machine-code Questions

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I'm currently working on a compiler project using llvm. I have followed various tutorials to the point where I have a parser to create a syntax tree and then the tree is converted into an llvm Modu...
Comportment asked 19/11, 2012 at 23:27

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What does rep; nop mean? Is it the same as pause instruction? Is it the same as rep nop (without the semi-colon)? What's the difference to the simple nop instruction? Does it behave differently on...
Gristle asked 16/8, 2011 at 23:12

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I am new to programming and I started with C++ language, as far as I know C++ language is converted to assembly language by the C++ compiler (Ex:Visual Studio), but I tried looking up for what conv...
Singsong asked 25/7, 2014 at 4:35

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I am coding a ftrace program on Linux(64 bits) for study purpose, and I need to parse the instruction using ptrace() syscall. The instruction I am interested in are ret and call. The call instruct...
Ivette asked 30/6, 2015 at 9:12

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Hi, x86 assembler geeks! I have an interesting problem to test your assembler programming skills. I'm the author of this problem, so I know the correct answer. Your task is to implement log...
Trio asked 10/6, 2015 at 15:53

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I'm trying to learn to use the cortex m0 processor. I have a stm32f0 development board which lets me view each bit of each address and upload a new binary file easily. I've been reading a lit of ma...
Teleprinter asked 27/4, 2015 at 5:3

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I'm writing a JIT compiler in C for x86_64 linux. Currently the idea is to generate some bytecode in a buffer of executable memory (e.g. obtained with an mmap call) and jump to it with a fun...
Storage asked 22/4, 2015 at 12:39

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I am writing an assembly program on the LC3 machine. My assembly program is an LC3 program that multiplies R2 and R3 and stores the result in R1. Here is my source code(with comments) ;Sets pc ...
Piffle asked 17/4, 2015 at 20:12

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This question is begging for a bunch of "why are you doing this?" responses. I haven't been able to find this information in the 68k Programmer's Reference Manual, but that may be because I'm not ...
Cottonmouth asked 9/6, 2011 at 21:11

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In looking at an x86 opcode map such as this: http://www.mlsite.net/8086/#tbl_map1 It defines mappings, for example: 00: ADD Eb,Gb 01: ADD Ev,Gv ... That link has basic descriptions of what th...
Aaren asked 22/2, 2015 at 23:46

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I'd like to know how is it possible to write something as simple as an Hello World program just by using an Hex Editor. I know that I could use an assembler and assembly language to this at a near ...
Gemmagemmate asked 31/7, 2012 at 15:30

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As I use objdump -D to disassemble a binary, the typical code of jmpq is like e9 7f fe ff ff, which is used for representing a negative offset. However, the address of x86-64 is 64(48)-bit (to my k...

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I'm looking for the most portable assembler library, like asmjit or jitasm. When I say 'most portable' I mean, that has the most support for a wide verity of architectures. Language doesn't matter...

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I'm using emu8086. I've a question which tasked me to display what we see on seven segment displays after converting from its hexa inputs. I should input my data in hexa, if it matches the hexa inp...
Sherbet asked 1/10, 2014 at 16:6

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I know how to get the opcodes and the corresponding assembly syntax from an executable; however is there an easy way to get the opcodes of a particular assembly instruction alone, without writing a...
Pair asked 23/1, 2011 at 16:10

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After reading some answers from the site and viewing some sources, I thought that the compiler converts high-level language (C++ as an example) to machine code directly as the computer itself doesn...
Ulterior asked 25/7, 2014 at 21:33

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I was wondering, is it possible to get eyes on the actual machine code that the HotSpot compiler generates when it compiles a given Java bytecode class or method?
Gasket asked 12/7, 2014 at 23:44

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This question is a follow-up to that question. To set the context of this question, consider Null-free programming. This is a technique to masquerade a sequence of instructions (shellcode) as a st...
Masterpiece asked 5/7, 2014 at 12:5

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I'm about to start optimizations on an enormous piece of code and I need to know exactly which operations are performed when the modulus operator is used. I have been searching for quite a while, b...
Haema asked 2/4, 2013 at 0:47

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One site that I commonly refer to for x86 documentation has a few instruction codes with a slash and a number. For instance, jmp near absolute indirect gives FF /4, whereas jmp far absolute indirec...
Kaslik asked 18/6, 2014 at 21:42

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I want to try and create my own very basic language, with it's very basic compiler. All using Java. For now, it will only need to enable to 'programmer' to print things to the screen. I had an id...
Benz asked 3/3, 2014 at 9:19

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I am new to Assembly language. I was reading about the MIPS architecture and I am stuck with the Jump Target Address and Branch Target Address instructions and how to calculate each of them.
Yelp asked 5/8, 2011 at 0:40

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Using amd64 assembly, whats the best way to zero out the top 32 bits of a 64-bit register, e.g. zero out the bits of rax that are not covered by eax? It appears that I cannot and the whole register...
Hairpin asked 29/1, 2014 at 18:16

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For example, when I compile a C application is the outputted file read as binary or does the OS then interpret the compilation? Is the "machine language" pure binary? EDIT: Yes, everything on a co...
Italian asked 27/7, 2011 at 1:16

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I have created a programming language, from scratch with C. I have built a compiler which processes the code in the input file and converts it to tokens and checks that the tokens are in the correc...
Unpolite asked 29/12, 2013 at 19:1

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