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Questions tagged [assembly]

An assembly language is a low-level programming language for a computer, or other programmable device, in which there is a very strong (generally one-to-one) correspondence between the language and the architecture's machine code instructions.

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38 views

Quick sort in assembly x86 language [closed]

here is the link to the file below mboshart.dyndns.org/~mboshart/3410programs.html#prog3 Allow the user to enter a number of strings up to a maximum of 100 (MAX EQU 100). Set the maximum length of ...
18
votes
1answer
185 views

Brainfreeze: A Brainfuck compiler in C

BrainFreeze This is my implementation of a brainfuck compiler in C. The instruction to build/run the project (GitHub repo) can be found here. I am first converting the brainfuck source to x86 ...
11
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3answers
2k views

Decoding assembly instructions in a Game Boy disassembler

I am coding a game boy disassembler in C++. The program (simplified here) converts a vector of byte into an assembly instruction and print it. To do so, it iterates through the vector of bytes (char)...
1
vote
1answer
38 views

Multi-line text reader (x64 ASM)

Building upon my previous question, I have come up with a method that'll search through a buffer and return a pointer to the end of the line. The primary purpose of the function to extract rows from a ...
3
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1answer
77 views

Reading all file contents via x64 assembly

I have come up with the following snippet by building upon the answers given to my StackOverflow question. Just trying to get some other eyeballs to review things so that they can point out any ...
13
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1answer
109 views

Brainfuck to NASM compiler in Haskell

After reading this article on writing a Brainfuck interpreter in Haskell and achieving awful performance with it (for example, mandelbrot generating 37.5 minutes on an old Intel Atom powered laptop) I'...
3
votes
3answers
106 views

A simple shellcode that will kill all your processes GNU/Linux x86_64

So I made a simple shellcode that will kill all your process. Now I would like to know, can it be done in some better way? It contains 13 bytes. Thanks for all your feedback Assembly: ...
4
votes
3answers
216 views

strlen and strcmp implementation in x86 FASM assembly

I wrote my own implementation of strlen and strcmp from C in x86 FASM and I would like to know is there anything that should be changed or improved. strlen needs string in eax and is returning length ...
4
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0answers
69 views

Collatz Conjecture Disprover Unit - Googol Edition

The Wikipedia article about the Collatz Conjecture has these quotes: If the conjecture is false, it can only be because there is some starting number which gives rise to a sequence that does not ...
6
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4answers
177 views

Find some X^2 - Y^2 equal to a given Z

Request input (Z) from user, \$-65535 \leq Z \leq 65535\$. Check if \$(X^2)-(Y^2)=Z\$ (while \$0 \leq X,Y \leq 1000\$). I wrote a code which will receive Z from user, if it's negative, store the ...
4
votes
2answers
101 views

Test whether a number is a Harshad Number

A little code I wrote that will check if the entered 4-digit number is Harshad or not (Harshad number is one which divided by the sum of its digits will leave no remainder, special Harshad is the same ...
3
votes
1answer
81 views

Expand every bit into a byte

I have the following code: ...
3
votes
1answer
30 views

X86 Feature detection in preperation for Long Mode

These are the three steps that need to be taken in order to successfully activate Long Mode. Error reporting is sparse as most real hardware for developing an OS is 64 bit but probably still a good ...
4
votes
1answer
27 views

Compare two strings in extended memory - classic 8052

I'm looking for a simpler code that isn't resource hungry that can compare two strings stored in different locations in the extended memory of a classic 8052 (namely the AT89S52 microcontroller) to ...
1
vote
0answers
15 views

Swapping variable length strings asynchronously with connected microcontroller (Byte-banging)

I have an AT89S52 and an AT89C4051 microcontroller (both in the 8052 family) in which the bit lines of the data bus, one control pin and one status pin are connected together. In code, the data bus is ...
3
votes
3answers
486 views

Simple puts() function in x64 assembly

I'm trying to write as simple I/O library in x64 using linux syscalls ...
1
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1answer
49 views

Variadic Functions in NASM Win64 Assembly

Simple variadic function implementation in NASM Assembly. When implemented like I have below: sum.asm ...
6
votes
1answer
255 views

Tower of Hanoi in NASM Win64 Assembly

This program is an implementation of the classic puzzle Tower of Hanoi! This is my first mostly recursive Assembly program. Any advice and all topical comments on code optimization and conventions is ...
2
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0answers
70 views

x64 Windows Assembly - Structs in Assembly

I'm trying to code a simple person database using structs and arrays in assembly. Each person has a firstName, lastName, ...
1
vote
1answer
104 views

Guessing game in NASM Win64 Assembly

Still learning Assembly. This program is a simple guessing game to test most of the new things I've learned! Any advice and all topical comments on code optimization and conventions is appreciated! ...
20
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3answers
3k views

Checking if a number is prime in NASM Win64 Assembly

I'm just learning Assembly. This program is a simple attempt to determine if a given number is prime or not. Any advice and all topical comments on code optimization and conventions is appreciated! ...
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1answer
72 views

gcc constant time implemenation [closed]

I need to make the following function time constant - I have already removed if statements and have written it down to one line in the loop. ...
4
votes
1answer
110 views

Main loop in assembly for a Brainfuck interpreter

I have written 2 Brainfuck interpreters, one in C++, then another in C++ with Assembly inner loop. My interpreter code can be found here (C++/ASM, requires MSVC and MASM) and here (C++). Both are ...
3
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1answer
118 views

Hex Dump Utility in x86-64 Assembly: Version 1.1

I recently posted a code review and received some very useful feedback. I have spent some time implementing the suggested improvements/fixes, and wish to post a follow up review, with the new and ...
6
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2answers
217 views

