Mercurial > sdl-ios-xcode
annotate src/thread/beos/SDL_syssem.c @ 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 |
| 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 | |
|
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6 modify it under the terms of the GNU Lesser General Public |
| 0 | 7 License as published by the Free Software Foundation; either |
|
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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 | |
|
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13 Lesser General Public License for more details. |
| 0 | 14 |
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15 You should have received a copy of the GNU Lesser General Public |
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16 License along with this library; if not, write to the Free Software |
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 0 | 18 |
| 19 Sam Lantinga | |
|
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20 slouken@libsdl.org |
| 0 | 21 */ |
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22 #include "SDL_config.h" |
| 0 | 23 |
| 24 /* Semaphores in the BeOS environment */ | |
| 25 | |
| 26 #include <be/kernel/OS.h> | |
| 27 | |
| 28 #include "SDL_thread.h" | |
| 29 | |
| 30 | |
| 31 struct SDL_semaphore { | |
| 32 sem_id id; | |
| 33 }; | |
| 34 | |
| 35 /* Create a counting semaphore */ | |
| 36 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) | |
| 37 { | |
| 38 SDL_sem *sem; | |
| 39 | |
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40 sem = (SDL_sem *)SDL_malloc(sizeof(*sem)); |
| 0 | 41 if ( sem ) { |
| 42 sem->id = create_sem(initial_value, "SDL semaphore"); | |
| 43 if ( sem->id < B_NO_ERROR ) { | |
| 44 SDL_SetError("create_sem() failed"); | |
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45 SDL_free(sem); |
| 0 | 46 sem = NULL; |
| 47 } | |
| 48 } else { | |
| 49 SDL_OutOfMemory(); | |
| 50 } | |
| 51 return(sem); | |
| 52 } | |
| 53 | |
| 54 /* Free the semaphore */ | |
| 55 void SDL_DestroySemaphore(SDL_sem *sem) | |
| 56 { | |
| 57 if ( sem ) { | |
| 58 if ( sem->id >= B_NO_ERROR ) { | |
| 59 delete_sem(sem->id); | |
| 60 } | |
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61 SDL_free(sem); |
| 0 | 62 } |
| 63 } | |
| 64 | |
| 65 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) | |
| 66 { | |
| 67 int32 val; | |
| 68 int retval; | |
| 69 | |
| 70 if ( ! sem ) { | |
| 71 SDL_SetError("Passed a NULL semaphore"); | |
| 72 return -1; | |
| 73 } | |
| 74 | |
| 75 tryagain: | |
| 76 if ( timeout == SDL_MUTEX_MAXWAIT ) { | |
| 77 val = acquire_sem(sem->id); | |
| 78 } else { | |
| 79 timeout *= 1000; /* BeOS uses a timeout in microseconds */ | |
| 80 val = acquire_sem_etc(sem->id, 1, B_RELATIVE_TIMEOUT, timeout); | |
| 81 } | |
| 82 switch (val) { | |
| 83 case B_INTERRUPTED: | |
| 84 goto tryagain; | |
| 85 case B_NO_ERROR: | |
| 86 retval = 0; | |
| 87 break; | |
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Date: Sat, 17 Sep 2005 13:38:49 +0200
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88 case B_TIMED_OUT: |
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89 retval = SDL_MUTEX_TIMEDOUT; |
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Date: Sat, 17 Sep 2005 13:38:49 +0200
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90 break; |
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Date: Sat, 17 Sep 2005 13:38:49 +0200
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91 case B_WOULD_BLOCK: |
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Date: Sat, 17 Sep 2005 13:38:49 +0200
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92 retval = SDL_MUTEX_TIMEDOUT; |
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ab0154afe938
Date: Sat, 17 Sep 2005 13:38:49 +0200
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parents:
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93 break; |
| 0 | 94 default: |
| 95 SDL_SetError("acquire_sem() failed"); | |
| 96 retval = -1; | |
| 97 break; | |
| 98 } | |
| 99 | |
| 100 return retval; | |
| 101 } | |
| 102 | |
| 103 int SDL_SemTryWait(SDL_sem *sem) | |
| 104 { | |
| 105 return SDL_SemWaitTimeout(sem, 0); | |
| 106 } | |
| 107 | |
| 108 int SDL_SemWait(SDL_sem *sem) | |
| 109 { | |
| 110 return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT); | |
| 111 } | |
| 112 | |
| 113 /* Returns the current count of the semaphore */ | |
| 114 Uint32 SDL_SemValue(SDL_sem *sem) | |
| 115 { | |
| 116 int32 count; | |
| 117 Uint32 value; | |
| 118 | |
| 119 value = 0; | |
| 120 if ( sem ) { | |
| 121 get_sem_count(sem->id, &count); | |
| 122 if ( count > 0 ) { | |
| 123 value = (Uint32)count; | |
| 124 } | |
| 125 } | |
| 126 return value; | |
| 127 } | |
| 128 | |
| 129 /* Atomically increases the semaphore's count (not blocking) */ | |
| 130 int SDL_SemPost(SDL_sem *sem) | |
| 131 { | |
| 132 if ( ! sem ) { | |
| 133 SDL_SetError("Passed a NULL semaphore"); | |
| 134 return -1; | |
| 135 } | |
| 136 | |
| 137 if ( release_sem(sem->id) != B_NO_ERROR ) { | |
| 138 SDL_SetError("release_sem() failed"); | |
| 139 return -1; | |
| 140 } | |
| 141 return 0; | |
| 142 } |