mmu.hpp

一个嵌入式系统的C代码

//*************************************************************************
//  MODULE : MMU - Devide driver class for a memory manager               *
//  AUTHOR : Ron Chernich                                                 *
//  PURPOSE: An RCOS Memory Management Unit device driver must respond to *
//           the messages and format in this module.  The strategy of how *
//           this is implemented my vary with different boby code modules *
//  HISTORY:                                                              *
//    22-APR-93 First version                                             *
//    17-MAR-95 Partitions uped to 16 from 8 for additional users         *
//*************************************************************************

#ifndef _RCOS_MMU_

  #include "rcos.hpp"
  #include "kernel.hpp"
  #include "message.hpp"


  #define PART_SIZE     1024    // fixed partition size (words)
  #define MAX_PARTS     16      // maxim number of partitions


  ///////////////////
  // MMU dependant page table structure .. very simple in this case
  //
  typedef struct pgtbl {
    UINT16 *pMem;               // pointer to actual RAM
    BOOL   bInUse;              // flag set when allocated
  } PGTBL, *PPGTBL;


  ////////////////////////
  // This is the MMU "driver" (based as usual on the port class)
  //
  class Mmu : public port {
    UINT16 *pMemBlk;                // memory block managed by driver
    PGTBL  arrPgTbl[MAX_PARTS];     // array of pages in main memory
    HANDLE FindFree (PPGTBL);       // get a free page handle
  public:
    Mmu (UINT16, UINT16, Knl*);     // constructor
    ~Mmu (void);                    // destructir
    void RxPort (PMSG);             // supply virtual member of "port"
  };

  #define _RCOS_MMU_

#endif

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