Questions tagged [bitwise]
Bitwise refers to a bitwise operation which operates on one or more bit patterns or binary numerals at the level of their individual bits.
278
questions
8
votes
3answers
163 views
“Fast strlen” in C using scalar bithacks
I've translated an implementation of strlen in x86 assembly to C and added alignment checking:
...
4
votes
1answer
117 views
Decoding of binary data (AIS) from socket
I am currently working on a AIS message decoder written in pure Python. It's just a little project to teach me some things about binary data, decoding, etc. Because I am only programming for about a ...
3
votes
2answers
90 views
Byte extension methods for common bitwise operations
I'd like to learn how I can optimize the following byte extension methods.
I'm targeting .NET Standard 2.0 but I'm curious if there are any ways to go about some of this functionality using features ...
2
votes
1answer
78 views
overload c++ enum class operators and enable check value set
I use c++ 11 enum class usually instead of the old enums because many enums can contain the same value
but as known they don't have the bitwise operators out of the box so we should define them ...
2
votes
1answer
23 views
Invert bits of a number in clojurescript
Doing a challenge to print the number that you would get if you convert a given number to binary, invert its bits, then convert back to decimal.
I decided to give it a run in clojurescript (which I ...
4
votes
1answer
61 views
Invert bits of binary representation of number
This is the code I came up with.
I added comments to make the solution more verbose.
...
1
vote
1answer
35 views
LeetCode Count number of set bits solution
Question - Write a function that takes an unsigned integer and return the number of '1' bits it has (also known as the Hamming weight).
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10
votes
2answers
1k views
Bouncing map back into its bounds, after user dragged it out
Users like exploring maps, seeing all that is around. However they tend to go too far. To prevent the map from getting lost to the user it bounces back into the set bounds, as defined by a rectangle.
...
6
votes
2answers
79 views
Count all X-shaped bits from 8 integers
I am given 8 positive 32-bit integer numbers. The task is to write program to count all X-bits.
X-bits are groups of 9 bits (3 rows x 3 columns) forming the letter "X". task is to count all X-bits ...
3
votes
1answer
66 views
5
votes
1answer
130 views
pythonic way to split bytes
I have incoming data from an absolute rotary encoder. It is 24 bits wide. 12 bits are the number of turns and 12 bits are the angle.
I'm reading the data with an Arduino and sending it to the ...
4
votes
1answer
72 views
Binary Trie in F#
I have this little exercise writing a binary trie in F#. In C# it can be done in few lines, but here it became more complicated than I had expected (especially the ...
2
votes
1answer
31 views
Indeterminate-length big-endian to little-endian conversion in Python
I have a need to convert wire encoding (big-endian) to little-endian in Python.
The conversion needs to happen as a separate function; I am not allowed to change the function that reads the byte ...
5
votes
2answers
123 views
Templated division by a power of 2
I've implemented a div_by_power_of_2() function, which lets me force the compiler to use left-shifting rather than proper division, in cases when the developer know ...
7
votes
0answers
52 views
Fun crypto problem: Exploiting a vulnerable encryption scheme with Python
I came across a question asked here and here on the Crypto Stack Exchange site, and decided to analyze it as a kind of case study. To demonstrate the concept, I wrote a short python script depicting ...
1
vote
2answers
99 views
Find out whether number is of Power of Two
The task
is taken from leetcode
Given an integer, write a function to determine if it is a power of
two.
Example 1:
Input: 1
Output: true
Explanation: 20 = 1
Example 2:
...
7
votes
2answers
172 views
Register “%b” conversion specifier
I'm writing a library to register the b, B conversion specifiers and make them work the closest possible to ...
1
vote
1answer
76 views
Go command-line tool to do some simple byte manipulation
I have some files containing 16-bit words in big-endian order, and a tool to process them that assumes little-endian order. I therefore need to swap the order of each pair of bytes in my files.
This ...
3
votes
0answers
96 views
Java code to convert BigDecimal to/from .NET decimal
Background
In many languages we have built-in data types for representing decimal floating point numbers. In .NET that's decimal, and in Java we have ...
4
votes
0answers
124 views
RGB to YCbCr conversion in Java
I found a Go language code to do RGB to YCbCr conversion from here! I ported it to Java:
...
3
votes
1answer
103 views
Division without using division, multiplication, or modulus operators
The task
Implement division of two positive integers without using the
division, multiplication, or modulus operators. Return the quotient as
an integer, ignoring the remainder.
My solution
<...
4
votes
1answer
230 views
Python binary calculator
My task was to build a calculator in Python supporting binary addition etc.
To begin I define a couple of custom exceptions :
...
3
votes
1answer
1k views
Hamming Distance in Python
I was solving this Leetcode challenge about Hamming Distance. Would love feedback on my syntax and code style. Here's the challenge description:
The Hamming distance between two integers is the ...
6
votes
3answers
251 views
Encoding 0/1 bits to 0/255 bytes in C++
I need to map a sequence of bits that represents a float into a sequence of bytes by this rule: the value 1 maps to the value 255 and the value 0 maps to the value 0.
This is the code I have now:
<...
3
votes
5answers
996 views
Largest binary gap
I took a task from Codility to find longest sequence of zeros in binary representation of an integer.
