Tag: r

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0 answers
58 views
No artigo de hoje vou apresentar a você 15 dicas muito boas da linguagem

   Atenção: nem todas dicas, especialmente os atalhos de código, v&at

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asked 14 June, 2023
0 votes
0 answers
69 views
1 votes
0 answers
213 views
Hello i am interested :)

Hello i am interested :)  Hello i am interested :) Hello i am interested :) Hello i am int

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Alfred Marku
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asked 21 October, 2021
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

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Kisha
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asked 07 September, 2021
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

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Winford
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asked 07 September, 2021
50 votes
4 answers
831 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

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Royal
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asked 07 September, 2021
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

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Sydney
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asked 07 September, 2021
60 votes
3 answers
2.8K views
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'

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Vi
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asked 07 September, 2021
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

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Kisha
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asked 07 September, 2021
53 votes
1 answers
1K views
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

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User demo
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asked 07 September, 2021
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

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Robyn
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asked 07 September, 2021
63 votes
4 answers
977 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

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Frederick
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asked 07 September, 2021
52 votes
1 answers
560 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

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Majorie
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asked 07 September, 2021
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,

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Juliane
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asked 07 September, 2021
66 votes
13 answers
1.7K views
Can num++ be atomic for 'int num'?

In general, for int num, num++ (or ++num), as a read-modify-write operation, is not atomic. But I often see co

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Forrest
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asked 07 September, 2021
50 votes
3 answers
1.8K views
Why does GCC generate such radically different assembly for nearly the same C code?

While writing an optimized ftol function I found some very odd behaviour in GCC 4.6.1. Let me show you the cod

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Eddie
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asked 07 September, 2021
64 votes
21 answers
383 views
Is inline assembly language slower than native C++ code?

I tried to compare the performance of inline assembly language and C++ code, so I wrote a function that add tw

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Rudolf
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asked 07 September, 2021
56 votes
4 answers
3K views
Why would introducing useless MOV instructions speed up a tight loop in x86_64 assembly?

Background: While optimizing some Pascal code with embedded assembly language, I noticed an unnecessary MOV i

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Jesenia
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asked 07 September, 2021
62 votes
5 answers
2.5K views
Why does GCC use multiplication by a strange number in implementing integer division?

I've been reading about div and mul assembly operations, and I decided to see them in action by writing a

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Xavier
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asked 07 September, 2021