# 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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### Copy arbitrary number of bits at arbitrary offset from buffer to another buffer

I have just written a function copy_lowbits_off to copy any number of bits (not bytes) from a source buffer to a destination buffer. The function also supports ...
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### Efficiently counting '1' bits in the first n bits

I have two functions to count the number of set '1' bits in the first offset bits of either a 64 bit number, or a bitmap struct. After some profiling, particularly ...
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### 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 ...
402 views

### Count bits in VBScript

I'm trying to write a function that returns the number of bits set in a 32-bit integer in VBScript, it's just for practising the language. The function I've written so far looks okay, but I'm ...
228 views

### Using bitwise operators with (unsigned long) instead of bitfields

Here is my solution to Programming Exercise 15-7 from Stephen Prata's C Primer Plus, 6th Edition. This problem asks the reader to: 15-7 Write a program with the same behavior as described in ...
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### Solution to part 1 of Day 7 Advent of Code in Scala

Does someone want to review my solution to part 1 of Day 7 Advent of Code in Scala? The assignment is here: http://adventofcode.com/day/7 Without repeating the whole text, in short: Given a text file ...
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### Connect Four: Bitboard checking algorithm

I'm rather new to Clojure and so I decided to program a Connect Four for fun and learning. The code below is a Clojure implementation of this bitboard algorithm. The whole code can be found here: ...
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### 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 ...
1k views

### Parsing GSM 7-Bit messages in Java

I wrote a function to decode GSM 7-Bit encoded messages as defined in the 3GPP standard. Example available here. I found a tool to help me check my answers here. I used the charset from here. ...
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I have implemented the LEB128 encoding for unsigned integers. I'm fairly new to Haskell so I have some doubt about the coding style I'm using, particularly the definition of ...
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### 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. ...
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### Bitwise Flag code for Python

I am looking for feedback on this compact Python API for defining bitwise flags and setting/manipulating them. Under the hood, FlagType extends int and all ...
88 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: ...
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### Bit Vector implementation

Looking for a general review. ...
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### Parallel popcount of packed bytes

I want to do a popcount of bytes in an array. Not a total popcount of everything, but lots of little popcounts for every individual byte to determine the neighborhood count in GoL. The following ...
829 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. ...
367 views

### Mockup in C of hardware implementation for multiplication of signed integers

I challenged myself to implement multiplication of signed integers using only +, -, >>,...
482 views

### Binary multiplication on elliptic curves in C++

I wrote a function in C++ which uses binary multiplication (a form of binary exponentation): ...
1k views

### Calculate XOR of many consecutive and non-consecutive numbers

question: answer(start,length) #start is the starting number of the matrix #length is number of rows. example 1: answer(0,3) ...
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### Divide group of numbers into two groups of which the sums are equal

I have a piece of code that divides a group of numbers into two groups of numbers of which the sums are equal. I created this because of a Stack Overflow question: For example: {10,15,20,5} will ...
143 views

### Given bit strings, perform a bitwise addition

I'm looking for code-review, optimizations and best practices. This code is a Java adaptation of code on geeksforgeeks.org. Please verify if space complexity is $O(n)$ where n is number of bits, and ...
516 views

### Assembly: Sum up the single bytes of a 32bit-register to a checksum

Exercise description: "Write a program that takes a double word (4 bytes) as an argument, and then adds all the 4 bytes. It returns the sum as output. Note that all the bytes are considered to be of ...
467 views

### Bit manipulation tool set

I made a tool set to facilitate bit manipulation as follows. Any comments are welcome, be it about the interface design, the implementation, or even the naming. Also, I want to make sure that the tool ...
154 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 ...
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### Addition of two IEEE754-32bit single precision floating point numbers in C++

I made a C++ program which takes a list of triplets with S.No. from a text file, where the triplet, i.e. a,b,c correspond to a+b=c (addition done using float data type). Now I convert a and b from hex ...
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### Number of right cyclic shifts to give the biggest number

I am preparing to coding interview and I met this task today: You are given 30-bit unsigned integer N. A right cyclic shift of N by K bits is the result of performing a right cyclic shift of N by one ...
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### Function for splitting an integer into smaller values

This is the function I've implemented in an answer to this question. I've tried to make this as simple and idiomatic as possible, using C++11. Could this still be improved in any way? ...
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### 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 ...
290 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 ...
129 views

### Toggle four relays on/off based on bitmap stored in uint8_t

I am using a one-byte bitmap to control four relays. I am writing a function which will take the bitmap stored as uint8_t, look to see which bits are set/cleared, ...
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### Emulating __uint128_t

I developed a lot of code locally with __uint128_t only to find out that it is not available on the target platform. I am now trying to write my own struct that ...
239 views

I've made this simple function for reading N bits from an unsigned char* (with a possible offset) and I'm willing to share it here, get a review, suggestions for ...
959 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 ...
604 views

### Finding binary gap in Java

I want to know the performance of my code for following problem description. For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 529 has binary ...
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### Parsing an IP address (Bit manipulation)

Given a string representing of an IP address, such as "127.43.23.59", return a 32 bit integer representation of this string. The 32 bit integer is separated into four bytes, where each byte is one of ...
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### Network byte order to host byte order

While doing a little project involving sniffing packets, I found myself programming a cross platform network to host byte order and host to network byte order, this is my first time developing a ...
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### 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 <...
542 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 ...
247 views

### Binary permissions system with bitwise operators + properties

I've written a simple permissions system that I need to be rather fast, yet useable by other developers who primarily use Java. Is a bitwise permissions system with properties a good compromise. Any ...
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### PWM wave generation

This code takes a integer x of range [0,127] as input, returns an array of four 32-bit integers, with x bits set. I'm trying to ...
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### Byte-to-binary conversion function

My implementation of a binary-to-bits converting function: ...
180 views

### Finding the 'Minimum' AND of all the possible subsets of a set

The subset size should be greater than or equal to 2. How can I speed up this code? ...
328 views

### Print Bits Part III

The last question I have been playing around with is a right rotate. I think it is also called a barrel roll. Please post if you have a better solution please post. I am still learning the art of bit ...
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### 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 ...
110 views

### Compact Braille lookup

A related question got me thinking about a compact Braille dictionary. It certainly would be easier with Int16 or string but was going for most compact. I don't think there is a case insensitive char ...
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### Print the next smallest and next largest number that have the same number of 1 bits in their binary representation

Given an integer , print the next smallest and next largest number that have the same number of 1 bits in their binary representation. How can I improve this? ...
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### Testing for divisibility of numbers - follow-up

(Here is the follow up question) I had another go at trying to speed up my program described in my previous question. JS1's answer was particulary helpful and now my code is only about 20% slower ...
671 views

### Implementing binary output to a file in C++11

I would like to have a class which supports outputting bits into a file. This is what I came up with but I fear there are many poor decisions. Should I inherit from a ...