Questions tagged [machine-code]
According to Wikipedia, Machine code or machine language is a set of instructions executed directly by a computer's central processing unit (CPU). Each instruction performs a very specific task, such as a load, a jump, or an ALU operation on a unit of data in a CPU register or memory. Every program directly executed by a CPU is made up of a series of such instructions.
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Are shorter variants of machine instructions worth it?
I'm writing a JIT runtime, and I've started thinking about shorter variants of some instructions.
In x64 we can do at least two kinds of jumps: rel8 and rel32. The first one takes say 2 bytes (opcode +...
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why do we need instructions set for processor or controller?
Why is it necessary to have an instruction set for processors and controllers? Can't we simply convert high-level language programs, like those written in C, directly into binaries without the need ...
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How do binary numbers interact with the CPU and cause some action to take place? [duplicate]
EDIT: Perhaps what I am misunderstanding is that when it is said that the code we type gets turned into machine code of 0s and 1s. If these 0s and 1s are the abstracted representation of their ...
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is the relocatable machine code essentially the text segment of the virtual address?
Sorry if this is a basic question, I'm studying for my operating systems class and compiler theory class at the same time and this is confusing me. From what I do understand, virtual memory is larger ...
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How to Write Pure Machine Code for Linux?
I'm writing a compiler, and I want it to compile to a native executable (just Linux, for now). I don't want it to be Assembly, it needs to be PURE machine code. Can anyone point me in the right ...
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Meaning of Machine in Compiler Theory
Can anyone tell me what does "machine" means in Compiler Theory? Does it mean computer in general or operating system? Actually, the problem is I understand the definition of machine language as "the ...
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Why do we use the symbols 0 and 1 for two-state logic?
We know a regular computer basically only knows two states and that we name these states 0 and 1 respectively. This seems arbitrary, we could name them "a" and "b", or even 3 and 4. Is there a reason ...
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Intel Memory Addressing Form
I'm am trying to understand machine code memory addressing for x86, and I've encountered two opposing general forms for addressing (using the ModRM and SIB bytes).
Most unofficial resources I consult ...
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What is 16 bit word's equivalent in decimal?
Question:
For a 16 bit word with 6 bits for an opcode
How many different instructions could I fit into the instruction set?
What is the largest number that I could use as data?
Answer:
...
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"Write an Assembler in C." Why writing a machine code translator for a low level language in a higher level language?
My Microprocessor class instructor gave us an assignment and said:
"Write an Assembler in C." - My beloved Professor
So it seemed a little bit illogical to me.
If I'm not wrong Assembly ...
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Operation excution in terms of clock cycles
Typically for a single instrcution, 6 machine cycles are needed:
FETCH instruction
DECODE instruction
EVALUATE ADDRESS
fetch OPERANDS
EXECUTE oepration
STORE result
My concern is regarding the fifth ...
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What is involved in compiling or interpreting machine G-Code?
The G-Code and M-Code that we used to instruct CNC lathe, 3d-Printers and engraving machines, to my understanding, is not a programming language, but a scripting language like Python where scripts ...
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Compilation to bytecode vs machine code
Does compilation that produces an interim bytecode (like with Java), rather than going "all the way" to machine code, generally involve less complexity (and thus likely take less time)?
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Computer Language vs. Protocol Comparison
How to explain the difference between a programming language and a protocol?
Can a protocol have extensions?
We know that machines communicate with a protocol, but they can also communicate with ...
zukerman yoav
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Machine code JITs and the Execution Disable bit
How is runtime-generated machine-code (such as the output of a JIT), actually executed by the CPU if the CPU/OS has an Execution Disable bit?
As far as I know, many modern processors and Operating ...
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Why do executables depend on the OS but not on the CPU?
If I write a C program and compile it to an .exe file, the .exe file contains raw machine instructions to the CPU. (I think).
If so, how is it possible for me to run the compiled file on any computer ...
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How does an optimizing compiler react to a program with nested loops?
Say you have a bunch of nested loops.
public void testMethod() {
for(int i = 0; i<1203; i++){
//some computation
for(int k=2; k<123; k++){
//...
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Is it possible to implement a native compiler for a 'managed language' such as Java?
In most cases, it is possible to create both a native compiler and an interpreter for a programming language. The compiler would simply convert the source code to machine code, and the interpreter ...
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Is machine language always binary? [duplicate]
I know absolutely nothing in low-level stuff, so this will be a very newbie question. Please excuse my ignorance.
Is machine language - the series of numbers to that tell the physical computer ...
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Do compiler-writers actually need to 'understand' machine code? [closed]
Might be kind of an odd question.
A guy writing a C++ compiler (or whatever non-VM language): Does he need to be able to read/write raw machine language? How does that work?
EDIT: I am specifically ...
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Creating a very basic compiler using Java
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 idea ...
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Why can't native machine code be easily decompiled?
With bytecode-based virtual machine languages like Java, VB.NET, C#, ActionScript 3.0, etc., you hear sometimes about how easy it is to just go download some decompiler off the Internet, run the ...
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How does assembly relate to machine/binary code
How does assembly relate to machine/binary code.
For example here is how to print to the screen in mikeOS(a small pure assembly OS), mikeOS it uses NASM to assemble.
BITS 16
ORG 32768
%...
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Fetching instructions from memory
So, I am a noob in assembly language and machine instructions.
When the discussion came up as to how funtion calls are implemented at the processor level, someone said that the CALL instruction ...
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What did machine code for 4-bit architecture look like?
I don't know how a 4-bit instruction could be enough to do something so I read about the Intel 4004 and it says that it used 8-bit instructions and then I can understand how opcode and numbers has ...
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Is it possible to use GNU GPL for application that has no source?
I mean, it is possible to create application without source code - for example using HEX editor or some debugger that can assembly instructions (actually every decent debugger can).
Creating programs ...
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Do compilers have to be written for each model of CPU?
Do you need to take account of the different processors and their instructions when writing a compiler? Have instructions been standardised? Or what tools and techniques are available to assist with ...
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How is software for machines such as ATMs or TVs built?
As a beginner programmer I've only worked with programming computer based applications, but a question has been coming to my head very often since I started programming and I can't get it answered ...
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Resources on learning to program in machine code? [closed]
I'm a student, fresh into programming and loving it, from Java to C++ and down to C. I moved backwards to the barebones and thought to go further down to Assembly.
But, to my surprise, a lot of ...
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Is there any example or resource explaining/showing code from High-level to Low-level to deep down Machine code? [closed]
I have been searching for an example over the internet that shows any operation like saving a file or drawing anything in UI or any other sort that shows the implementation from High-leve language ...
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