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Assembly wierdness
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I am doing Narue's Introduction to Assembly, and when I run my program, nothing happens.
This is my code:
This is what happened in my command window:
Any help would be appreciated
This is my code:
asm Syntax (Toggle Plain Text)
Assembly Syntax (Toggle Plain Text)
Any help would be appreciated
Last edited by tomtetlaw; Aug 16th, 2009 at 4:04 am.
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Practically a Posting Shark
MASM is my thing when linked with Visual Studio. Not NASM but I'll try to help...
Assemble First.asm into an Win32 object file First.obj
C:\Documents and Settings\tom\Desktop\Assembly>nasm -f win32 First.asm -o First.obj
Seems okay
C:\Documents and Settings\tom\Desktop\Assembly>gcc First.obj -o prog.exe
C:\Documents and Settings\tom\Desktop\Assembly>prog.exe
C:\Documents and Settings\tom\Desktop\Assembly>
Try moving the .data section below the .text (code) section. If the data is put into the code segment then the code is being displaced and the data is being treated as code. Dumping lst output or memory map would give more clues!
In masm one would define
end Start
at the end of the file to indicate where the code is to start. As the concept of 'main' is a C/C++ thing, not assembly language! It merely starts at the beginning of the code segment unless overwritten like with the end Main as indicated!
Looking at the NASM documentation, it appears you need to insert a declaration.
So the code knows where to begin execution!
Assemble First.asm into an Win32 object file First.obj
C:\Documents and Settings\tom\Desktop\Assembly>nasm -f win32 First.asm -o First.obj
Seems okay
C:\Documents and Settings\tom\Desktop\Assembly>gcc First.obj -o prog.exe
C:\Documents and Settings\tom\Desktop\Assembly>prog.exe
C:\Documents and Settings\tom\Desktop\Assembly>
Try moving the .data section below the .text (code) section. If the data is put into the code segment then the code is being displaced and the data is being treated as code. Dumping lst output or memory map would give more clues!
In masm one would define
end Start
at the end of the file to indicate where the code is to start. As the concept of 'main' is a C/C++ thing, not assembly language! It merely starts at the beginning of the code segment unless overwritten like with the end Main as indicated!
Looking at the NASM documentation, it appears you need to insert a declaration.
Assembly Syntax (Toggle Plain Text)
Last edited by wildgoose; Aug 17th, 2009 at 4:42 am.
This is now my code:
_read DOES get input from the user and store it in eax right?
This is what happens when I run the thing:
help?
asm Syntax (Toggle Plain Text)
_read DOES get input from the user and store it in eax right?
This is what happens when I run the thing:
Assembly Syntax (Toggle Plain Text)
help?
Last edited by tomtetlaw; Aug 17th, 2009 at 7:24 am.
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ok, sorry, here is my code again that still doesn't work:
it doesn't do anything when i run it 
any help?
asm Syntax (Toggle Plain Text)
any help?
Last edited by tomtetlaw; Aug 17th, 2009 at 8:35 am.
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For every push before a call, you have to adjust the stack.
You can't be throwing around code changes and hope it works. You had the code reasonable before. If you're going to make massive changes like that you need to indicate the changes worked, and then why you throwing away what you were helped with.
You can't be throwing around code changes and hope it works. You had the code reasonable before. If you're going to make massive changes like that you need to indicate the changes worked, and then why you throwing away what you were helped with.
Which gcc port are you using? If it is cygwin, then that might be your problem.
Try MingW -- I've always had success with it.
http://www.mingw.org/
Try MingW -- I've always had success with it.
http://www.mingw.org/
while (CPU is present) {some assembly required}
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Join Date: Jun 2009
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Assember is a two pass. If that doesn't work, move all the data in the .data section below the code in the .text section. In these simple configurations typically the Code Segment and Data Segment are shared and having data at the top of your code makes the data appear like opcodes (thus instructions) to the processor and it trys to run the data like code!
When you run it! So that would indicate you get a clean assemble and link and thus you are successful in linking to the libary that contains the print code.
When you run it! So that would indicate you get a clean assemble and link and thus you are successful in linking to the libary that contains the print code.
Last edited by wildgoose; Aug 17th, 2009 at 12:55 pm.
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Originally Posted by wildgoose 
Assember is a two pass. If that doesn't work, move all the data in the .data section below the code in the .text section. In these simple configurations typically the Code Segment and Data Segment are shared and having data at the top of your code makes the data appear like opcodes (thus instructions) to the processor and it trys to run the data like code!
The sections are separated in the object file. The linker may even choose to re-order them when it creates the executable file. The Operating System's loader will likely scatter them into widely-separated areas of memory. In general, the order of .data and .text sections has no effect. The code will start executing at the '_main' label no matter where it appears within the .text section.
However, in a Linux environment, on certain old kernel versions, the order DOES matter. A '.data' section is expected as the last section due to security device implemented by that kernel.
Last edited by Evenbit; Aug 17th, 2009 at 6:46 pm.
while (CPU is present) {some assembly required}
wildgoose -
What you are thinking of is the old '*.com' and '*.exe' formats for DOS which had a segmented memory model. Yes, the '*.com' files were restricted to the SMALL data model which combined all four segments into one -- so the author *did* have to be careful where he place data.
However, modern 32-bit code for modern 32-bit Operating System's do not have support for segments because they all use Virtual Memory.
What you are thinking of is the old '*.com' and '*.exe' formats for DOS which had a segmented memory model. Yes, the '*.com' files were restricted to the SMALL data model which combined all four segments into one -- so the author *did* have to be careful where he place data.
However, modern 32-bit code for modern 32-bit Operating System's do not have support for segments because they all use Virtual Memory.
while (CPU is present) {some assembly required}
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