JAL Computing

Getting Started

Here is a quick start in IL .NET.

Using the Tools

If you have Visual Studio .NET 2003, the CIL assembler (ilasm.exe) is available at C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322

The CIL dis-assembler (ildasm.exe) is available at
C:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\Bin

You can launch these tools from the command line by adding these two paths to your system path. Under Windows XP go to Start--> Settings --> Control Panel --> System --> Advanced -> Environmental Variables --> System Variables --> Path and click on Edit.

Once you have the Path variable set appropriately you can launch the GUI dis-assembler from the command line as:

>ildasm <NameOfManagedCodeBinaryApplication>.exe

You can also compile IL assembler code into virtual machine binary code from the command line by navigating to the folder containing the source code and entering:

>ilasm <NameOfILAssemblerFile>.il

ildasm

Here is the GUI view of a Hello World program opened in the dis-assembler.

The dis-assembler converts the virtual machine binary code into low level human readable IL assembler code. Here is the Manifest IL for the Hello World application.

.assembly extern mscorlib
{
  .ver 0:0:0:0
}
.assembly HelloWorld
{
  .ver 1:0:1:0
}
.module HelloWorld.exe
// MVID: {4D86A6B8-B03E-4FE4-AF79-93F4330CED98}
.imagebase 0x00400000
.subsystem 0x00000003
.file alignment 512
.corflags 0x00000001
// Image base: 0x06c00000

Here is the IL for Main:

.method privatescope static void  Main$PST06000001() cil managed
{
  .entrypoint
  // Code size       21 (0x15)
  .maxstack  2
  IL_0000:  ldstr      "Hello World!"
  IL_0005:  ldstr      "JAL 11.24.04"
  IL_000a:  call       void [mscorlib]System.Console::WriteLine(string)
  IL_000f:  call       void [mscorlib]System.Console::WriteLine(string)
  IL_0014:  ret
} // end of method 'Global Functions'::Main

The program sets the stack size to two. It then pushes two strings onto the stack and outputs them to the console using System.Console.WriteLine. Each call to WriteLine pops a string off the stack leaving an empty stack (void) on return.

Here is the program output:

Hello World!
JAL 11.24.04

ilasm

You can write managed code in low level IL assembler rather than using a high level language such as C#. You can use Notebook as your editor and rename the saved file using the .il extension. Here is the IL assembler source code for our Hello World application.

// HelloWorld.il
// Test IL Assembler
// 11.24.04 Jeff Louie

.assembly extern mscorlib {}
.assembly HelloWorld {.ver 1:0:1:0}
.module HelloWorld.exe
.method static void Main() cil managed
{
	.maxstack 2
	.entrypoint

	ldstr "Hello World!"
	ldstr "JAL 11.24.04"
	call void [mscorlib]System.Console::WriteLine(string)
	call void [mscorlib]System.Console::WriteLine(string)
	ret
}

Learn More

If you want to learn more about the CIL check out these links.

	http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnhcvs03/html/vs03k1.asp
	http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cptutorials/html/il_dasm_tutorial.asp

There is also extensive documentation in the SDK at C: --> Program Files --> Microsoft Visual Studio .NET 2003 --> SDK --> v1.1 --> Tool Developers Guide --> Docs --> Partition III CIL.

Have fun,
Jeff

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