Mercurial > sdl-ios-xcode
annotate include/SDL_mutex.h @ 4216:5b99971a27b4 SDL-1.2
Fixed bug #698
Hans de Goede 2009-02-13 01:10:52 PST
Since the new "glitch free" version of pulseaudio (used in Fedora 10 amongst
others), the sound of SDL using apps (like a simple playmus call) has been
crackling.
While looking in to fixing this I noticed that the current pulseaudio code in
SDL uses pa_simple. However pa_simple uses a thread to pump pulseaudio events
and ipc, given that SDL already has its own thread for audio handling this is
clearly suboptimal, leading to unnecessary context switching IPC, etc. Also
pa_simple does not allow one to implement the WaitAudio() callback for SDL
audiodrivers properly.
Given that my work is mostly a rewrite (although some original pieces remain)
I'm attaching the new .c and .h file, as that is easier to review then the huge
diff.
Let me know if you also want the diff.
This new version has the following features:
-no longer use an additional thread next to the SDL sound thread
-do not crackle with glitch free audio
-when used with a newer pulse, which does glitch free audio, the total latency
is
the same as with the alsa driver
-proper WaitAudio() implementation, saving another mixlen worth of latency
-adds a WaitDone() implementation
This patch has been written in consultancy with Lennart Poetering (the
pulseaudio author) and has been reviewed by him for correct use of the pa API.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 21 Sep 2009 09:27:08 +0000 |
| parents | a1b03ba2fcd0 |
| children | 4c4113c2162c |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
| 4159 | 3 Copyright (C) 1997-2009 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
1263
diff
changeset
|
6 modify it under the terms of the GNU Lesser General Public |
| 0 | 7 License as published by the Free Software Foundation; either |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
1263
diff
changeset
|
8 version 2.1 of the License, or (at your option) any later version. |
| 0 | 9 |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
1263
diff
changeset
|
13 Lesser General Public License for more details. |
| 0 | 14 |
|
1312
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
1263
diff
changeset
|
15 You should have received a copy of the GNU Lesser General Public |
|
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
1263
diff
changeset
|
16 License along with this library; if not, write to the Free Software |
|
c9b51268668f
Updated copyright information and removed rcs id lines (problematic in branch merges)
Sam Lantinga <slouken@libsdl.org>
parents:
1263
diff
changeset
|
17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 0 | 18 |
| 19 Sam Lantinga | |
|
251
b8688cfdc232
Updated the headers with the correct e-mail address
Sam Lantinga <slouken@libsdl.org>
parents:
0
diff
changeset
|
20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 #ifndef _SDL_mutex_h | |
| 24 #define _SDL_mutex_h | |
| 25 | |
| 26 /* Functions to provide thread synchronization primitives | |
| 27 | |
| 28 These are independent of the other SDL routines. | |
| 29 */ | |
| 30 | |
|
1356
67114343400d
*** empty log message ***
Sam Lantinga <slouken@libsdl.org>
parents:
1312
diff
changeset
|
31 #include "SDL_stdinc.h" |
|
1358
c71e05b4dc2e
More header massaging... works great on Windows. ;-)
Sam Lantinga <slouken@libsdl.org>
parents:
1356
diff
changeset
|
32 #include "SDL_error.h" |
| 0 | 33 |
| 34 #include "begin_code.h" | |
| 35 /* Set up for C function definitions, even when using C++ */ | |
| 36 #ifdef __cplusplus | |
| 37 extern "C" { | |
| 38 #endif | |
| 39 | |
| 40 /* Synchronization functions which can time out return this value | |
| 41 if they time out. | |
| 42 */ | |
| 43 #define SDL_MUTEX_TIMEDOUT 1 | |
| 44 | |
| 45 /* This is the timeout value which corresponds to never time out */ | |
| 46 #define SDL_MUTEX_MAXWAIT (~(Uint32)0) | |
| 47 | |
| 48 | |
| 49 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ | |
| 50 /* Mutex functions */ | |
| 51 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ | |
| 52 | |
| 53 /* The SDL mutex structure, defined in SDL_mutex.c */ | |
| 54 struct SDL_mutex; | |
| 55 typedef struct SDL_mutex SDL_mutex; | |
| 56 | |
| 57 /* Create a mutex, initialized unlocked */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
58 extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void); |
| 0 | 59 |
| 60 /* Lock the mutex (Returns 0, or -1 on error) */ | |
| 61 #define SDL_LockMutex(m) SDL_mutexP(m) | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
62 extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex); |
| 0 | 63 |
|
417
04ec6995f75d
*** empty log message ***
Sam Lantinga <slouken@libsdl.org>
parents:
337
diff
changeset
|
64 /* Unlock the mutex (Returns 0, or -1 on error) |
|
04ec6995f75d
*** empty log message ***
Sam Lantinga <slouken@libsdl.org>
parents:
337
diff
changeset
|
65 It is an error to unlock a mutex that has not been locked by |
|
04ec6995f75d
*** empty log message ***
Sam Lantinga <slouken@libsdl.org>
parents:
337
diff
changeset
|
66 the current thread, and doing so results in undefined behavior. |
|
