# 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.

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### Set a specific bit to a specific value

This is the code I came up with: ...
95 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 ...
41 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 ...
340 views

### Rotating 3D bit board in C

I've got a 64 bit bitboard, but instead of interpreting as an 8 by 8 binary matrix, as is usually the case, I've taken it to the third dimension, so to speak. Now mirroring and even rotating by 180 ...
71 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 ...
29 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 ...
119 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 ...
39 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 ...
87 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: ...
135 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 ...
463 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 ...
56 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 ...
71 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: ...
85 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 <...
14k views

### Find the binary gap of a number N

For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 529 has binary representation 1000010001 and contains two binary gaps: one of length 4 and one of ...
9k views

### 16 bit checksum calculation [closed]

I need to calculate checksum using 16-bit ones' complement addition: ...
106 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 : ...
493 views

### Codility “PermMissingElem” Solution

This is my solution to the PermMissingElem problem, I wonder what can be improved? Expected worst case time complexity is O(N), but the performance test shows that it's O(N) or O(N * log(N)), which I ...
64k views

### Pack and unpack bytes to strings

I need to write a function that "packs" an array of bytes (integers between 0 and 255) into a string. I also need to be able to perform the reverse operation, to get my byte array from the string that ...
450 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 ...
11k views

### Counting the number of bits of a positive integer

How can I improve this code for counting the number of bits of a positive integer n in Python? ...
244 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: <...
7k views

### Printing longest sequence of zeroes

I am doing a coding exercise in codility and I came across this question: A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ...
496 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. ...
120 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 ...
497 views

### Creating and storing binary arrays

I recently created a library in C, which creates and stores binary arrays. My library uses the standard fixed data types and allocates no more than 8 bytes for a binary array (8 bytes = 64-bit ...
32 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 (...
127 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 ...
28 views

### Given an integer, return its binary representation. You cannot use any Integer.toXXXString methods

Here is my code: ...
65 views

### Given an integer number, invert its bits. You cannot use the ~ operator

Here is my code: ...
199 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, ...
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### 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 ...
63 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 ...
125 views

### Routine for convert decimal digits to Densely Packed Decimal

I've written an amd64 assembly routine (in gas syntax using the System V calling convention) to convert three decimal digits to Densely packed decimal because I wasn't satisfied by the performance of ...
51 views

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 ...
120 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 ...
8k views

### Calculating the 'binary gap' of a number

Inspired by this question and therefore this one I decided that clearly the best most readable way to solve this is with Regular Expressions. A binary gap within a positive integer N is any maximal ...
3k views

### “Flipping bits” Python implementation

Problem Statement You will be given a list of 32 bits unsigned integers. You are required to output the list of the unsigned integers you get by flipping bits in its binary representation (i.e. ...
2k views

### Codility binary gap solution

This is how I solved the binary gap problem: Find longest sequence of zeros, bounded by ones, in binary representation of an integer I wonder how does it fare against solutions such as ones appeared ...
171 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 ...
91 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 ...
180 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 ...
144 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 ...
111 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 ...
53 views

### Bit stream input in Factor

My attempt at writing code to input values of arbitrary bitlength based on a bytearray in Factor. Any comments on the correctness or style would be appreciated. ...
986 views

### Template for endianness-free code, data always packed as BIG-Endian

It's been a while since I've been properly grilled about my code. I had this Idea which should probably never make it into production code but still I couldn't find anything seriously wrong with it ...
73 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 ...
67 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 ...