.386
.model flat, c
.stack 100 h
.data
num1 sdword ?
num2 sdword ?
.code
main proc
mov num1,5
mov eax,num1
mov num2,eax
ret
main endp
end
I have checked the masm in the build customization of the project.
I have changed the item type to Microsoft Macro Assembler.
But, it is still showing error messages below:
Severity Code Description Project File Line Suppression State
Error A2206 missing operator in expression testing C:\Users\Kin\Desktop\assembly\testing\testing\Source.asm 3
Error A2206 missing operator in expression testing C:\Users\Kin\Desktop\assembly\testing\testing\Source.asm 2
Error MSB3721 The command "ml.exe /c /nologo /Zi /Fo"Debug\Source.obj" /W3 /errorReport:prompt /TaSource.asm" exited with code 1. testing H:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\VC\VCTargets\BuildCustomizations\masm.targets 50
Changed to .stack 100h
It is now showing:
Severity Code Description Project File Line Suppression State
Error LNK1120 1 unresolved externals testing C:\Users\Kin\Desktop\assembly\testing\Debug\testing.exe 1
Error LNK2001 unresolved external symbol _WinMainCRTStartup testing C:\Users\Kin\Desktop\assembly\testing\testing\LINK 1
Related
I am new to assembly and I am trying to build my code. But when ever I try, I get this error that I don't understand:
Severity Code Description Project File Line Suppression State
Error MSB3721 The command "ml.exe /c /nologo /Zi /Fo"Debug\Main.obj" /W3 /errorReport:prompt /TaMain.asm" exited with code 1. TestProject D:\VS\vs\MSBuild\Microsoft\VC\v170\BuildCustomizations\masm.targets 70
This file is not even in my project, I think it is the compiler but I am not sure why it is giving this error. Here is my code:
.386
.model flat
.code
start PROC
mov eax, 213
add eax, 432
ret
start endp
end start
I am using the VS masm and Local Windows Debuger. The version is 2022 comunity. If anyone knows the solution, or if I need to add more details please tell me.
Thank you and have a nice day!
I'm trying to run an assembly program using MASM in Visual Studio. This is the code I have
include Irvine32.inc
.data
str1 BYTE "a test string",0
.code
main proc
mov edx,OFFSET str1
call WriteString
exit
main endp
End main
The error I'm getting is:
error LNK2019: unresolved external symbol _WriteString#0 referenced in function _main#0"
Why am I getting this error?
Press Shift + Alt + A
find Irvine32.inc and Irvine32.lib from your HDD
Add them in your project repository.
The linker error suggests that you aren't linking against the Irvine32 library. Although you have included Irvine32.inc at the top of your assembly program, you still need to add Irvine32.lib as a library to link against in your Solution, or add it to your command line (if compiling with at a command shell), or use includelib directive inside your assembly code to link with it.
.386
.model flat,stdcall
.stack 4096
ExitProcess proto,dwExitCode:dword
DumpRegs PROTO
.code
main proc
mov cx, 01h
sub cx, 2
call DumpRegs
add cx, 2 ; Clears the sign flag
invoke ExitProcess,0
main endp
end main
Errors:
1>Example.obj : warning LNK4258: directive '/ENTRY:main#0' not compatible with switch '/ENTRY:main'; ignored
1>Example.obj : error LNK2019: unresolved external symbol _DumpRegs#0 referenced in function _main#0
1>C:...: fatal error LNK1120: 1 unresolved externals
I tried looking up how to resolve this issue but have had no luck. Can anyone help me get this thing running?
SOLUTION: For those using Kip Irvine's book and trying to get their stuff to work, you can find how to create a project from scratch using the libraries in his book here (bottom): http://kipirvine.com/asm/gettingStartedVS2013/index.htm
Note that it is below his first two entrys on how to create a program which makes it somewhat difficult to find.
you need to include the library that has the dumpregs process using INCLUDE and INCLUDELIB.
