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Editors Note: The original patch was modified to use SDL_Delay() instead of nanosleep because nanosleep may not be portable to all systems using SDL with the ALSA backend. This may be a moot point with the switch to blocking writes anyway... Date: Sat, 27 Dec 2003 21:47:36 +0100 From: Michel Daenzer To: Debian Bug Tracking System Subject: [SDL] Bug#225252: [PATCH] ALSA fixes Package: libsdl1.2debian-all Version: 1.2.6-2 Severity: normal Tags: patch For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU usage, interrupted sound and stuttering in some games here. Taking a nanosleep whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more efficient to use blocking mode for the actual sound playback. Feedback from the SDL and ALSA lists appreciated. The patch also fixes the default ALSA device to be used.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 04 Jan 2004 15:40:50 +0000
parents e5bc29de3f0a
children 355632dca928
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>Chapter 12. Multi-threaded Programming</A
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>Table of Contents</B
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><DT
><A
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>SDL_CreateThread</A
> &#8212; Creates a new thread of execution that shares its parent's properties.</DT
><DT
><A
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>SDL_ThreadID</A
> &#8212; Get the 32-bit thread identifier for the current thread.</DT
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>SDL_GetThreadID</A
> &#8212; Get the SDL thread ID of a SDL_Thread</DT
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>SDL_WaitThread</A
> &#8212; Wait for a thread to finish.</DT
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> &#8212; Gracelessly terminates the thread.</DT
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> &#8212; Create a mutex</DT
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> &#8212; Destroy a mutex</DT
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> &#8212; Creates a new semaphore and assigns an initial value to it.</DT
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>SDL_DestroySemaphore</A
> &#8212; Destroys a semaphore that was created by <A
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>SDL_SemWait</A
> &#8212; Lock a semaphore and suspend the thread if the semaphore value is zero.</DT
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> &#8212; Attempt to lock a semaphore but don't suspend the thread.</DT
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> &#8212; Lock a semaphore, but only wait up to a specified maximum time.</DT
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> &#8212; Restart a thread wait on a condition variable</DT
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> &#8212; Wait on a condition variable</DT
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>SDL provides functions for creating threads, mutexes, semphores and condition variables.</P
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>Don't call SDL video/event functions from separate threads</P
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>Don't use any library functions in separate threads</P
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>Don't perform any memory management in separate threads</P
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>Lock global variables which may be accessed by multiple threads</P
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>Never terminate threads, always set a flag and wait for them to quit</P
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>Think very carefully about all possible ways your code may interact</P
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>SDL's threading is not implemented on MacOS, due to that lack of preemptive thread support (MacOS X dos nt suffer from this problem)</P
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