root/trunk/libffado/src/libieee1394/CycleTimerHelper.h

Revision 864, 4.0 kB (checked in by ppalmers, 13 years ago)

update license to GPLv2 or GPLv3 instead of GPLv2 or any later version. Update copyrights to reflect the new year

Line 
1 /*
2  * Copyright (C) 2005-2008 by Pieter Palmers
3  *
4  * This file is part of FFADO
5  * FFADO = Free Firewire (pro-)audio drivers for linux
6  *
7  * FFADO is based upon FreeBoB
8  *
9  * This program is free software: you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation, either version 2 of the License, or
12  * (at your option) version 3 of the License.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
21  *
22  */
23 #ifndef __CYCLETIMERHELPER_H__
24 #define __CYCLETIMERHELPER_H__
25
26 /**
27  * Implements a DLL based mechanism to track the cycle timer
28  * register of the Ieee1394Service pointed to by the 'parent'.
29  *
30  * A DLL mechanism is performance-wise better suited, since it
31  * does not require an OS call. Hence we run a thread to update
32  * the DLL at regular time intervals, and then use the DLL to
33  * generate a cycle timer estimate for the parent to pass on
34  * to it's clients.
35  *
36  * The idea is to make reading the cycle timer real-time safe,
37  * which isn't (necessarily)the case for the direct raw1394 call,
38  * since it's a kernel call that could block (although the current
39  * implementation is RT safe).
40  *
41  * This also allows us to run on systems not having the
42  * raw1394_read_cycle_timer kernel call. We can always do a normal
43  * read of our own cycle timer register, but that's not very accurate.
44  * The accuracy is improved by this DLL mechanism. Still not as good
45  * as when using the raw1394_read_cycle_timer call, but anyway.
46  *
47  * On the long run this code will also allow us to map system time
48  * on to 1394 time for the current host controller, hence enabling
49  * different clock domains to operate together.
50  */
51
52 #include "libutil/Thread.h"
53 #include "libutil/SystemTimeSource.h"
54 #include "cycletimer.h"
55
56 #include "debugmodule/debugmodule.h"
57
58 class Ieee1394Service;
59
60 class CycleTimerHelper : public Util::RunnableInterface
61 {
62 public:
63     CycleTimerHelper(Ieee1394Service &, unsigned int);
64     CycleTimerHelper(Ieee1394Service &, unsigned int, bool rt, int prio);
65     ~CycleTimerHelper();
66
67     virtual bool Init();
68     virtual bool Execute();
69
70     bool setThreadParameters(bool rt, int priority);
71     bool Start();
72
73     /**
74      * @brief get the current cycle timer value (in ticks)
75      * @note thread safe
76      */
77     uint32_t getCycleTimerTicks();
78
79     /**
80      * @brief get the cycle timer value for a specific time instant (in ticks)
81      * @note thread safe
82      */
83     uint32_t getCycleTimerTicks(uint64_t now);
84
85     /**
86      * @brief get the current cycle timer value (in CTR format)
87      * @note thread safe
88      */
89     uint32_t getCycleTimer();
90
91     /**
92      * @brief get the cycle timer value for a specific time instant (in CTR format)
93      * @note thread safe
94      */
95     uint32_t getCycleTimer(uint64_t now);
96
97     float getRate();
98     float getNominalRate();
99
100     void setVerboseLevel(int l);
101
102 private:
103     Ieee1394Service &m_Parent;
104     Util::SystemTimeSource m_TimeSource;
105     // parameters
106     uint32_t m_ticks_per_update;
107     uint32_t m_usecs_per_update;
108
109     float               m_avg_wakeup_delay;
110
111     // state variables
112     double m_dll_e2;
113
114     double m_current_time_usecs;
115     double m_next_time_usecs;
116     double m_current_time_ticks;
117     double m_next_time_ticks;
118     bool m_first_run;
119     ffado_microsecs_t m_sleep_until;
120
121     // cached vars used for computation
122     struct compute_vars {
123         uint64_t usecs;
124         uint64_t ticks;
125         double rate;
126     };
127
128     struct compute_vars m_current_vars;
129     pthread_mutex_t m_compute_vars_lock;
130
131     // Threading
132     Util::Thread *  m_Thread;
133     bool            m_realtime;
134     unsigned int    m_priority;
135
136     // debug stuff
137     DECLARE_DEBUG_MODULE;
138 };
139 #endif
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