I'm trying to run the following Hello Word example in x86 assembly under Windows:
global _main
extern _GetStdHandle#4
extern _WriteFile#20
extern _ExitProcess#4
section.text
_main :
; DWORD bytes;
mov ebp, esp
sub esp, 4
; hStdOut = GetstdHandle(STD_OUTPUT_HANDLE)
push - 11
call _GetStdHandle#4
mov ebx, eax
; WriteFile(hstdOut, message, length(message), &bytes, 0);
push 0
lea eax, [ebp - 4]
push eax
push(message_end - message)
push message
push ebx
call _WriteFile#20
; ExitProcess(0)
push 0
call _ExitProcess#4
; never here
hlt
message :
db 'Hello, World', 10
message_end :
But then I get the following error when trying to link the assembled .obj file:
error LNK2001: unresolved external symbol _GetStdHandle#4
error LNK2001: unresolved external symbol _WriteFile#20
error LNK2001: unresolved external symbol _ExitProcess#4
fatal error LNK1120: 3 unresolved externals
Source of my example: How to write hello world in assembler under Windows?
How to fix these? Or also, why isn't the example working for me?
When using a C compiler the standard libraries are typically linked to the code which is typically not done when calling the linker separately.
The three functions are located in "kernel32.dll" so you'll have to link against "kernel32.lib" (or "libkernel32.a" when using GNU tools).
Your entry point is "_main" so I assume you want to use the startup object files, too.
However this is not neccessary in your case so you may simply define "_main" as linker entry point and not link against the startup object files.
I am trying to create a helloworld program using only masm and not masm32 libs. Here is the code snippet:
.386
.model flat, stdcall
option casemap :none
extrn MessageBox : PROC
extrn ExitProcess : PROC
.data
HelloWorld db "Hello There!", 0
.code
start:
lea eax, HelloWorld
mov ebx, 0
push ebx
push eax
push eax
push ebx
call MessageBox
push ebx
call ExitProcess
end start
I am able to assemble this using masm:
c:\masm32\code>ml /c /coff demo.asm
Microsoft (R) Macro Assembler Version 9.00.21022.08
Copyright (C) Microsoft Corporation. All rights reserved.
Assembling: demo.asm
However, I am unable to link it:
c:\masm32\code>link /subsystem:windows /defaultlib:kernel32.lib /defaultlib:user
32.lib demo.obj
Microsoft (R) Incremental Linker Version 9.00.21022.08
Copyright (C) Microsoft Corporation. All rights reserved.
demo.obj : error LNK2001: unresolved external symbol _MessageBox
demo.obj : error LNK2001: unresolved external symbol _ExitProcess
demo.exe : fatal error LNK1120: 2 unresolved externals
I am including the libs during linking, so not sure why it still says unresolved symbols?
UPDATE:
c:\masm32\code>link /subsystem:windows /defaultlib:kernel32.lib /defaultlib:user
32.lib demo.obj
Microsoft (R) Incremental Linker Version 9.00.21022.08
Copyright (C) Microsoft Corporation. All rights reserved.
demo.obj : error LNK2001: unresolved external symbol _MessageBox#16
demo.exe : fatal error LNK1120: 1 unresolved externals
UPDATE 2: Final working code!
.386
.model flat, stdcall
option casemap :none
extrn MessageBoxA#16 : PROC
extrn ExitProcess#4 : PROC
.data
HelloWorld db "Hello There!", 0
.code
start:
lea eax, HelloWorld
mov ebx, 0
push ebx
push eax
push eax
push ebx
call MessageBoxA#16
push ebx
call ExitProcess#4
end start
The correct function names are MessageBoxA#16 and ExitProcess#4.
Almost all Win32 API functions are stdcall, so their names are decorated with an # sign, followed by the number of bytes taken up by their parameters.
Additionally, when a Win32 function takes a string, there are two variants: one that takes an ANSI string (name ends in A) and one that takes a Unicode string (name ends in W). You're supplying an ANSI string, so you want the A version.
When you're not programming in assembly the compiler takes care of these points for you.
Try adding this before .data segment:
include \masm32\include\kernel32.inc
include \masm32\include\user32.inc
includelib \masm32\lib\kernel32.lib
includelib \masm32\lib\user32.lib