I have the following function in assembly, but I need it in C. The code is:
push ebp
mov ebp, esp
mov eax, DWORD PTR [ebp+8]
add eax, 1667940388
pop ebp
ret
Could anybody translate this into C for me. Thanks.
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5homework? what did you do so far?Jason Hu– Jason Hu2014-10-01 17:57:02 +00:00Commented Oct 1, 2014 at 17:57
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I literally don't know assembly thats why I'm asking. Trying to learn as I go but its for intro CTF. Just want to make sure I'm on the right track understanding everything.Spitfire– Spitfire2014-10-01 17:57:11 +00:00Commented Oct 1, 2014 at 17:57
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1Then post what you think it means, we can help you understand if you're on the right track.Cory Nelson– Cory Nelson2014-10-01 17:57:39 +00:00Commented Oct 1, 2014 at 17:57
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@DaleLakes take a look at CSAPP. it tells a lot.Jason Hu– Jason Hu2014-10-01 17:59:27 +00:00Commented Oct 1, 2014 at 17:59
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So far I know eax is a 32-bit integer representation of ebp (I think). Then you add that number and eax together. What gets returned though?Spitfire– Spitfire2014-10-01 18:01:09 +00:00Commented Oct 1, 2014 at 18:01
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1 Answer
Sorry for the silly mistake on the eax return value ... its' fixed now ... my assembly is a little rusty :)
int function(int value)
{
return value + 1667940388;
}
6 Comments
isedev
it actually returns the value (in eax)
Jason Hu
it's not correct.
eax is return register. it return a value.
Spitfire
Ok that's what I was thinking. What does the ebp+8 do? Thats the only part I don't get.
isedev
The function's argument was pushed on the stack by the caller, then the function's return address. The function then pushes
ebp on the stack then sets ebp to the current stack pointer. By that point, ebp+8 points to the function's argument (ebp+0 is the saved ebp value, ebp+4 is the return address) - this being 32-bit code of course.Spitfire
Ok. So if I have 2 variables in the function's argument, then ebp+8 would be the first argument and ebp+12 would be the second?
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