II. Programming Technologies

Transcription

1 II. Programming Technologies II.1 The machine code program Code of algorithm steps + memory addresses: MOV AX,1234h ;0B8h 34h 12h - number (1234h) to AX register MUL WORD PTR [5678h] ;0F7h 26h 78h 56h - multiply AX with the data of the given address (extra segment) MOV [5678h],AX ;0A3h 78h 56h - write back the result in AX to the address II.2 Program making programs Source code program >> Compiler/Interpreter >> Executable program

2 Generation of Languages 1GL: machine code 2GL: assembly (mnemonics) 3GL: high-level procedural: FORTRAN, PASCAL, C 4GL: problem oriented: Functional: LISP (LISt Processing), Logical: PROLOG (PROgraming LOGics), Database management: SQL, Object-oriented: C++, JAVA. C#, Component based development languages. 5GL: natural languages??? Timeline of programming languages Some interesting dates: 1 st : Eniac coding system (von Neumann and others ) BASIC (Kemeny/Kurtz- 1964), Altair BASIC (Bill Gates, Paul Allen 1975), Commodore BASIC (1975), IBM BASIC (made by Microsoft 1981) Pascal (Niklaus Wirth /Kathleen Jensen 1970) C (Dennis Ritchie ), C++ (Bjarne Stroustrup ), C# (Anders Hejlsberg 2000, Java (James Gosling Sun Microsystem 1995)

3 II.3. Data and Programs [const readonly] type_name variable_name [, ][= starting_value] Integers: byte / sbyte / byte ushort/ short / byte uint, int / byte Logical type Bool false..true 1 byte Floating point (real number) type Float byte Double ± ± , 2.1e6, 3.4F, 4.2L 8 byte Decimal (-7.9 x x ) / ( ) 28, 29 digits Letters: Char A, \n, \t (!!!) 2 byte String Apple n*2byte Enumerated lists: Enum enum number {one, two, three} // 0,1,2 enum thislist {a=6,b=11} // number.two

4 II.3.2 Basic algorithm elements II Concatenation int i = 3; int j = 4; int k = i + j; II Alternation (selection) if (i > j) { k = i - j; } else { k = j - i;} i t p f II Iteration (cycling) i = 0; k = 0; while (i < 10) { k += i++;} p t/f f/t

5 II.4. Subprograms, Functions type_name name ([parameters]) { // function body [local definitions, declarations] [statemens] [return [value]; // if exists] } call fv call fv fv return SP Usage modes: function_name([param1, param2, ]); i = name([param1, param2, ]); int main () {}

6 II.5 Object, class (to be discussed in details in seminars) Program Data Object

7 II.6. Windows is an event-driven program Windows Message queue WinMain Message Loop CallBack namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_click( object sender, EventArgs e) { Console.Beep(); } } } Case DefWindowProc

8 Maximum CPU utilization? Multiprogramming. Several processes are kept in memory at one time. Any process can take over the CPU. Process Scheduler is the component of the OS. Scheduling of the CPU is fundamental to OS design. Scheduling Objectives: Share time fairly among processes Prevent starvation of a process Use the processor efficiently Have low overhead Prioritise processes when necessary

9 Windows NT-based operating systems (including Windows 8.x and 10.x) use a multilevel feedback queue. 32 priority levels are predefined. General rules: Give preference to short jobs. Give preference to I/O bound processes. Quickly establish the nature of a process and schedule the process accordingly. All processes receive a priority boost after a wait event, but processes that have experienced a keyboard I/O wait get a larger boost than those that have experienced a disk I/O wait.

10 II.7. Windows pre-emptive multiprogramming System and application waiting queues Devices Printer Disks Keyboard Mouse System Message s Waiting line Applications Message s 32 bit waiting thread queue 32 bit waiting thread queue 32 bit 16bit app waiting thread queue waiting primary queue System VM MS-DOS S VM MS-DOS VM Timeslice distribution with variable priorities 32 Bit apps thread 1 pr=4 thread pr= Bit apps thread 3 pr=16 thread pr=20 4 thread pr=12 5 Primary schedule r 2 4 Timeslice distrib

11 II.8. Rapid Application Development Environment Component based development: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_click(object sender, EventArgs e) { button1.text = "alma"; BackColor = System.Drawing.Color.Red; }

12 }}

13 II.9. Microsoft.Net

14 Aim: Safe development Platform - independency Network solutions CLI C ommon L anguage I nfrastructure C# Managed C++ VB.Net JScript J# etc. CIL C ommon Web services Existing functions (file open) Web/Windows user layer Data with multilevel type checking ( XML - e X tensible M arkup L anguage ) Basic Classes CLR C ommon L anguage R untime ( Code runs on virtual machine New, CLR functions (garbage collection) I ntermediate L anguage CTS C ommon T ype S trudcture JIT J ust I n T ime compiler Operating System