annotate src/thread/SDL_systhread.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
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997-2009 Sam Lantinga
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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
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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.
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Lesser General Public License for more details.
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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
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19 Sam Lantinga
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20 slouken@libsdl.org
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21 */
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22 #include "SDL_config.h"
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24 /* These are functions that need to be implemented by a port of SDL */
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25
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26 #ifndef _SDL_systhread_h
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27 #define _SDL_systhread_h
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29 #include "SDL_thread.h"
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31 /* This function creates a thread, passing args to SDL_RunThread(),
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32 saves a system-dependent thread id in thread->id, and returns 0
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33 on success.
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34 */
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35 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
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36 extern int SDL_SYS_CreateThread(SDL_Thread *thread, void *args, pfnSDL_CurrentBeginThread pfnBeginThread, pfnSDL_CurrentEndThread pfnEndThread);
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37 #else
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38 extern int SDL_SYS_CreateThread(SDL_Thread *thread, void *args);
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39 #endif
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41 /* This function does any necessary setup in the child thread */
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42 extern void SDL_SYS_SetupThread(void);
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43
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44 /* This function waits for the thread to finish and frees any data
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45 allocated by SDL_SYS_CreateThread()
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46 */
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47 extern void SDL_SYS_WaitThread(SDL_Thread *thread);
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49 /* This function kills the thread and returns */
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50 extern void SDL_SYS_KillThread(SDL_Thread *thread);
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51
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52 #endif /* _SDL_systhread_h */