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After I compile this (MASM32,CONSOLE), I get the Windows screen "bla.exe encountered a problem and needs to close. We are...". Does anyone see anything wrong with this. It should output "a" character to console.
Code:.386
.model flat,stdcall
.CODE
start:
mov dl, 97
mov ah, 2h
int 21h
ret
end start
That code worked in DOS. It does nothing in Win32 executables, except trigger the OS's "bad program" alarms.
Well, I'd like to do it in console...
Can I do it with interrupts?
No. You can do it by calling into the C runtime or the Win32 API. WriteConsole exists, I think, or if not, use GetStdHandle to obtain the stdout handle and use any file write API to write to it.
You can of course call the win32 API from asm just as easily as you can from C or C++
I know that, I just wondered if it is possible to do it without API calls.
Call the C runtime. Of course, it will only internally call the API in turn.
Nothing in Windows is possible without API calls if it has to interact with the system in any way. That's the point: the API is the way you interact with the system.
Aren't there ANY working interrupts in Windows?
I've heard Native API can be accessed through interrupts and I found an example of NtQuerySystemInformation:
Code:NtQuerySystemInformation:
mov eax, 97h
lea edx, [esp+4]
int 2Eh
ret 10h
Now I came up with this, it should convert a string to uppercase:
It only does it to the last character of the string.Code:EditAddr proc theaddr:DWORD
mov edx,theaddr
mydock:
mov ax,0
cmp [edx],ax
je theend
mov ax,97
cmp [edx],ax
jl runagain
mov ax,122
cmp [edx],ax
jg runagain
mov ax,32
sub [edx],ax
runagain:
inc edx
jmp mydock
theend:
ret
EditAddr endp
Why would you possibly want to do this? I mean, yes, it's probably possible: the fastest way to switch between kernel and user mode on the IA-32 architecture is a software interrupt, so internally, the API probably uses them. But why you, as the end user?
Yeah, I know it's silly, but I just wondered if there are any interrupts still used under Windows.
Now I know there are some, and that's enough for me :D
The problem with my function was that ax register is 16bit and it takes 2 characters together to ax and if the 2nd character is not NULL then it is always over 122. I needed to use ah register instead.
The whole 'no interrupts' has to do with how Intel designed the x86 architecture under protected mode. To understand why there are 'no' interrupts I suggest you read the tech refs provided on their site.
If you insist on doing this from pure asm, then Salem's suggestion will work. Just make sure you know the exact prototype and call method for the function or you will not get what you want. Most of the API is declared as PASCAL which pushes the parameters onto the stack totally reverse of what you are used to.
Yeah I know, I've been using Win32 API in assembly.
Quote:
I know that, I just wondered if it is possible to do it without API calls.
Well seems to me since you know so much you don't need our help eh?Quote:
Yeah I know, I've been using Win32 API in assembly.
"that" is what I already knew, the second part means what I didn't know before :)Quote:
I know that, I just wondered if it is possible to do it without API calls.