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

Revision 1531, 5.0 kB (checked in by ppalmers, 12 years ago)

svn merge -r 1506:HEAD svn+ssh://ffadosvn@ffado.org/ffado/branches/libffado-2.0

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 "libutil/Functors.h"
57 #include "libutil/Mutex.h"
58
59 #include "debugmodule/debugmodule.h"
60
61 class Ieee1394Service;
62
63 class CycleTimerHelper : public Util::RunnableInterface
64 {
65 public:
66     CycleTimerHelper(Ieee1394Service &, unsigned int);
67     CycleTimerHelper(Ieee1394Service &, unsigned int, bool rt, int prio);
68     ~CycleTimerHelper();
69
70     virtual bool Init();
71     virtual bool Execute();
72
73     bool setThreadParameters(bool rt, int priority);
74     bool Start();
75
76     /**
77      * @brief get the current cycle timer value (in ticks)
78      * @note thread safe
79      */
80     uint32_t getCycleTimerTicks();
81
82     /**
83      * @brief get the cycle timer value for a specific time instant (in ticks)
84      * @note thread safe
85      */
86     uint32_t getCycleTimerTicks(uint64_t now);
87
88     /**
89      * @brief get the current cycle timer value (in CTR format)
90      * @note thread safe
91      */
92     uint32_t getCycleTimer();
93
94     /**
95      * @brief get the cycle timer value for a specific time instant (in CTR format)
96      * @note thread safe
97      */
98     uint32_t getCycleTimer(uint64_t now);
99
100     /**
101      * @brief get the system time for a specific cycle timer value (in ticks)
102      * @note thread safe
103      */
104     uint64_t getSystemTimeForCycleTimerTicks(uint32_t ticks);
105
106     /**
107      * @brief get the system time for a specific cycle timer value (in CTR format)
108      * @note thread safe
109      */
110     uint64_t getSystemTimeForCycleTimer(uint32_t ctr);
111
112     float getRate();
113     float getNominalRate();
114
115     /**
116      * @brief handle a bus reset
117      */
118     void busresetHandler();
119
120     void setVerboseLevel(int l);
121
122 private:
123     bool readCycleTimerWithRetry(uint32_t *cycle_timer, uint64_t *local_time, int ntries);
124     bool initValues();
125
126 #if IEEE1394SERVICE_USE_CYCLETIMER_DLL
127     bool initDLL();
128 #endif
129
130     Ieee1394Service &m_Parent;
131     // parameters
132     uint32_t m_ticks_per_update;
133     uint32_t m_usecs_per_update;
134
135     float    m_avg_wakeup_delay;
136
137     // state variables
138     double m_dll_e2;
139
140     double m_current_time_usecs;
141     double m_next_time_usecs;
142     double m_current_time_ticks;
143     double m_next_time_ticks;
144     bool m_first_run;
145     ffado_microsecs_t m_sleep_until;
146
147     uint32_t m_cycle_timer_prev;
148     uint64_t m_cycle_timer_ticks_prev;
149
150     double m_dll_coeff_b;
151     double m_dll_coeff_c;
152
153     // cached vars used for computation
154     struct compute_vars {
155         uint64_t usecs;
156         uint64_t ticks;
157         double rate;
158     };
159
160     #define CTRHELPER_NB_SHADOW_VARS 8
161     struct compute_vars m_shadow_vars[CTRHELPER_NB_SHADOW_VARS];
162     volatile unsigned int m_current_shadow_idx;
163
164     // Threading
165     Util::Thread *  m_Thread;
166     bool            m_realtime;
167     unsigned int    m_priority;
168     Util::Mutex*    m_update_lock;
169
170     // busreset handling
171     Util::Functor* m_busreset_functor;
172     bool            m_unhandled_busreset;
173
174 #ifdef DEBUG
175     uint64_t m_last_loop_entry;
176     int m_successive_short_loops;
177 #endif
178
179     // debug stuff
180     DECLARE_DEBUG_MODULE;
181 };
182 #endif
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