Questions tagged [machine-code]

Machine code is the lowest level form of encoding instructions (binary). It is usually what the processor directly decodes and executes.

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Why did Intel chose 90h machine code for their NOP instruction instead of a 0?

Probably just a historical question, if anyone knows.
c00000fd's user avatar
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1 vote
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what is Max operating temperature of TASSIMO Bosch My Way [closed]

Having read the articles regarding changes to barcodes on Tassimo Coffee Machines, I was wanting to know if the water temperature could be changed to a hotter setting if possible via the barcodes. ...
Ivor Mac's user avatar
3 votes
1 answer
92 views

Reverse engineer a blackbox function operating on single or double precision floats for emulation

I own and run a NEC VectorEngine 10C which is a PCIe accelerator running a proprietary ISA which has many fun instructions among them is VRSQRT which computes an approximation of the inverse ...
worldsmithhelper's user avatar
0 votes
3 answers
2k views

How to extract machine code from a file(especially executable) in C

How to get machine code of a file(mainly executables) in C? I have written a C program to convert machine code to assembly. But how to get machine code of a file? How would I go about programming a c ...
BleepLogger's user avatar
2 votes
1 answer
165 views

How do you build a virtual machine to interpret machine code?

How does the parser parse the machine code? Does it go byte by byte? How does it know how many bytes to read when parsing an instruction? Does it have some sorts of tables of bytes to translate the ...
Lance's user avatar
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2 votes
2 answers
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How to test and debug x86 Assembly exceptions in NASM?

I have seen all the exception "IDs" in the Intel Manuals, and just came across sandpile's exception guide, which actually shows some hexcodes. For example, "divide by zero error": ...
Lance's user avatar
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0 votes
1 answer
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How to increment and decrement machine code in radare2?

I watched a video (I believe it was a talk by the author of radare2) of how to increment machine code in radare2 very easily, simply by hitting 'c' and then using + and - to respectively increment and ...
AlphaCentauri's user avatar
3 votes
2 answers
4k views

Can Machine Learning be used to develop better reverse engineering tools? [duplicate]

So i googled this but other than some papers i couldnt find any reverse engineering tool that was built using machine learning I'm not an expert in machine learning and deep learning but it seems ...
John P's user avatar
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2 votes
2 answers
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How identify witch cpu run assembly [duplicate]

I have around 300 bytes of binary machine code. I don't know which instruction set the code is for so I can't open it with IDA. Is there any tool that can help identify the instruction set?
FIF9K9J's user avatar
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1 vote
2 answers
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how data types and variables are converted to machine code?

I know that every x86 instruction has an opcode for that, but I don't know how data types and variables are converted to machine code. So I tried to figure out. I wrote a simple C program and ...
Naveen prakash's user avatar
3 votes
3 answers
2k views

Building a control flow graph from machine code

I want to write my own soft, that can disassemble code, and turn it into conrol flow graph. Now i know the basics of graph theory, but i don't get where i should start, do i need to basically keep the ...
WokNoodlesWithOysterSauce's user avatar
3 votes
3 answers
6k views

Determind length of instructions in bytes

Where is it possible to find a list of x86 instructions (and x64 instructions) with the (hex) opcode and the length/size in bytes of the instructions, such as: 0x90 = NOP = 1 byte 0xE9 = JMP = 5 ...
vallentin's user avatar
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1 answer
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Which architecture is this machine code?

I dumped a ROM recently. I tried to disassembled the machine code* for many architectures, but I always got assembly which, at best, looked like garbage. Note: I can perfectly read the strings the ...
rvkolp's user avatar
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3 votes
2 answers
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How to identify code ran when clicking on an object in a game

I've played with using software like cheat engine to modify memory, null out code and even inject some code of my own. However finding the right spot to modify is always a difficulty. I'd like to be ...
FraserOfSmeg's user avatar
4 votes
2 answers
1k views

Difficulty of reverse engineering based on target

I'm not asking about the difficulty of reverse engineering in general, but rather the difficulty of reverse engineering a particular hypothetical target. We'll assume that having the source code ...
E Lee's user avatar
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3 votes
2 answers
339 views

One-pass streaming algorithm for detecting bytecode/opcode?

