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49 lines
2.3 KiB
Plaintext
49 lines
2.3 KiB
Plaintext
Some notes about porting DOSBox to systems with certain restrictions,
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like handheld devices.
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If memory is a constraint:
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- in paging.h reduce the size of the TLB:
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#define TLB_SIZE (64*1024)
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the 64 gives access to the first 256mb of linear memory
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drawback: some protected mode games won't work then
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gain: reduces memory requirements about ~15mb
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TODO: limit vmemory access to the size of the TLB,
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otherwise games which use >256mb vaddresses will crash badly
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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 whith 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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- in vga.h reduce the size of the emulated graphics memory:
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#define VGA_MEMORY (1*1024*1024)
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drawback: some graphics modes won't work then
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[EDIT: many modes won't work due to pixel caches]
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gain: reduces memory requirements about 1mb
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TODO: get this to actually work;
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remove the respective svga modes, adapt some svga registers
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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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