Hex Dump Utility in x86-64 Assembly, under Linux

As a relative newbie to Assembly programming, although I can get my programs to work, I have no idea if they are disastrously constructed or not. I have created a simple Hex Dump Utility, using x86-...
3
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2answers
100 views

Disassembler for intel 8080 v2

As many suggestions were given for the code I posted here, I decided to show you the new version for review. I Removed the OpenCatalog class, ...
10
votes
2answers
187 views

Disassembler for intel 8080

I have written a disassembler for Intel 8080, able to translate binaries into opcodes and parameters. Sorry for posting so much code, but everything posted here is useful for the understanding of the ...
10
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1answer
1k views

string length in x64 assembly (fasm)

Please critique this very, very basic routine which returns the length of a given char buffer or "string." ...
1
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0answers
448 views

MIPS Assembly Program to access elements in the 4x4 matrix, row or column-major oder

This MIPS Assembly program will make you access the elements in the 4x4 matrix in either row or column-major order i.e. accessing all elements row by row or column by column. Output is posted below ...
5
votes
1answer
75 views

Console TicTacToe implementation

I am new to assembly and I want to know how I can improve this implementation both by speed and/or binary size optimization and making code to read and support easily. Platform: Linux, x64 Assembler:...
5
votes
2answers
79 views

Multiplying big numbers using Long Multiplication

Three weeks ago I posted Multiplying big numbers using Karatsuba's method where I made reference to my version of the classical long multiplication. That's what I'm posting today so people can compare ...
1
vote
1answer
400 views

Linked List in x86 assembly(MASM)

Module 1: ...
5
votes
1answer
73 views

Block Allocation in Fixed-Size Block Allocator

The following routine is the block-allocation procedure in a fixed-size allocator being written for library use. It is designed to be accessed from C++ (the un-mangled symbol name is ...
6
votes
1answer
316 views

SIMD memcpy assembler implementation

I am fairly rusty with assembler, let alone the AT&T syntax. I would appreciate it if someone with more experience could please review the following memcpy implementation. Note that this will only ...
12
votes
0answers
134 views

Multiplying big numbers using Karatsuba's method

The Karatsuba algorithm, first published in 1962, aims to speed up the multiplication of big numbers by reducing the number of 'single-digit-multiplications' involved. Because of its complexity (...
6
votes
1answer
730 views

Convert unsigned Integer to ASCII in x86 assembly

This is my best effort to code an x86 32 bits to get an unsigned int (4 bytes) and convert it into a string. My strategy was successively divide the number by ten and fulfill the remainder of the <...
5
votes
1answer
430 views

Dynamic Fibonacci algorithm in x86 (MASM)

My task was to implement this algorithm that uses memoization to calculate fibonnaci numbers: ...
6
votes
1answer
845 views

Quick Sort in x86 assembly (MASM)

My task was to implement Quick Sort in assembly from pseudocode. ...
25
votes
2answers
2k views

Euler's Totient Function in x86 assembly (MASM)

My task was to implement Euler's totient function, and I'm looking for any and all criticism. ...
9
votes
2answers
148 views

Caesar cipher in i686 assembly + MMX

I have written the following implementation of the Caesar cipher for an old Linux computer with a Pentium MMX chip. The code has been written with the following design goals in mind: the code should ...
10
votes
1answer
171 views

A 8086 assembly hexdump program

I am trying to learn the 8086 assembly language. So as exercise, I decided to write a hexdump program, that outputs the contents of files in a format similar to Linux hexdump. I am developing under ...
11
votes
0answers
145 views

Signed integer-to-ascii x86_64 assembler macro

I have implemented an algorithm which converts a signed integer to its ASCII equivalent string with the corresponding sign as a first byte. I have tested it on several numbers and it worked correctly. ...
6
votes
1answer
153 views

x86 FASM assembly Reverse FizzBuzz

This program counts down from 100 to 1 and: If the current number is a multiple of 3 it prints "Fizz" instead of the number If it is a multiple of 5 it prints "Buzz" instead of the number If it is a ...
2
votes
0answers
2k views

Bubble sort using user inputted numbers and size in MIPS assembly

I made this code to take user input, making a specific-sized array and printing user-inputted numbers after being sorted. It works well but I was wondering if there was a way to "shrink" it down. It ...
13
votes
2answers
155 views

Calculating (\$a^2\$ + \$b(2c-d)^2)/(3e)\$ in assembly

I made a simple assembly program to evaluate the function $$f =\frac{a^2 + b(2c-d)^2}{3e}$$ Since this is basically my first ever, I would like to hear what I can improve and know how to use ...
4
votes
1answer
93 views

x86 assembly [fasm] code which takes a number and adds 155 then shifts right

The following program takes a user-inputted integer and adds 155, shifts it to the right twice, and prints the output after the addition, then after the shift. It is written in fasm x86 assembly and ...
5
votes
1answer
56 views

Print which CPU flags are set at the start of the program

This is my first "real" x86 program developed from scratch. Please critique: ...
10
votes
1answer
601 views

Measuring the clock rate of an Intel CPU in C++

I created a short program to directly measure the clock rate of an Intel CPU. It runs, sleeps for a duration specified by the user, and then measures the number of clock cycles and the amount of time ...
3
votes
0answers
180 views

Implementing binary-heap in x86-64 assembly

I'm trying to implement some of the simplest classical data-structures in x86-64 assembly on linux. PRIMARY GOAL: Reduce memory consumption and increase performance (maybe using x86-64 architecture ...
2
votes
0answers
33 views

Write 16x16 bitmap to frame buffer

The following code writes a 16x16 bitmap to a framebuffer using up to AVX2 instuctions. I'm sure it can be improved with AVX512 ...