_1], r0
sub [AUDIO_LENGTH_1], 32768
ifz mov r0, 1
ifz call stop_audio
pop r31
pop r1
pop r0
reti
refill_buffer_2:
add rsp, 4
push r0
push r1
push r31
mov r31, 8192 ; 32768 bytes = 8192 words
mov r0, [AUDIO_POINTER_2]
mov r1, 0x02290000 ; buffer 2 address
refill_buffer_2_loop:
mov [r1], [r0]
add r0, 4
add r1, 4
loop refill_buffer_2_loop
mov [AUDIO_POINTER_2], r0
sub [AUDIO_LENGTH_2], 32768
ifz mov r0, 2
ifz call stop_audio
pop r31
pop r1
pop r0
reti
refill_buffer_3:
add rsp, 4
push r0
push r1
push r31
mov r31, 8192 ; 32768 bytes = 8192 words
mov r0, [AUDIO_POINTER_3]
mov r1, 0x02298000 ; buffer 3 address
refill_buffer_3_loop:
mov [r1], [r0]
add r0, 4
add r1, 4
loop refill_buffer_3_loop
mov [AUDIO_POINTER_3], r0
sub [AUDIO_LENGTH_3], 32768
ifz mov r0, 3
ifz call stop_audio
pop r31
pop r1
pop r0
reti