Recent questions tagged Assembly

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assembly - Binary Bomb Phase 5 - lookup table translation -> string compare

I have been working on a Binary Bomb for school, and I am absolutely lost in Phase 5. The object of the ... >: ret End of assembler dump. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Linux x64: why does r10 come before r8 and r9 in syscalls?

I decided to take a crack at assembly the other day, and I've been playing around with really basic things like ... then why was it swapped in? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Can PTEST be used to test if two registers are both zero or some other condition?

What can you do with SSE4.1 ptest other than testing if a single register is all-zero? Can you use a ... not both zero without destroying them See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Initial state of program registers and stack on Linux ARM

I'm currently playing with ARM assembly on Linux as a learning exercise. I'm using 'bare' assembly, i.e ... ? Any pointers would be appreciated. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Why is it not possible to push a byte onto a stack on Pentium IA-32?

I've come to learn that you cannot push a byte directly onto the Intel Pentium's stack, can anyone explain this ... my naivety in any of this. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Fast Division on GCC/ARM

As far as I know most compilers will do fast division by multiplying and then bit shifting to the right. For ... result in memory (from r3) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Does Java strictfp modifier have any effect on modern CPUs?

I know the meaning of the strictfp modifier on methods (and on classes), according to the JLS: JLS 8.4 ... and without the strictfp modifier? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is the penalty of mixing EVEX and VEX encoded scheme?

It is a known issue that mixing VEX-encoded instructions and non-VEX instructions has a penalty and the programmer must ... we want to mix them. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - How is floating point conversion actually done in C++?(double to float or float to double)

So I've searched about this topic and found nothing really relevant about it. I've tried to look at the ... the actual operations performed... See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Convert ASM to C (not reverse engineer)

I googled and I see a surprising amount of flippant responses basically laughing at the asker for asking such a ... surely can be translated. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - How many ways to set a register to zero?

I'm curious how many ways are there to set a register to zero in x86 assembly. Using one instruction. Someone told me ... mov ax, 0 and ax, 0 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What are the ESP and the EBP registers?

I found that the ESP register is the current stack pointer and EBP is the base pointer for the current stack ... like most ISAs) grows downward. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is the point of delay slots?

So from my understanding of delay slots, they occur when a branch instruction is called and the next ... getting carried out anyway.. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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676 views

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assembly - more info on Memory layout of an executable program (process)

I attended interview for samsung. They asked lot of questions on memory layout of the program. I barely know anything ... me look so stupid. :) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Difference between JE/JNE and JZ/JNZ

In x86 assembly code, are JE and JNE exactly the same as JZ and JNZ? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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964 views

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assembly - 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 ... Can someone also give an example? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.4k views

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assembly - Printing floats with printf in x86 nasm 32-bit

I'm trying to print out some 32-bit floats using NASM flavored x86 assembly. This is a minimum working ... have to be missing something. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is the point of SSE2 instructions such as orpd?

The orpd instruction is a "bitwise logical OR of packed double precision floating point values". Doesn't this do ... the point of having it? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Binary Bomb Phase 5 issue (my phase 5 seems to be different from everyone elses)

So I am working on a Binary Bomb assignment and have gotten stuck. Tried looking at other questions and guides ... if my formatting is wrong. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - BIOS int 10h printing garbage on QEMU

I have a problem while writing an x86 real mode assembly program that runs as a bootloader in QEMU. I'm trying to ... and how can it be fixed? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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781 views

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assembly - How much faster are SSE4.2 string instructions than SSE2 for memcmp?

Here is my code's assembler Can you embed it in c ++ and check against SSE4? At speed I would ... 32bit https://vk.com/doc297044195_451679410 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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880 views

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assembly - When should I use size directives in x86?

When to use size directives in x86 seems a bit ambiguous. This x86 assembly guide says the following: In ... the DWORD PTR directive redundant? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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934 views

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assembly - Why can I access lower dword/word/byte in a register but not higher?

I started to learn assembler, and this does not looks logical to me. Why can't I use multiple higher bytes ... and forget about the lower parts? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Using ymm registers as a "memory-like" storage location

Consider the following loop in x86: ; on entry, rdi has the number of iterations .top: ; some magic ... consider solutions that use them. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Which versions of Windows support/require which CPU multimedia extensions? (How to check if SSE or AVX are fully usable?)

So far I have managed to find out that: SSE and SSE2 are mandatory for Windows 8 and later (and of course for ... from one of the SSE/AVX sets. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

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assembly - Differences between general purpose registers in 8086: [bx] works, [cx] doesn't?

In 8086 this structure is correct: mov bh,[bx] but this is not correct: mov bh,[cx] I don't know why. ... save the base address in cx register?) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.2k views

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assembly - Getting string input and displaying input with DOS interrupts MASM

In MASM, I created a buffer variable to hold the user string input from keyboard. I am stuck on how to ... of input of buffered characters. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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813 views

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assembly - How to determine if the registers are loaded right to left or vice versa

When reviewing gdb output and looking at the assembly calls, usually I can find a command using hard-coded values ... to right or vice versa? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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