Transcript Part D – Assembler, Compiler & Interpreter

• Assembler
• Compiler
• Interpreter
ASSEMBLER
• To convert the assembly language
into machine code.
• Translate mnemonic operation codes
to their machine language
equivalents.
• Assigning machine addresses to
symbolic labels.
• The assembler can also process
assembler directives.
• Assembler directives (or pseudoinstructions) provide instructions to the
assembler itself. They are not translated
into machine instructions
• E.g.
• START (specify name and starting address for
the program).
• END (indicate the end of the source program
and (optionally) specify the first executable
instruction in the program)
• Programmer write a program using a
sequence of assemble instructions.
• This sequence of assembler instructions,
known as the source code/source
program, then specified to the assembler
program when that program is started.
• It translates a source code into machine
language.
• The output of the assembler program is
called the object code or object program.
• We use Flat Assembler (FASM)
o Download on:
o http://flatassembler.net/
o Download for Windows
• The Linker is the program that ties all the
loose end together and makes a single
program out of the pieces. FASM comes
with its own built in linker
• Go to “Start -> Control Panels -> System -
> Advanced -> Environment Variables
• Make a new system variable, called
include, with value C:\(your directory of
fasm folder)
• Run fasmw.exe
• Note: Please refer to the
http://www.friedspace.com/assembly/first.php
• Inside FASM, open the EXAMPLES
directory, open the directory called
HELLO, open the file Hello.asm
• Go to Run menu, Compile and Run
• The program will assemble and then the
pop message box up on the screen
include 'win32ax.inc' ; you can simply switch between win32ax,
win32wx, win64ax and win64wx here
.code
start:
invoke MessageBox,HWND_DESKTOP,"Hi! I'm the example
program!",invoke GetCommandLine,MB_OK
invoke ExitProcess,0
.end start
• First line, win32ax.in is a special macro file.
• The next line, .code tells the assembler we
are going to include some code now.
• The line start: is a label. It gives a name to
one of the lines.
• The program is ended with the .end
directive. The execution of the program will
begin at this point
• The remaining two line are calls to the
Windows API to tell it to display a message
box and then quit.
COMPILER
• A program that changes source code (highlevel language) to object code which that
can be executed by a machine.
• Compiler:
o Checks syntax of program
o Checks at a time all the program
• Primary reason for compiling source code is
to create an executable program
• Examples of compiler based language:
• C, C++, JAVA
• Executables: Files that actually do
something by carrying out a set of
instructions.
• E.g., .exe files in Windows
• Once the executable is there, it can be
called by the user to process the given
inputs to a program and produce the desired
outputs.
• Some of examples of Compiler:
o Microsoft Visual Studio
o BlueJ
o Quincy 2005
• We use Quincy 2005 (Open Source)
• Link: http://www.codecutter.net/tools/quincy/
• We use C++ programming language.
• Open Quincy 2005.
• File -> New -> C++ Source File -> OK
• File -> Save as.. -> Hello.cpp
• Write the following code:
#include <iostream>
using namespace std;
int main()
{
cout << "Hello World!" << endl;
return 0;
}
• The first line #include <iostream>, input/output
library
• The second line using namespace std; , allows
us to group a set of global classes, objects
and/or functions under a name
• int main() { }, the main function of program
• cout << "Hello World!" << endl; print the “Hello
World!” message to the screen.
• return 0;, terminate the main function of
program. A return value of 0 means that the
program finished correctly
INTERPRETER
• A computer program that executes instructions
written in a programming language and do not
produces the executable file.
• Interpreter:
o Checks the keywords of a program
o Taking one instruction at a time and convert it into machine language
before taking upon the next instruction.
• Examples of interpreter based language:
o PHP, JavaScript, BASIC
• We use JavaScript language.
• JavaScript engine is specialized computer software
which interprets and executes JavaScript. Mostly
used in web browsers.
• Open Notepad -> Save as.. -> Name the file as
hello.html
• Write the following code:
<html>
<body>
<script>
name = prompt("Hello World")
</script>
</body>
</html>
•
•
•
•
<html>, open a html page
<body>, put all the website contents inside
<script), open a script function
name = prompt("Hello World"), shows the Hello
World! Message
• </script>, close the script function
• </body>, close the body of a web page
• </html>, close a html page
• Assembler = To convert the assembly language
into machine code.
• Compiler = A program that changes source code
(high-level language) to object code which that can
be executed by a machine.
• A computer program that executes instructions
written in a programming language and do not
produces the executable file.