Initial version

code/filesys/synchdisk.h

@@ -0,0 +1,53 @@
+// synchdisk.h 
+// 	Data structures to export a synchronous interface to the raw 
+//	disk device.
+//
+// Copyright (c) 1992-1993 The Regents of the University of California.
+// All rights reserved.  See copyright.h for copyright notice and limitation 
+// of liability and disclaimer of warranty provisions.
+
+#include "copyright.h"
+
+#ifndef SYNCHDISK_H
+#define SYNCHDISK_H
+
+#include "disk.h"
+#include "synch.h"
+
+// The following class defines a "synchronous" disk abstraction.
+// As with other I/O devices, the raw physical disk is an asynchronous device --
+// requests to read or write portions of the disk return immediately,
+// and an interrupt occurs later to signal that the operation completed.
+// (Also, the physical characteristics of the disk device assume that
+// only one operation can be requested at a time).
+//
+// This class provides the abstraction that for any individual thread
+// making a request, it waits around until the operation finishes before
+// returning.
+class SynchDisk:public dontcopythis {
+  public:
+    SynchDisk(const char* name);    	// Initialize a synchronous disk,
+					// by initializing the raw Disk.
+    ~SynchDisk();			// De-allocate the synch disk data
+    
+    void ReadSector(int sectorNumber, void* data);
+    					// Read/write a disk sector, returning
+    					// only once the data is actually read 
+					// or written.  These call
+    					// Disk::ReadRequest/WriteRequest and
+					// then wait until the request is done.
+    void WriteSector(int sectorNumber, const void* data);
+    
+    void RequestDone();			// Called by the disk device interrupt
+					// handler, to signal that the
+					// current disk operation is complete.
+
+  private:
+    Disk *disk;		  		// Raw disk device
+    Semaphore *semaphore; 		// To synchronize requesting thread 
+					// with the interrupt handler
+    Lock *lock;		  		// Only one read/write request
+					// can be sent to the disk at a time
+};
+
+#endif // SYNCHDISK_H