forked from dashxdr/SDL_basic
-
Notifications
You must be signed in to change notification settings - Fork 0
/
sound.c
172 lines (157 loc) · 3.35 KB
/
sound.c
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
/*
SDL_basic written by David Ashley, released 20080621 under the GPL
http://www.linuxmotors.com/SDL_basic
dashxdr@gmail.com
*/
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#include "misc.h"
#define SAMPLING_RATE 48000
#define FRAGSIZE (1024)
#define PIECES 16
#define CHUNK (1024/PIECES) // timed for fragsize of 1024
#define FFIX (4294967296.0/SAMPLING_RATE)
#define TIME_PER_PIECE ((double)1024 / (SAMPLING_RATE*PIECES))
void fillaudio(void *data, Uint8 *buffer, int len)
{
bc *bc=data;
int i, sp;
Sint16 *p;
sound *s, *is;
int accum[16384], *ap;
Uint32 v, dv;
int vol;
double soundtime;
int now;
int diff;
int left;
int chunk;
int next;
now = SDL_GetTicks();
p = (void *)buffer;
len>>=2; // stereo, 16 bit signed samples = 4 bytes/sample
//printf("%10.3f %10.3f %10.3f\n", bc->time, bc->soundtime, bc->time - bc->soundtime);
soundtime = bc->soundtime;
next = CHUNK - bc->leftover;
left = len;
while(left>0)
{
chunk = next;
if(chunk>left)
chunk = left;
left -= chunk;
next -= chunk;
memset(accum, 0, chunk*2*sizeof(accum[0]));
for(sp = 0;sp < MAX_SOUNDS;++sp)
{
s = bc->sounds + sp;
is = bc->isounds + sp;
diff = s->count - is->count;
if(diff>0 && (s->flags & (SND_ACTIVE | SND_QUIET)) &&
soundtime >= s->start)
{
v=is->index;
*is = *s;
is->index = v;
if(is->flags & SND_QUIET)
is->flags &=~SND_ACTIVE;
is->flags &= ~SND_QUIET;
}
s = is;
if(~s->flags & SND_ACTIVE)
continue;
ap = accum;
v = s->index;
dv = FFIX * s->frequency;
vol = s->volume * 16384;
if(sp < MAX_SOUNDS-4) // last 4 are noise
{
for(i=0;i<chunk;++i)
{
v += dv;
ap[i*2+0] += (s->wave[(v>>19) & 0x1fff] * vol) >> 17;
ap[i*2+1] += (s->wave[(v>>19) & 0x1fff] * vol) >> 17;
}
} else
{
int t = ~0, t2, t3=0;
for(i=0;i<chunk;++i)
{
v += dv;
t2 = v>>31;
if(t != t2)
{
t = t2;
t3 = (rand() & 0x1fff) - 4096;
}
ap[i*2+0] += t3*vol >> 14;
ap[i*2+1] += t3*vol >> 14;
}
}
s->index = v;
if(next) continue;
s->time += TIME_PER_PIECE;
if(s->time >= s->duration)
s->flags &= ~SND_ACTIVE;
s->frequency *= s->fmul;
if(s->frequency > SAMPLING_RATE/2 || s->frequency < 4)
s->flags &= ~SND_ACTIVE;
}
ap = accum;
for(i=0;i<chunk;++i)
{
*p++ = *ap++;
*p++ = *ap++;
}
if(!next)
{
soundtime += TIME_PER_PIECE;
next = CHUNK;
}
}
bc->leftover = CHUNK - next;
bc->soundtime += (now - bc->soundticks)*.001;
bc->soundticks = now;
}
void soundopen(bc *bc)
{
SDL_AudioSpec wanted;
int i;
sound *s;
for(i=0;i<MAX_SOUNDS;++i)
{
s=bc->sounds + i;
s->flags = 0;
s->frequency = 440.0;
s->volume = 1.0;
s->duration = 0.0;
s->fmul = 1.0;
s->time = 0.0;
s->count = 0;
bc->isounds[i] = *s;
}
for(i=0;i<8192;++i)
{
bc->wsqr[i] = (i<4096) ? -0x8000 : 0x7fff;
bc->wsin[i] = 0x7fff*sin(i*3.1415927/4096.0);
bc->wtri[i] = (i<4096) ? -0x8000 + i*8 : 0xffff - i*8;
bc->wsaw[i] = -0x8000 + i*8;
}
memset(&wanted,0,sizeof(wanted));
wanted.freq=SAMPLING_RATE;
wanted.channels=2;
wanted.format=AUDIO_S16;
wanted.samples=FRAGSIZE;
wanted.callback=fillaudio;
wanted.userdata=bc;
if(SDL_OpenAudio(&wanted,0)<0)
{
fprintf(stderr,"Couldn't open audio: %s\n",SDL_GetError());
return;
}
bc->samples = wanted.samples;
bc->soundworking = 1;
SDL_PauseAudio(0);
}