53
votes
4
answers
1.3K
views
What is the difference between native code, machine code and assembly code?
I'm confused about machine code and native code in the context of .NET languages. What is the difference
51
votes
4
answers
1K
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How can one see content of stack with GDB?
I am new to GDB, so I have some questions: How can I look at content of the stack? Example: to see content of
65
votes
4
answers
1.7K
views
Why does Windows64 use a different calling convention from all other OSes on x86-64?
AMD has an ABI specification that describes the calling convention to use on x86-64. All OSes follow it, excep
55
votes
5
answers
2.9K
views
What is the function of the push / pop instructions used on registers in x86 assembly?
When reading about assembler I often come across people writing that they push a certain register of the proce
61
votes
8
answers
2.3K
views
`testl` eax against eax?
I am trying to understand some assembly. The assembly as follows, I am interested in the testl line: 000319d
50
votes
4
answers
829
views
What are CFI directives in Gnu Assembler (GAS) used for?
There seem to be a .CFI directive after every line and also there are wide varities of these ex.,.cfi_startpro
57
votes
15
answers
1.1K
views
Quickly find whether a value is present in a C array?
I have an embedded application with a time-critical ISR that needs to iterate through an array of size 256 (pr
61
votes
10
answers
681
views
How to view the assembly behind the code using Visual C++?
I was reading another question pertaining the efficiency of two lines of code, and the OP said that he looked
60
votes
3
answers
2.8K
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Possible GCC bug when returning struct from a function
I believe I found a bug in GCC while implementing O'Neill's PCG PRNG. (Initial code on Godbolt'
62
votes
5
answers
1.4K
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Purpose of ESI & EDI registers?
What is the actual purpose and use of the EDI & ESI registers in assembler? I know they are used for stri
51
votes
8
answers
2.3K
views
What is the purpose of XORing a register with itself?
xor eax, eax will always set eax to zero, right? So, why does MSVC++ sometimes put it in my executable
62
votes
3
answers
1.7K
views
What is the meaning of "non temporal" memory accesses in x86
This is a somewhat low-level question. In x86 assembly there are two SSE instructions: MOVDQA xmmi, m128
56
votes
3
answers
2.2K
views
What does `dword ptr` mean?
Could someone explain what this means? (Intel Syntax, x86, Windows) and dword ptr [ebp-4], 0
59
votes
14
answers
2K
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How can I see the assembly code for a C++ program?
How can I see the assembly code for a C++ program? What are the popular tools to do this?
53
votes
1
answers
1K
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What is the best way to set a register to zero in x86 assembly: xor, mov or and?
All the following instructions do the same thing: set %eax to zero. Which way is optimal (requiring fewest mac
49
votes
7
answers
2K
views
How does this milw0rm heap spraying exploit work?
I usually do not have difficulty to read JavaScript code but for this one I can’t figure out the logic. The
63
votes
4
answers
975
views
Why do x86-64 instructions on 32-bit registers zero the upper part of the full 64-bit register?
In the x86-64 Tour of Intel Manuals, I read Perhaps the most surprising fact is that an instruction such a
52
votes
1
answers
558
views
Why do ARM chips have an instruction with Javascript in the name (FJCVTZS)?
FJCVTZS is "Floating-point Javascript Convert to Signed fixed-point, rounding toward Zero". It is supported i
63
votes
12
answers
3K
views
What is the difference between MOV and LEA?
I would like to know what the difference between these instructions is: MOV AX, [TABLE-ADDR] and LEA AX,
65
votes
3
answers
3K
views
How do you use gcc to generate assembly code in Intel syntax?
The gcc -S option will generate assembly code in AT&T syntax, is there a way to generate files in Intel sy