04ec6995f75d
*** empty log message ***
Sam Lantinga <slouken@libsdl.org>
parents:
337
diff
changeset
|
67 */ |
| 0 | 68 #define SDL_UnlockMutex(m) SDL_mutexV(m) |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
69 extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex); |
| 0 | 70 |
| 71 /* Destroy a mutex */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
72 extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex); |
| 0 | 73 |
| 74 | |
| 75 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ | |
| 76 /* Semaphore functions */ | |
| 77 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ | |
| 78 | |
| 79 /* The SDL semaphore structure, defined in SDL_sem.c */ | |
| 80 struct SDL_semaphore; | |
| 81 typedef struct SDL_semaphore SDL_sem; | |
| 82 | |
| 83 /* Create a semaphore, initialized with value, returns NULL on failure. */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
84 extern DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value); |
| 0 | 85 |
| 86 /* Destroy a semaphore */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
87 extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem); |
| 0 | 88 |
| 89 /* This function suspends the calling thread until the semaphore pointed | |
| 90 * to by sem has a positive count. It then atomically decreases the semaphore | |
| 91 * count. | |
| 92 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
93 extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem); |
| 0 | 94 |
| 95 /* Non-blocking variant of SDL_SemWait(), returns 0 if the wait succeeds, | |
| 96 SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error. | |
| 97 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
98 extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem); |
| 0 | 99 |
| 100 /* Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if | |
| 101 the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in | |
| 102 the allotted time, and -1 on error. | |
| 103 On some platforms this function is implemented by looping with a delay | |
| 104 of 1 ms, and so should be avoided if possible. | |
| 105 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
106 extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms); |
| 0 | 107 |
| 108 /* Atomically increases the semaphore's count (not blocking), returns 0, | |
| 109 or -1 on error. | |
| 110 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
111 extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem); |
| 0 | 112 |
| 113 /* Returns the current count of the semaphore */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
114 extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem); |
| 0 | 115 |
| 116 | |
| 117 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ | |
| 118 /* Condition variable functions */ | |
| 119 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ | |
| 120 | |
| 121 /* The SDL condition variable structure, defined in SDL_cond.c */ | |
| 122 struct SDL_cond; | |
| 123 typedef struct SDL_cond SDL_cond; | |
| 124 | |
| 125 /* Create a condition variable */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
126 extern DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void); |
| 0 | 127 |
| 128 /* Destroy a condition variable */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
129 extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond); |
| 0 | 130 |
| 131 /* Restart one of the threads that are waiting on the condition variable, | |
| 132 returns 0 or -1 on error. | |
| 133 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
134 extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond); |
| 0 | 135 |
| 136 /* Restart all threads that are waiting on the condition variable, | |
| 137 returns 0 or -1 on error. | |
| 138 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
139 extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond); |
| 0 | 140 |
| 141 /* Wait on the condition variable, unlocking the provided mutex. | |
| 142 The mutex must be locked before entering this function! | |
|
1263
3bdcef7e1c90
*** empty log message ***
Sam Lantinga <slouken@libsdl.org>
parents:
769
diff
changeset
|
143 The mutex is re-locked once the condition variable is signaled. |
| 0 | 144 Returns 0 when it is signaled, or -1 on error. |
| 145 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
146 extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mut); |
| 0 | 147 |
| 148 /* Waits for at most 'ms' milliseconds, and returns 0 if the condition | |
| 149 variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not | |
| 150 signaled in the allotted time, and -1 on error. | |
| 151 On some platforms this function is implemented by looping with a delay | |
| 152 of 1 ms, and so should be avoided if possible. | |
| 153 */ | |
|
337
9154ec9ca3d2
Explicitly specify the SDL API calling convention (C by default)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
154 extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms); |
| 0 | 155 |
| 156 /* Ends C function definitions when using C++ */ | |
| 157 #ifdef __cplusplus | |
| 158 } | |
| 159 #endif | |
| 160 #include "close_code.h" | |
| 161 | |
| 162 #endif /* _SDL_mutex_h */ |