For example, number 9 has binary representation 1001 and contains a binary gap of length 2. ...
3
votes
2answers
322 views
Change Arithmetic Right Shift to Logical Right Shift
The following code is a solution to a textbook (Bryant&O'Hallaron: Computer Systems A programmer's Perspective 2nd Ed) problem in bit-level data manipulation (attempted for the challenge, not a ...
0
votes
1answer
42 views
Implementing carryless multiplication using normal multiplication
In carryless multiplication the partial products are XORed (ie addition without carry) together rather than added normally. The partial products themselves are still the product of a power of two (...
-1
votes
2answers
66 views
0
votes
1answer
28 views
4
votes
2answers
149 views
C bit mask calculator written using GTK+ 3
I've been studying C on my own using K&R 2nd Edition, and started exploring GTK+ to practice some of the concepts I've learned by making GUI applications. This is the first GUI application I've ...
6
votes
4answers
214 views
Efficiently swapping the first and last five bits in an unsigned 16-bit integer in C
I'm programming on an 8-bit Z80 embedded system, and encountered a problem. The program needs to render some pixels to the screen. The color is stored as RGB565 format as a 16-bit unsigned integer, ...
2
votes
1answer
86 views
C++ class for a flag register in a Chip8 emulator
In order to learn C++ I decided to code a Chip8 emulator following a tutorial. When I came across the idea of a flag register and decided it would be fun to implement in order to get familiar with ...
1
vote
1answer
65 views
Maximise XOR of two elements
I have a number x and I need to choose another number y from the given range [l, r] such ...
0
votes
1answer
54 views
Kademlia bucketing
Kademlia is a DHT (distributed hash table) which uses a specific type of routing table, dependent on the Hamming distance between the "addresses" of two peers on the network. I'm attempting to ...
5
votes
2answers
148 views
Circular-shift with variable bitlength
For some memory masking operations I need a bitwise-rotation functionality for unsigned integral types. I came across solutions based on the wiki article, but have not found a variation for a function ...
3
votes
1answer
101 views
K&R Exercise 2-6 : Inserting part of a bitset into another
"Inserting" part of a bitset into another
This is Exercise 2-6 on the K&R book, 2nd edition. The reader is asked to:
Write a function setbits(x,p,n,y) that returns x with the n bits that begin ...
1
vote
1answer
209 views
Adder method of a binary calculator
This is the adder method of my binary calculator. I did not cover for the case that someone passes a non binary number into the calculator yet.
I am pretty sure I have covered every other edge case ...
5
votes
3answers
202 views
Basic binary number container
Summary: a templated class, whose main purpose is to store a binary representation of a decimal number. I choose array of booleans as a storage, since bitset was forbidden. One of the requirements was ...
3
votes
4answers
161 views
Find the longest length of sequence of 1-bits achievable by flipping a single bit from 0 to 1 in a number
Problem Statement
The problem is defined in the book as following:
5.3 You have an integer and you can flip exactly one bit from 0 to ...
4
votes
2answers
112 views
Checking if a number is a power of 2 without loops
I made a short program which checks if a number is a power of 2 without using any loops.
The idea: A number which is a power of 2 must have only one bit "1" ( ex: 8= 1000, 4=100 and so on).
Suppose ...
2
votes
0answers
77 views
Kaitai Struct: shift rotate >1 byte groups
This is an implementation of rotation (cyclic shift) of many-byte groups to the left. Rotate right is supported as negative amount. I would like to request, if someone would be willing, to review this ...
4
votes
1answer
72 views
Check digital input signals that is sent as an integer using bitwise checking
I have a program that works with a hardware via an ActiveX API. The API have events that is triggered by the hardware.
In the hardware there is an IO card. There is 16 in and 16 out. Changes in input ...
6
votes
2answers
800 views
Bitwise comparison of any structure
What I tried to do is compare arbitrary structures independent of the == operator implementation.
...
5
votes
1answer
110 views
C++ container — variable byte coded numbers list
I'm writing a container for unsigned integers, which uses variable byte coding. It works but some decisions I took look ugly so I would be glad if you gave me some hints for improving the design.
I ...
7
votes
4answers
606 views
Calculating linux based octal file permission
I'm applying for a mid level devloper position.
In order to progress to 2nd interview, you need to pass a technical test.
One of the questions was to write a function to work out linux based octal ...
2
votes
1answer
205 views
Reading/writing single bits from/to FILE
I'm implementing a Huffman encoding/decoding program and I need a way to deal with single bits.
I tried to keep things as simple as possible, I "pack" bits inside a single byte and I have only one ...
1
vote
2answers
2k views
6
votes
1answer
527 views
Bitfield class and Register depiction
For a few months now I have been working with an ARM CPU. To be specific an ARM Cortex M3 from STM (STM32107VC). Complete example
So far I am using the StdPeriphal library, and will continue to do so ...
3
votes
1answer
54 views
An application that compares two lists of byte strings
I am a beginner in Rust, and I am trying to write a program that compares common bits between two lists of bits. The program below does that (with the variable names indicating the domain of ...
5
votes
2answers
145 views
Map a range of integers to a 64-bit integer
Given a 64-bit integer x (which is always larger than 0), we wish to map it to an index so that:
when x is between 0..64, we map it to 0,
when x is between 65..128,...
