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◆ main openmsx / src / video / VRAMObserver.hh
1.5 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#ifndef VRAMOBSERVER_HH
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#define VRAMOBSERVER_HH
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#include "EmuTime.hh"
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namespace openmsx {
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/** Interface that can be registered at VRAMWindow,
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  * to be called when the contents of the VRAM inside that window change.
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  */
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class VRAMObserver {
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public:
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	/** Informs the observer of a change in VRAM contents.
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	  * This update is sent just before the change,
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	  * so the subcomponent can update itself to the given time
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	  * based on the old contents.
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	  * @param offset Offset of byte that will change,
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	  *               relative to window base address.
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	  * @param time The moment in emulated time this change occurs.
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	  */
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	virtual void updateVRAM(unsigned offset, EmuTime time) = 0;
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	/** Informs the observer that the entire VRAM window will change.
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	  * This update is sent just before the change,
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	  * so the subcomponent can update itself to the given time
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	  * based on the old contents.
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	  * This happens if the base/index masks are changed,
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	  * or if the window becomes disabled.
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	  * TODO: Separate enable/disable from window move?
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	  * @param enabled Will the window be enabled after the change?
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	  *     If the observer keeps a cache which is based on VRAM contents,
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	  *     it is only necessary to flush the cache if the new window
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	  *     is enabled, because no reads are allowed from disabled windows.
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	  * @param time The moment in emulated time this change occurs.
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	  */
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	virtual void updateWindow(bool enabled, EmuTime time) = 0;
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protected:
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	~VRAMObserver() = default;
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};
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} // namespace openmsx
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#endif