Author Topic: Nasm to Goasm  (Read 388 times)

bartc

  • Regular Member
  • *
  • Posts: 8
Nasm to Goasm
« on: April 29, 2017, 06:09:33 AM »
I've been using Nasm as a compiler target for years, but now want to try Goasm.

Is there a summary somewhere of the differences in syntax?

(And, more importantly, do I have to research a bunch of history facts every time I post?!)

bartc

  • Regular Member
  • *
  • Posts: 8
Re: Nasm to Goasm
« Reply #1 on: April 29, 2017, 08:49:35 PM »
In the absence of just a simple list of how to do labels, memory accesses, imports, exports etc, I'm just trying trial and error. I tried this program:

Code: [Select]
CODE SECTION
main:

sub RSP,8
sub RSP,32
mov RCX,addr KK1
call puts
add RSP,32
mov EAX,0
sub RSP,32
call exit

DATA SECTION

;string table:
KK1: db 'Hello World!',10,0

It was compiled with:

    goasm /x64 hello.asm64

And linked with:

    golink /entry main hello.obj \windows\system32\msvcrt.dll

It produces a 2KB file hello.exe which runs, but doesn't show any output. Anyone know what's wrong my the code?

Also, I understand that the label KK1 is automatically exported, so might clash with the same label used in another module. How to define a label that is local to this file?

Thanks.

TWell

  • Member
  • ****
  • Posts: 748
Re: Nasm to Goasm
« Reply #2 on: April 29, 2017, 10:52:49 PM »
missing option /console

jj2007

  • Member
  • *****
  • Posts: 7470
  • Assembler is fun ;-)
    • MasmBasic
Re: Nasm to Goasm
« Reply #3 on: April 29, 2017, 11:18:52 PM »
In the absence of just a simple list of how to do labels, memory accesses, imports, exports etc, I'm just trying trial and error.

If you chose "plain" Masm instead of GoAsm, you would find plenty of material in \Masm32\examples
Here is one:
Code: [Select]
include \masm32\include\masm32rt.inc ; plain Masm32 for the fans of pure assembler

.code
AppName db "Masm32:", 0

start: MsgBox 0, "Hello World", addr AppName, MB_OK
exit

end start

Check also What you absolutely need to get started. And maybe you could post a few explanations what you intend to do.

Re code not showing output, Nidud told you already about the linker option. Some simpler editors do not autodetect the subsystem, so you need to set it manually, e.g. via a menu "build as console app" or similar.

shankle

  • Member
  • ****
  • Posts: 748
Re: Nasm to Goasm
« Reply #4 on: April 30, 2017, 12:59:39 AM »
My 2 cents worth-----
Are you using the 32 bit or 64-bit compiler?
It does make a difference.

wjr

  • Member
  • **
  • Posts: 185
    • WJR's website
Re: Nasm to Goasm
« Reply #5 on: April 30, 2017, 02:48:09 AM »
In the GoAsm Manual index under "adapting files for GoAsm" you will see a list of the changes that the tool AdaptAsm can do, and another list with details on the remaining items to check or convert.

As for local labels, there are various methods for local code labels and stack based data labels, but correct, for DATA and CONST labels, these symbols will be available for external use.

However, for the example that you used, the KK1 label is used for a string that may only get used once. For something like this, if you used INVOKE with the actual string as a parameter, GoAsm will put the null terminated string in the CONST section if there is one (or DATA, or lastly CODE) and take care of passing the proper address to this string.

bartc

  • Regular Member
  • *
  • Posts: 8
Re: Nasm to Goasm
« Reply #6 on: April 30, 2017, 05:17:45 AM »
missing option /console
That did the trick, thanks.

But a problem has come up which I can't explain. If I create a new program hello.asm64 (generated from my compiler) like this:
...
And actually, while trying to paste the code, I've think I've just seen the cause. The compiler generates asm code with LF line endings only. GoAsm doesn't like it, but it just says this:

 Error!
 No code or data found in assembler source file
 OBJ file not made

If I made any change with my text editor, even nothing at all, just saving the same text, it would appear to fix it. But my editor writes CRLF. GoAsm doesn't mind CR only, but then my editor doesn't like it! So it'll have to be CR,LF.