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
|
/*
* Example program for the Allegro library, by Shawn Hargreaves.
*
* This program shows how to use the audio stream functions to transfer
* large blocks of sample data to the soundcard.
*/
#include "allegro.h"
#define BUFFER_SIZE 1024
int main()
{
AUDIOSTREAM *stream;
int updates = 0;
int pitch = 0;
int val = 0;
int i;
allegro_init();
install_keyboard();
install_timer();
if (set_gfx_mode(GFX_SAFE, 320, 200, 0, 0) != 0) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Unable to set any graphic mode\n%s\n", allegro_error);
return 1;
}
set_palette(desktop_palette);
clear_to_color(screen, makecol(255, 255, 255));
text_mode(makecol(255, 255, 255));
/* install a digital sound driver */
if (install_sound(DIGI_AUTODETECT, MIDI_NONE, NULL) != 0) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Error initialising sound system\n%s\n", allegro_error);
return 1;
}
/* create an audio stream */
stream = play_audio_stream(BUFFER_SIZE, 8, FALSE, 22050, 255, 128);
if (!stream) {
set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
allegro_message("Error creating audio stream!\n");
return 1;
}
textprintf_centre(screen, font, SCREEN_W/2, SCREEN_H/3, makecol(0, 0, 0), "Audio stream is now playing...");
textprintf_centre(screen, font, SCREEN_W/2, SCREEN_H/3+24, makecol(0, 0, 0), "Driver: %s", digi_driver->name);
while (!keypressed()) {
/* does the stream need any more data yet? */
unsigned char *p = get_audio_stream_buffer(stream);
if (p) {
/* if so, generate a bit more of our waveform... */
textprintf_centre(screen, font, SCREEN_W/2, SCREEN_H*2/3, makecol(0, 0, 0), "update #%d", updates++);
for (i=0; i<BUFFER_SIZE; i++) {
/* this is just a sawtooth wave that gradually increases in
* pitch. Obviously you would want to do something a bit more
* interesting here, for example you could fread() the next
* buffer of data in from a disk file...
*/
p[i] = (val >> 16) & 0xFF;
val += pitch;
pitch++;
if (pitch > 0x40000)
pitch = 0x10000;
}
free_audio_stream_buffer(stream);
}
}
stop_audio_stream(stream);
return 0;
}
END_OF_MAIN();
|
