Original subtitles

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- [Instructor] We've already seen

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a couple of simple programs in Assembler,

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so let's look at their structure.

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In our first MASM program,

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we can see that we start with an include file

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from the MASM32 folder.

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Let's see what this looks like.

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The file we've included starts after its initial comments

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by setting some key MASM configuration items.

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At line 32, we can see the library specifies

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a 486 architecture,

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which sets the assembler up for 32 bit code.

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It uses the flat 32 bit addressing memory model

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and establishes case sensitivity.

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It then brings in a set of include files

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and their corresponding libraries for Windows

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so that we're ready to make calls

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to the Windows application programming interface,

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Note that we have include statements

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for kernel32.lib and user32.lib.

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The next thing we see in our MASM program

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is that our code is divided into two sections.

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The first starting at line two with a .data declaration

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and the second starting at line four with .code.

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At line five, we have the start label

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and at line eight,

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the end start statement identifies

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start as the entry point for the program.

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So the basic structure for a program

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is to set up the processor and memory model

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and bring in any external files,

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which in this case we do by including masm32rt.inc,

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define data in a .data segment,

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define code in the .code segment,

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and then end the program with the name of the entry point.

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Let's close the project

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and select File, New Project.

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We'll again, make it a MASM project

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and the classic console application.

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And we'll take the default name.

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Easy Code has provided a program skeleton for us.

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This has a couple of extra sections that we didn't use.

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The .Const section is used to declare Constance.

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This allows us to have a named constant

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rather than just using the value in our code.

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For instance, we could add a line, answer

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EQU

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42,

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and note that you can also use equal sign instead of EQU,

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and then at line 18, we can put in mov,

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eax comma,

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answer.

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If we select Build, Compile Project1,

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it assembles just fine.

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The data question mark section at line five

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is used to declare variables

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that we don't need to initialize.

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This saves a significant amount of space in the program

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by not having to carry a pre-initialized data area.

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The skeleton is designed to allow us to use the Windows API

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and so starts by making a call at line 13

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to get module handle,

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which returns a handle to the program itself

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in the register Eax.

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This is then stored in hinst

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so that we can use it when we need to during our coding.

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The skeleton code uses an exit process

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as the preferred method of closing down the program

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which also ensures any attached DLLs

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are properly closed down.

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Setting zero on the exit process

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indicates that the program is exiting with no errors.

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Okay, I'll close this project.

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We'll not be focusing on the intricacies of creating

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fully featured Windows GUI programs in Assembler,

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but let's see what the program skeleton looks like

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when we do elect to build a standard Windows executable.

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We'll select File, New Project,

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and we'll select a MASM Windows executable.

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MASM Windows executable file.

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The program skeleton is somewhat more complicated

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as this provides the code necessary to create a window.

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Note in particular that at line 18

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it invokes to get command line

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and then invokes its own WinMain function

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which appears further down.

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We'll learn more about Windows calls later in the course.