I am searching for an algorithm and/or snippet of code that provides a one-pass algorithm over a steady datastream that can detect a valid sequence of bytecode or opcode. There are no PE32, ELF, or ...
John Greene's user avatar
1 vote
1 answer
1k views

Code-Cave Assembly Patching Issue in x64_dbg

I'm trying a code-cave approach to this query that was asked about on this forum earlier. I'm using x64_dbg to perform this task. My issue here is that after I have written the extra lines of ...
Pramod Mohandas's user avatar
2 votes
0 answers
229 views

Decoding A/C IR Codes

I captured infrared codes from an air conditioner remote to realize each code contains the entire state (i.e. temperature, mode, fan speed, etc.) every time a button is pressed. I believe this is so ...
dranger003's user avatar
2 votes
2 answers
339 views

Reverse engineering and programming byte-by-byte on mobile OSs?

I can't find any disassembling programs for the various binary formats out there that can run on OSes like Android, iOS, Blackberry, etc. These are the only devices I have access to, and I am trying ...
TomHardyBoyyy's user avatar
5 votes
2 answers
3k views

how can the processor instruction set be identified solely by examining a binary image? [duplicate]

Constraints: I am doing reverse engineering of a binary firmware image of unknown provenance, which operates on a device that is not physically accessible to me. That is, I can't take apart the ...
Edward's user avatar
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-1 votes
3 answers
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Any programs that can convert textual ones and zeroes to full comparison bytes?

since the byte is the lowest addressable datum and bit rotating/flipping can come in to play here, are there any programs that can enable you to write ones and zeroes (binary), and after every 8 of ...
OllyDebugger's user avatar
1 vote
0 answers
107 views

How to write bit-by-bit to a medium, as opposed to byte-by-byte? [closed]

I am trying to write binary opcodes, but I can't in a text editor as 1s and 0s because: 1 or 0 on a text editor ends up being stored as the literal ASCII equivalent code on the storage medium, not ...
Tracker Boots's user avatar
6 votes
1 answer
1k views

I need quick correction on this x86 opcode conundrum

I am trying to figure out how to encode the instruction MOV DS, AX, but I am confused from the opcode table as follows: Is MOV DS all one byte, or is MOV one byte, DS the second, and the AX the third?...
Jonas' River's user avatar
2 votes
2 answers
357 views

Issues writing a bootloader in x86 16-bit machine code

I am having trouble displaying simple text. I am trying to do it all in machine code with INT 10h, but: I can't find the binary opcode for INT 10h anywhere in the Intel Manual. I can't figure out how ...
Tomahawker's user avatar
-2 votes
1 answer
208 views

Is there always 1:1 correlation between hexadecimal and binary?

I was wondering this because I have found that some instructions, on the machine code level, are too large if taken a step down from hex to 0s and 1s. On Motorola 68000 I found that some instructions ...
Lucky Wicker's user avatar
-5 votes
2 answers
1k views

Can anyone here show me the binary opcodes for these x86 assembly instructions? [closed]

I want the exact binary opcodes executable to CPU directly. [BITS 16] ; 16 bit code generation [ORG 0x7C00] ; Origin location ; Main program main: ; Label for the start of the main ...
assembling girl's user avatar
8 votes
1 answer
295 views

How to view the instruction pipeline?

Instruction pipelining is used to execute instructions in a parallel fashion by dividing them into several steps .When I pause the execution in a debugger I am only able to see the location of the eip ...
viv's user avatar
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10 votes
1 answer
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Common Lisp bytecode or machine code decompiler

Does anyone know of a decompiler for Common Lisp? I know most lisp environments include a disassembler. But I don't know of any decompilers. I would think it should be possible to make a decompiler ...
cb88's user avatar
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