windows - Compiling assembly in Visual Studio

Question

How do you compile assembly code using Visual Studio?

I want to compile and run an assembly source file in Visual Studio 2010.

I've created a Visual C++ project and inserted some assembly code in a file code.asm:

.586              ;Target processor.  Use instructions for Pentium class machines
.MODEL FLAT, C    ;Use the flat memory model. Use C calling conventions
.STACK            ;Define a stack segment of 1KB (Not required for this example)
.DATA             ;Create a near data segment.  Local variables are declared after
                  ;this directive (Not required for this example)
.CODE             ;Indicates the start of a code segment.

clear PROC
   xor eax, eax 
   xor ebx, ebx 
   ret 
clear ENDP 
END

However the problem is when you try and compile this, you get:

LINK : error LNK2001: unresolved external symbol _mainCRTStartup

I did go and enable the build customization masm.targets (right click project > Build Customizations..), but to no avail.

Answer 1

Sounds to me like the custom build rules for .asm files isn't enabled. Right-click the project, Custom Build Rules, tick "Microsoft Macro Assembler". With the "END clear" directive and disabling incremental linking I'm getting a clean build.

It's different starting from VS2010:

1. Right-click Project, Build customizations, tick "masm".
2. Right-click the .asm file, Properties, change Item Type to "Microsoft Macro Assembler".