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
|
/*
* Copyright (C) 2011 Mark Hills <mark@pogo.org.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*
*/
#include <errno.h>
#include <poll.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include "device.h"
#include "realtime.h"
#define REALTIME_PRIORITY 80
/*
* Raise the priority of the current thread
*
* Return: -1 if priority could not be satisfactorily raised, otherwise 0
*/
static int raise_priority()
{
int max_pri;
struct sched_param sp;
fprintf(stderr, "Setting scheduler priority...\n");
if (sched_getparam(0, &sp)) {
perror("sched_getparam");
return -1;
}
max_pri = sched_get_priority_max(SCHED_FIFO);
sp.sched_priority = REALTIME_PRIORITY;
if (sp.sched_priority > max_pri) {
fprintf(stderr, "Invalid scheduling priority (maximum %d).\n", max_pri);
return -1;
}
if (sched_setscheduler(0, SCHED_FIFO, &sp)) {
perror("sched_setscheduler");
fprintf(stderr, "Failed to set scheduler. Run as root otherwise you "
"may get wow and skips!\n");
}
return 0;
}
/*
* The realtime thread
*/
static void rt_main(struct rt_t *rt)
{
int r;
size_t n;
if (raise_priority() == -1)
return;
while (!rt->finished) {
r = poll(rt->pt, rt->npt, -1);
if (r == -1) {
if (errno == EINTR) {
continue;
} else {
perror("poll");
return;
}
}
for (n = 0; n < rt->ndv; n++)
device_handle(rt->dv[n]);
}
}
static void* launch(void *p)
{
rt_main(p);
return NULL;
}
/*
* Initialise state of realtime handler
*/
void rt_init(struct rt_t *rt)
{
rt->finished = false;
rt->ndv = 0;
rt->npt = 0;
}
/*
* Clear resources associated with the realtime handler
*/
void rt_clear(struct rt_t *rt)
{
}
/*
* Add a device to this realtime handler
*
* Return: -1 if the device could not be added, otherwise 0
* Post: if 0 is returned the device is added
*/
int rt_add_device(struct rt_t *rt, struct device_t *dv)
{
ssize_t z;
/* The requested poll events never change, so populate the poll
* entry table before entering the realtime thread */
z = device_pollfds(dv, &rt->pt[rt->npt], MAX_DEVICE_POLLFDS - rt->npt);
if (z == -1) {
fprintf(stderr, "Device failed to return file descriptors.\n");
return -1;
}
rt->npt += z;
rt->dv[rt->ndv] = dv;
rt->ndv++;
return 0;
}
/*
* Start realtime handling of the given devices
*
* This forks the realtime thread if it is required (eg. ALSA). Some
* devices (eg. JACK) start their own thread.
*
* Return: -1 on error, otherwise 0
*/
int rt_start(struct rt_t *rt)
{
size_t n;
/* If there are any devices which returned file descriptors for
* poll() then launch the realtime thread to handle them */
if (rt->npt > 0) {
fprintf(stderr, "Launching realtime thread to handle devices...\n");
if (pthread_create(&rt->ph, NULL, launch, (void*)rt)) {
perror("pthread_create");
return -1;
}
}
/* FIXME: To avoid audio drop on startup, devices should be
* started after synchronising with the realtime thread */
for (n = 0; n < rt->ndv; n++)
device_start(rt->dv[n]);
return 0;
}
/*
* Stop realtime handling, which was previously started by rt_start()
*/
void rt_stop(struct rt_t *rt)
{
size_t n;
rt->finished = true;
if (rt->npt > 0) {
if (pthread_join(rt->ph, NULL) != 0)
abort();
}
/* Stop audio rolling on devices */
for (n = 0; n < rt->ndv; n++)
device_stop(rt->dv[n]);
}
|
