learn the operating system

... 0); // Close the files close(infd); close(outfd); Figure 6-36. A program fragment for copying a file using the UNIX system calls. This fragment is in C because Java hides the low-level system calls ... hardware) Context Valid Physical page Virtual page tag Flags (b) (c) Format is entirely defined by the operating system Translation table (Operating system) TSB (MMU + sofware) Context Entry 0 is shared by all virtual pages ending ... main class p = new producer( ); // create the producer c = new consumer( ); // create the consumer p.start( ); // start the producer c.start( ); // start the consumer } // This is a utility function...

Ngày tải lên: 12/12/2013, 09:15

Ngày tải lên: 19/03/2014, 13:35

... architectures. Today, the concept of an extensible operating system is once again gaining acceptance this time as the solution to the unconstrained growth of UNIX. During the last 20 years operating systems and their ... tasks. Many other operating systems have met with this problem. Often these systems solve the problem by using inside knowledge of the algorithms used to manage secondary storage. Unfortunately, the Mach ... of the 8th Symposium on Operating System Principles, pages 64-75. December, 1981. [16] Rashid, R.F. From RIG to Accent to Mach: The Evolution of a Network Operating System. In Proceedings of the...

Ngày tải lên: 12/09/2012, 15:05

... with system messages—messages generated and dispatched by the system. The Message Protocols appendix of the Be Book defines all the system messages. In short, system messages fall into the following categories: Application ... posted message becomes the next in the queue, the looper invokes DispatchMessage() to pass the message to the target handler. The effect is for the posted message to reach the target handler’s ... sev- eral examples of the creating of messages and the dispatching of these messages both by the object that created them and by other objects. Figure 9-1. The inheritance hierarchy for the Application...

Ngày tải lên: 17/10/2013, 19:15

... For the Save file panel, the display of the panel comes when the user chooses the Save As item from the File menu. In response to the message issued by the system to the appropriate MessageReceived() ... control is in the hands of the user. Once the user confirms a choice (whether it’s a file selection in the Open file panel, a click on the Save button in the Save file panel, or a click on the Can- cel ... in either type of panel), a message is automatically sent by the system to the panel’s target. By default the panel’s target is the application object, but this can be changed (either in the BFilePanel...

Ngày tải lên: 20/10/2013, 10:15

Ngày tải lên: 25/11/2013, 11:07

... during the execution of a program. An object can be added or deleted from the heap without regard for its placement in the heap, or for the other contents of the heap. The stack, on the other hand, ... such tasks. The zoom- ing and moving of windows is handled by the system, not by the SimpleApp code. This simple demonstration emphasizes the power of the BeOS system software—it is the system software ... window’s tab) • The type of the window (the look and feel of the window) • The behavior of the window (whether it has a resize knob, and so forth) Recall from your C++ background that when the definition...

Ngày tải lên: 26/01/2014, 07:20

... file with the same name as the project (and thus the same name as the application that will be built from the project). The header file holds the definition of the class derived from the BApplication ... any resizing of the window. The final BView constructor parameter determines the types of notifications the view is to receive from the system. The Be constant B_WILL_DRAW means that the view should ... stated that the header file that bears the name of the project should hold the declaration of the project’s application class the class derived from the BApplication class. Here you see that the HelloWorld.h...

Ngày tải lên: 26/01/2014, 07:20

... to another window. Class Descriptions and the Be Book The definitive source of information for the many classes that make up the BeOS software kits is the Be class reference by the programmers of the ... to them, some of their classes appear throughout the book. See the description of the Support Kit below for a specific example concerning the BLocker class. Application Kit The classes of the ... created in the application constructor, the MyHelloWindow constructor is responsible for creating a new view, adding the view to the new window, and then displaying the new window. The new MyHelloWorld...

Ngày tải lên: 26/01/2014, 07:20

... was clicked. The values of the point are in the view’s coor- dinate system. For example, if the cursor was over the very top left corner of the view at the time of the mouse click, the point’s ... If the point (100.1, 49.9) is used instead, the result is the same the win- dow’s corner ends up 100 pixels from the left and 50 pixels from the top of the screen. The above scenario begs the ... the window (to the top view), rather than to another view, so both views are on the same level in the window’s view hierar- chy. The Draw() function of each view type includes code to frame the...

Ngày tải lên: 26/01/2014, 07:20

... done in the Draw() function, where a call to MovePenTo() ensures that the drawing will start in the top left corner of the view (and, because the view is the same size as the window, the top ... FillRegion(fThreeRectRegion); } Implementing the MouseDown() routine for the MyDrawView class is as easy as comparing the cursor location (supplied by the system when it automatically invokes MouseDown()) to the area of the region. The ... defines one of the four edges of a rectangle. The values of the left and right members are relative to the left edge of the view that is to hold the rectangle, while the values of the top and bottom...

Ngày tải lên: 26/01/2014, 07:20

... the BWindow hook function Zoom() to shrink or enlarge the window. To allocate the handling of a message to one of its views, the window passes the message to the affected view, and the view then ... on it, as for a button), the system passes the applica- tion-defined message to the window. How the window handles the message is determined by the code you include in the BWindow member function MessageReceived(). Control ... values to the variables to be used in the control’s con- structor • Create the control using new and the control’s constructor • Attach the control to the window by adding it to one of the window’s...

Ngày tải lên: 26/01/2014, 07:20

... as the item’s label when the user pulls down the menu in which the item appears. The message parameter assigns a message of a particular type to the menu item. When the user chooses the item, the ... given the variable used to represent the sub- menu the name subMenu, it really is nothing more than a BMenu object. The items in the Dogs submenu were added the same way as the items in the Animal menu—by ... all of these items need to be shifted within the window, it would make sense to have all of the items attached to a view within the window rather than to the win- dow itself. Then a call to the...

Ngày tải lên: 26/01/2014, 07:20

... When the contents of the view a scrollbar is attached to exceed the size of the view, the scrollbar’s knob appears and the scrollbar becomes enabled. As the content of the view increases, the ... the window, so the default state for the BStringView text has the text starting 10 pixels from the left edge of the win- dow. Figure 8-6 makes it clear that this isn’t the starting point of the ... snippet produces the text shown in the window in Figure 8-4: BFont theFont(be_plain_font); theFont.SetSize(24.0); theFont.SetRotation(45.0); theView->SetFont(&theFont); theView->MovePenTo(70.0,...

Ngày tải lên: 26/01/2014, 07:20

... is on the same network as one of its interfaces and it can sent the packet directly to the destination and not another router. l Since the exit interface is on an directly connected Ethernet ... 0/1 172.16.1.2/24 23 LAN Interfaces l Ethernet and Fast Ethernet interfaces l Connects the router to the LAN Ÿ Layer 2 MAC address Ÿ Participates in the Ethernet Ÿ Address Resolution Protocol ... the process of how the router determines which path to use when forwarding a packet. l To determine the best path, the router searches its routing table for a network address that matches the...

Ngày tải lên: 09/03/2014, 13:20

Ngày tải lên: 18/03/2014, 00:20

Ngày tải lên: 07/04/2014, 15:52

Ngày tải lên: 28/06/2014, 02:20

Ngày tải lên: 01/07/2014, 17:30