How to run Assembly Programs in Visual Studio

First, you must install some version of Visual Studio or Visual C++ Express:

1. If you have installed Visual Studio 2008 Professional or Team Suite, these products also contain the Microsoft Assembler 9.0.
2. If you have installed Visual C++ 2008 Express Service Pack 1, it includes the Visual C++ 2008 Feature Pack, which also includes MASM 9.0.
3. If you have installed Visual C++ 2005 Express, you must also download the Microsoft Assembler 8.0
   (see below).

Downloading Microsoft Express Editions

• Visual C++ 2008 Express
• Visual C++ 2005 Express

When you run the setup program for either of these, make a note of the location where the C++ compiler is installed. This information will be useful to you later.

Downloading and installing the Microsoft Assembler 8.0: Visit Microsoft's MASM 8.0 download site. Follow the download and installation instructions on the Microsoft page. If the link is broken, please let us know by email. Note that this MASM download only works with Visual C++ 2005 Express. MASM 8.0 is almost identical to MASM 9.0.

Next: Install the Example Programs

The latest copy of the example programs are listed below.

Example programs and link libraries (designed for Visual Studio 2008) New

Example programs and link libraries (designed for Visual Studio 2005)

The examples are stored in a self-extracting archive file that automatically extracts to the c:\Irvine folder. Unless you have some objection to using that location, do not alter the path. (Lab managers: you can designate c:\Irvine directory as read-only.) If you plan to change the installation location, read our instructions relating to changing project properties.

The folllowing files will be copied into the c:\Irvine directory:

Filename	Description
GraphWin.inc	Include file for writing Windows applications
Irvine16.inc	Include file used with the Irvine16 link library (16-bit applications)
Irvine16.lib	16-bit link function library used with this book
Irvine32.inc	Include file used with the Irvine32 link library (32-bit applications)
Link16.exe	16-bit linker
Irvine32.lib	32-bit link function library used with this book
Macros.inc	Include file containing macros (explained in Chapter 10)
SmallWin.inc	Small-sized include file, used by Irvine32.inc
make16.bat	Batch file for building 16-bit applications
VirtualKeys.inc	Keyboard code definitions file, used by Irvine32.inc

A subdirectory named Examples will contain all the example programs shown in the book.

Building a Sample Assembly Language Program

Preliminary Step: Set Tab Size to 5

Start Visual C++ Express, and select Options from the Tools menu. Select Text Editor, Select All Languages, and select Tabs:

Set the Tab Size and Indent Size to 5.

Opening a Project

Visual Studio and Visual C++ Express require assembly language source files to belong to a project, which is a kind of container. A project holds configuration information such as the locations of the assembler, linker, and required libraries. A project has its own folder, and it holds the names and locations of all files belonging to it. We have created a sample project folder in the c:\Irvine\Examples directory, and its name is Project_Sample.

Do the following steps, in order:

1. Start Visual Studio or Visual C++ Express.
2. If you're using Visual Studio, select Open Project from the File menu. Or, if you're using Visual C++ Express, select Open, and select Project/Solution.
3. Navigate to the c:\Irvine\Examples\Project_Sample folder and open the file named Project.sln.
4. In the Solution Explorer window, click the + symbol next to the item named Project to expand it. Double-click the file named main.asm to open it in the editing window. (Visual Studio users may see a popup dialog asking for the encoding method used in the asm file. just click the OK button to continue.)

Tip: If the Solution Explorer window is not visible, select Solution Explorer from the View menu. Also, if you do not see main.asm in the Solution Explorer window, look at the tabs along the bottom of the window. Click the Solution Explorer tab.

You should see the following program in the editor window:

TITLE MASM Template (main.asm) ; Description: ; ; Revision date: INCLUDE Irvine32.inc .data myMessage BYTE "MASM program example",0dh,0ah,0 .code main PROC call Clrscr mov edx,OFFSET myMessage call WriteString exit main ENDP END main

Later, we'll show you how to copy this program and use it as a starting point to write your own programs.

Build the Program

Next, you will build (assemble and link) the sample program:

• If you're using Visual C++ Express, select Build Solution from the Build menu.
• If you're using Visual Studio, select Build Project from the Build menu.

