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First shot at new audio data types (int32 and float32). Notable changes: - Converters between types are autogenerated. Instead of making multiple passes over the data with seperate filters for endianess, size, signedness, etc, converting between data types is always one specialized filter. This simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases with the new types, and makes the actually conversions more CPU cache friendly. Left a stub for adding specific optimized versions of these routines (SSE/MMX/Altivec, assembler, etc) - Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This does not need to be run unless tweaking the code, and thus doesn't need integration into the build system. - Went through all the drivers and tried to weed out all the "Uint16" references that are better specified with the new SDL_AudioFormat typedef. - Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them with new SDL_AUDIO_* macros. - Added initial float32 and int32 support code. Theoretically, existing drivers will push these through converters to get the data they want to feed to the hardware. Still TODO: - Optimize and debug new converters. - Update the CoreAudio backend to accept float32 data directly. - Other backends, too? - SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files (both of which exist and can be generated by 'sox' for testing purposes). - Update the mixer to handle new datatypes. - Optionally update SDL_sound and SDL_mixer, etc.
author Ryan C. Gordon <icculus@icculus.org>
date Thu, 24 Aug 2006 12:10:46 +0000
parents f12379c41042
children
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>Multi-threaded Programming</TITLE
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>Chapter 12. Multi-threaded Programming</H1
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>Table of Contents</B
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><DT
><A
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>SDL_CreateThread</A
>&nbsp;--&nbsp;Creates a new thread of execution that shares its parent's properties.</DT
><DT
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>SDL_ThreadID</A
>&nbsp;--&nbsp;Get the 32-bit thread identifier for the current thread.</DT
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>SDL_GetThreadID</A
>&nbsp;--&nbsp;Get the SDL thread ID of a SDL_Thread</DT
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>SDL_WaitThread</A
>&nbsp;--&nbsp;Wait for a thread to finish.</DT
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>SDL_KillThread</A
>&nbsp;--&nbsp;Gracelessly terminates the thread.</DT
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>SDL_CreateMutex</A
>&nbsp;--&nbsp;Create a mutex</DT
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>&nbsp;--&nbsp;Destroy a mutex</DT
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>&nbsp;--&nbsp;Unlock a mutex</DT
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>SDL_CreateSemaphore</A
>&nbsp;--&nbsp;Creates a new semaphore and assigns an initial value to it.</DT
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>SDL_DestroySemaphore</A
>&nbsp;--&nbsp;Destroys a semaphore that was created by <A
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>SDL_CreateSemaphore</A
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>SDL_SemWait</A
>&nbsp;--&nbsp;Lock a semaphore and suspend the thread if the semaphore value is zero.</DT
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>SDL_SemTryWait</A
>&nbsp;--&nbsp;Attempt to lock a semaphore but don't suspend the thread.</DT
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>&nbsp;--&nbsp;Lock a semaphore, but only wait up to a specified maximum time.</DT
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>&nbsp;--&nbsp;Unlock a semaphore.</DT
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>SDL_SemValue</A
>&nbsp;--&nbsp;Return the current value of a semaphore.</DT
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>SDL_CreateCond</A
>&nbsp;--&nbsp;Create a condition variable</DT
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>SDL_DestroyCond</A
>&nbsp;--&nbsp;Destroy a condition variable</DT
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>SDL_CondSignal</A
>&nbsp;--&nbsp;Restart a thread wait on a condition variable</DT
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>SDL_CondBroadcast</A
>&nbsp;--&nbsp;Restart all threads waiting on a condition variable</DT
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>SDL_CondWait</A
>&nbsp;--&nbsp;Wait on a condition variable</DT
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>SDL_CondWaitTimeout</A
>&nbsp;--&nbsp;Wait on a condition variable, with timeout</DT
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>In general, you must be very aware of concurrency and data integrity issues
when writing multi-threaded programs.  Some good guidelines include:
<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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>Note: </B
>SDL's threading is not implemented on MacOS, due to that lack of preemptive thread support (Mac OS X dos nt suffer from this problem)</P
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