Recent questions tagged assembly

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assembly - How to completely suspend the processor?

I'm writing a small bootloader for an x86 based PC. The problem is that the CPU is somehow still active after ... 100%. What am I doing wrong? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What does "store-buffer forwarding" mean in the Intel developer's manual?

The Intel 64 and IA-32 Architectures Software Developer's Manual says the following about re-ordering of actions by ... to the same location? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Do x86 instructions require their own encoding as well as all of their arguments to be present in memory at the same time?

I am trying to figure out whether it is possible to run a Linux VM whose RAM is only backed by a single physical ... I am testing on AMD Zen 1. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - x86 NASM 'org' directive meaning

I am following this tutorial as a first foray into bootloader/OS development for x86 using NASM: http:// ... conceptual problem on my part. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - JMP instruction - Hex code

Have a doubt regarding the hex code conversion of JMP machine instruction. I have the absolute address I want to ... , so pardon my ignorance. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is non-aligned access? (ARM/Keil)

I'm using Keil to write Assembly for ARM 7. I have the following runtime error: Non-aligned Access: ARM ... , but it fails here first. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Difference between byte ptr and word ptr

I saw the following question on a test paper, Question VarM DWORD ABBF01598h Give the contents of registers al, ... these. Thanks in advance. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is instruction fusion in contemporary x86 processors?

What I understand is, there are two types of instruction fusions: Micro-operation fusion Macro-operation fusion Micro- ... fusing. Am I correct? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is instruction fusion in contemporary x86 processors?

What I understand is, there are two types of instruction fusions: Micro-operation fusion Macro-operation fusion Micro- ... fusing. Am I correct? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - What is instruction fusion in contemporary x86 processors?

What I understand is, there are two types of instruction fusions: Micro-operation fusion Macro-operation fusion Micro- ... fusing. Am I correct? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

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assembly - What is non-aligned access? (ARM/Keil)

I'm using Keil to write Assembly for ARM 7. I have the following runtime error: Non-aligned Access: ARM ... , but it fails here first. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Difference between byte ptr and word ptr

I saw the following question on a test paper, Question VarM DWORD ABBF01598h Give the contents of registers al, ... these. Thanks in advance. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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754 views

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assembly - What is instruction fusion in contemporary x86 processors?

What I understand is, there are two types of instruction fusions: Micro-operation fusion Macro-operation fusion Micro- ... fusing. Am I correct? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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898 views

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assembly - SIMD instructions for floating point equality comparison (with NaN == NaN)

Which instructions would be used for comparing two 128 bit vectors consisting of 4 * 32-bit floating point values? ... .se for the long story. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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839 views

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assembly - Find an instruction in an executable file, given its address in a running process?

I'm modifying an old abandonware game to have infinite lives. The Address that has the instruction dec ecx is ... permanently modify the .exe? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

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assembly - Is Little-Endianness a byte order or a bit order in the x86 architecture?

The title says it all. I want to know whether an x86 instruction that reads data from memory, translates its ... as Arabic numbers are written. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Is a memory barrier an instruction that the CPU executes, or is it just a marker?

I am trying to understand what is a memory barrier exactly. Based on what I know so far, a memory barrier ... instructions (for example: mov). See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Move 32bit register into a 8 bit register

Im trying to move edx into al but i get this error lib/io/print.asm:50: error: invalid combination of opcode ... mov al, edx thanks in advance See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Why does returning from _start segfault?

I tried to put code not in the main function, but directly into _start: segment .text global _start ... exit system call exits gracefully. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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896 views

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assembly - Detect/receive multiple key-presses at the same time in DOS?

I'm in the middle of writing air hockey in tasm and I have encounter a problem which is how I get two keys/ ... t really know how to do this. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Segfault when loading from [esp] in 64-bit code

I'm quite new to x86 assembly, and I'm trying to build off a hello world program. I'm trying to make ... ret Why is the program segfaulting? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - llvm-gcc assembler: LDR syntax

This code compiles just fine on gcc, but when using llvm (llvm-gcc), it says "constant expression ... , 0x00000000, 0x00000000, 0x00000000 See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Assembler can't locate existing files

My TASM is mounted to the folder where my my TASM, TLINK, and files are. Specifically it is at C:/TASM ... file: printMzPos1.kt What went wrong? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - How to remove all punctuation and spaces in a string?

I have input like this: This is, ,,, *&% a ::; demo + String. +Need to**@!/// format:::: ... source call WriteString exit main endp end main See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Printing a string without OS

I have a simple program in x86 assembly language. It should print a string directly to the video memory without OS. ... work. Can you help me? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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830 views

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assembly - Is a mov to a segmentation register slower than a mov to a general purpose register?

Specifically is: mov %eax, %ds Slower than mov %eax, %ebx Or are they the same speed. I've ... , where segmentation works differently. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

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assembly - Are there unsigned equivalents of the x87 FILD and SSE CVTSI2SD instructions?

I want to implement the equivalent of C's uint-to-double cast in the GHC Haskell compiler. We already ... conversion (thus losing range)? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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assembly - Segmentation fault when pushing on stack (NASM)

I'm trying to get a nasm program running. The following code: segment .data contAir: dt 1.11330e-10 ... an "illegal instruction" error. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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