In the output window at the bottom of the screen, you should see messages similar to the following, indicating the build progress:

1>------ Build started: Project: Project, Configuration: Debug Win32 ------ 1>Assembling... 1>Assembling: .\main.asm 1>Linking... 1>Embedding manifest... 1>Build log was saved at "file://g:\masm\Project_sample\Debug\BuildLog.htm" 1>Project - 0 error(s), 0 warning(s) ========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========

If you do not see these messages, the project has probably not been modified since it was last built. No problem--just add a space somewhere in the document, save it, and try the Build command again.

Run the Program

Select Start without Debugging from the Debug menu. The following console window should appear, although your window will be larger than the one shown here:

The "Press any key to continue..." message is automatically generated by Visual C++ Express.

Congratulations, you have just run your first Assembly Language program.

Press any key to close the Console window.

When you assembled and linked the project, a file named Project.exe was created inside the project's \Debug folder. This is the file that executes when you run the project. You can execute Project.exe by double-clicking its name inside Windows Explorer, but it will just flash on the screen and disappear. That is because Windows Explorer does not pause the display before closing the command window.

Creating New Projects of Your Own

Before long, you will want to create your own projects. The easiest way to do this is to copy the entire c:\Irvine\Examples\Project_Sample folder to a new location. Copy it to a folder in which you have read/write permissions. (If you're working in a college computer lab, a useful location is a portable USB drive. Then you can modify the program, build, and run it again.

Step 5: Running the Sample Program in Debug Mode

In this step, you will set a breakpoint inside the sample program. Then you will use the Visual C++ debugger to step through the program's execution one statement at a time.

1. To begin stepping through your program in Debug mode, press the F10 key.
2. A yellow arrow will appear next to the first program statement (call Clrscr).The arrow indicates that the statement is next to be executed.
3. Press the F10 key (called Step Over) to execute the current statement. Continue pressing F10 until the program is about to execute the exit statement.
4. A small black window icon should appear on your Windows status bar. Open it and look at the contents of the Command window. You should see the words "MASM program example" in the window.
5. Press F10 one more time to end the program.

Registers

If you want to display the CPU registers, do the following: Start debugging the program, then select Windows from the Debug menu. Select Registers from the drop-down list. The bottom window will display the register contents. Right click this window and check the item Flags to enable the display of conditional flags.

You can interrupt a debugging session at any time by selecting Stop Debugging from the Debug menu. You can do the same by clicking the blue square button on the toolbar. To remove a breakpoint from the program, click on the red dot so that it disappears.

Setting a BreakPoint

If you set a breakpoint in a program, you can use the debugger to execute the program a full speed (more or less) until it reaches the breakpoint. At that point, the debugger drops into single-step mode.

1. Click the mouse along the border to the left of the call WriteString statement. A large red dot should appear in the margin.
2. Select Start Debugging from the Debug menu. The program should run, and pause on the line with the breakpoint, showing the same Yellow arrow as before.
3. Press F10 until the program finishes.

You can remove a breakpoint by clicking its red dot with the mouse. Take a few minutes to experiment with the Debug menu commands. Set more breakpoints and run the program again. For the time being, you can use the F11 key to step through the program in the same way the F10 key did.

Building and Running Other Programs

Suppose you want to run another example program, or possibly create your own program. You can either edit and modify main.asm, or you can remove main.asm from the project and insert some other .asm file into the project.

• To remove a program from a project without deleting the file, right-click its name in the Solution Explorer window. In the context menu, select Exclude from Project. If you change your mind and decide to add it back to the project, right-click in the same window, select Add, select Existing item, and select the file you want to add.
• To remove a program from a project and delete the source code file, select the file with the mouse and press the Del key. Or, you can right-click the file name and select Remove.

Adding a File to a Project

The easiest way to add an assembly language source file to an open project is to drag its filename with the mouse from a Windows Explorer window onto the name of your project in the Solution Explorer window. A reference to the file (not a copy) will be inserted in your project's directory. Try this now:

1. Remove the main.asm file from your project.
2. Add a reference to the file c:\Irvine\Examples\ch03\AddSub.asm to the project.
3. Build and run the project.

Here is what you should see in the Console window, except that only your EAX register will have the same value as ours:

When you press a key, the console window will close.

Copying a source file

If you want to make a copy of an existing file, use Windows Explorer to copy the file into your project directory. Then, right-click the project name in Solution Explorer, select Add, select Existing Item, and select the filename.