46 lines
1.8 KiB
C++
46 lines
1.8 KiB
C++
// translate.h
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// Data structures for managing the translation from
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// virtual page # -> physical page #, used for managing
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// physical memory on behalf of user programs.
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//
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// The data structures in this file are "dual-use" - they
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// serve both as a page table entry, and as an entry in
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// a software-managed translation lookaside buffer (TLB).
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// Either way, each entry is of the form:
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// <virtual page #, physical page #>.
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//
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// DO NOT CHANGE -- part of the machine emulation
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//
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// Copyright (c) 1992-1993 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#ifndef TLB_H
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#define TLB_H
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#include "copyright.h"
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#include "utility.h"
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// The following class defines an entry in a translation table -- either
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// in a page table or a TLB. Each entry defines a mapping from one
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// virtual page to one physical page.
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// In addition, there are some extra bits for access control (valid and
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// read-only) and some bits for usage information (use and dirty).
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class TranslationEntry {
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public:
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unsigned int virtualPage; // The page number in virtual memory, only when
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// using a TLB
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unsigned int physicalPage; // The page number in real memory (relative to the
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// start of "mainMemory"
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bool valid; // If this bit is cleared, the translation is ignored.
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// (In other words, the entry hasn't been initialized.)
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bool readOnly; // If this bit is set, the user program is not allowed
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// to modify the contents of the page.
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bool use; // This bit is set by the hardware every time the
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// page is referenced or modified.
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bool dirty; // This bit is set by the hardware every time the
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// page is modified.
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};
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#endif
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