50 lines
2.4 KiB
Text
50 lines
2.4 KiB
Text
Some notes about porting DOSBox to systems with certain restrictions,
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like handheld devices.
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General:
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- depending on where you start off with the port, assure that the
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config.h entries are correct/exhausting, like GCC_ATTRIBUTE is
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required (struct packing) but is undefined if you base the port
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on msvc sources which have a special config.h
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If memory is a constraint:
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- in paging.h out-comment the USE_FULL_TLB define to enable special
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TLB linking code that uses less memory
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drawback: none (the code is not heavily tested though)
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gain: reduces memory requirements about ~15mb
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- in render.h lower the scaler integration:
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#define RENDER_USE_ADVANCED_SCALERS 1
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or
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#define RENDER_USE_ADVANCED_SCALERS 0
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drawback: complex scalers and the scaler cache are disabled,
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be sure to test if this affects speed!
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with define RENDER_USE_ADVANCED_SCALERS==0 most simple
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scalers are disabled as well, some graphics modes won't
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work due to reduced cache sizes
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gain: ~2mb with RENDER_USE_ADVANCED_SCALERS==1
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~5mb with RENDER_USE_ADVANCED_SCALERS==0
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- in dos_system.h reduce the drive cache entries:
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#define MAX_OPENDIRS 256
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drawback: some apps might not work with large directory trees
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gain: ~1mb per mounted drive
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- remove the GUS emulation (gus.cpp, especially GUSRam[1024*1024] )
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drawback: no gravis ultrasound
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gain: reduces memory requirements about 1mb
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- reduce the size of the emulated graphics memory:
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see the memory sizing in SVGA_Setup_*, especially the defaults
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in vga_s3.cpp's SVGA_Setup_S3Trio
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drawback: some graphics modes won't work then
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gain: reduces memory requirements
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TODO: fully check this, introduce hard limits
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If speed is a constraint:
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- see if the simple core is faster, possibly remove the normal core
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set the simple core as default
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drawback: one game is known to not work with the simple core;
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the simple core does only work for games which don't use paging
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(when paging is requested the normal core is used automatically)
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gain: the simple core should be somewhat faster
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TODO: add possibility to easily remove the normal core, use fullcore fallback
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- raise the default frameskip value
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drawback: minor graphics smoothness loss for some games (video playback)
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gain: reduces graphics load
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