_InterlockedExchange_rel() is required for correctness on ARM because
the _ReadWriteBarrier() macro is only a compiler memory barrier, not a
hardware memory barrier. Due to ARM's relaxed memory model, this means
the '*lock = 0' write may be observed before the operations inside the
lock, causing possible corruption of data protected by the lock.
_InterlockedExchange_acq() is more efficient on ARM because it avoids an
expensive full memory barrier that _InterlockedExchange() does.
C.W. Betts
I tested building commit http://hg.libsdl.org/SDL/rev/7adf3fdc19f3 on Mac Catalyst and found some issues:
* MTLFeatureSet_iOS_* enums aren't available under Mac Catalyst.
* OpenGL ES is unavailable under Mac Catalyst.
* Some Metal features are available under Catalyst but not iOS, such as displaySyncEnabled.
* Set Metal as the default renderer on Mac Catalyst
Attaching a patch that will make SDL2 build for Mac Catalyst.
This is unsafe because the event is auto-reset, therefore the call to
WaitForSingleObject() resets the event which GetOverlappedResult() will
try to wait on.
Even though the overlapped operation is guaranteed to be completed at
the point we call GetOverlappedResult(), it will still wait on the event
handle for a short time to trigger the reset for auto-reset events. This
amounts to roughly a 100 ms sleep each time GetOverlappedResult() is called
for a completed I/O with a non-signalled event.
In the context of HIDAPI, this extra sleep means that callers that loop
on hid_read_timeout() with timeout=0 will loop forever, since the 100 ms
sleep each iteration ensures ReadFile() will always have new data.
Caleb Cornett
For a window created with SDL_WINDOW_ALLOW_HIGHDPI, SDL_GL_GetDrawableSize will return the high-dpi drawable size even before any GL context creation happens. But SDL_Metal_GetDrawableSize will return the size of the window if the Metal view has not been created. This is confusing and inconsistent behavior.
An easy way to test this is to build testgl2 and testvulkan on macOS with the SDL_WINDOW_ALLOW_HIGHDPI flag enabled during window creation. The GL2 program will report a drawable size of 2x window width and 2x window height, while the Vulkan program will report the window size.
This patch addresses the issue by falling back to using the content view dimensions if no Metal view exists in the window. (The code for this was taken directly from Cocoa_GL_GetDrawableSize.) With this change, the testvulkan behavior matches that of testgl2.
Note that I haven't tested for this issue on UIKit. It's possible a similar change will need to be made there too.
David Carlier
This form of 'or' provides a hint that performance
will probably be improved if shared resources dedicated
to the executing processor are released for use by other
processors
- hidapi already called CancelIo on hid_close but that only cancels pending IO for the current thread. Controller read/writes originate from multiple
threads (serialized, but on a different thread nonetheless) but device destruction was always done on the main device thread which left any
pending overlapped reads still running after hidapi's internal read buffer is deallocated leading to intermittent free list corruption.
Ozkan Sezer
Cameron Gutman
Sam Lantinga
Sylvain Becker
Manuel Alfayate Corchete