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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Compute the XOR of all the elements in the upper left triangular of a square matrix
Given a dimension \$D\$. We generate a \$D\times D\$ matrix with elements that start from \$0\$. For example, if we're given a dimension \$4\$ this is what our matrix looks like:
$$
\begin{bmatrix}...
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1answer
63 views
Hackerrank Sum vs XoR
I'm in the process of improving my coding style and performance hence I decided to delve into bit manipulation on Hackerrank. I thought the question was straight forward but on large input, my ...
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1answer
64 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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3answers
462 views
Counting the number of “on” bits in an int
Here is some code I wrote as a solution to Programming Exercise 15.3 in Stephen Prata's C Primer Plus, 6th Edition. It is probably worth pointing out that the title of the chapter is Bit Fiddling. The ...
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1answer
57 views
K&R 2.6 Exercise setbits(x,p,n,y) function
Write a function setbits(x,p,n,y) that returns x with the n bits that begin at position <...
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1answer
442 views
Xoring in constant time in Java
I was inspired by this answer and the explanation and decided to support negative numbers. While testing, I noticed that the solution didn't handle the case with one number in the given range. A quick ...
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5answers
88 views
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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votes
2answers
824 views
Maximize result of bitwise AND
This was the problem from "30 Days of Code" on Hackerrank:
Given set \$S = \lbrace{1,2,3,\dots,N}\rbrace\$, find two integers \$A\$ and \$B\$ (where \$A \lt B\$), from set \$S\$ such that the ...
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35 views
Getting TLE for SPOJ Bitplay challenge program
I have tried a naive way to solve this problem:
Given a even number N (N ≤ 109) and an integer K, you have to find the greatest odd number M less than N such that the sum of digits in binary ...
3
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2answers
36 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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4answers
854 views
Return the next power of two
Given an unsigned integer \$N\$, I want to return \$P\$ with \$P\$ being a power of two such that \$P \ge N\$.
Examples:
1 -> 1
2 -> 2
3 -> 4
5 -> 8
The goal is to provide a very fast ...
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30 views
Bit twiddling utils for Int and Long classes
I added some bit twiddling utils to Int and Long classes in Scala but I have highly duplicated code. Is there a way to DRY this?
...
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2answers
236 views
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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1answer
259 views
Start an EventHandler in different Thread
I just stumbeled accross some code and I would do it in a different way. Since I am quite new to programming, I just wanted to know if I understand it right.
Original Code:
...
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1answer
48 views
ANDing ints in Java [closed]
Is there any better way than doing:
if ((newState & InputState.DEFAULT) == InputState.DEFAULT)
?
My InputState.class defines static int variables to the ...
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votes
2answers
208 views
Codility binary gap solution using regex
This is how I solved the binary gap problem:
Find longest sequence of zeros, bounded by ones, in binary representation of an integer.
However, it seems to be different from the answers out there. Is ...
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2answers
267 views
K&R 2-7 - Invert a bitfield from a number
This is my solution to the Exercise 2-7 of K&R C book. The assignment is:
Write a function invert(x,p,n) that returns x ...
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1answer
54 views
Implementing checksum add without carry in C
I need to write a function in C which performs a checksum using the rule "add without carry". As I understand it, the "add without carry" concept is equivalent to the bitxor operator and given that ...
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1answer
176 views
Bit shifting and masking
I was wondering if someone could review this simple bit of code that originally was in C++, but now converted to C# as practice in using bit-shifting and creating a sort of a quasi-array functionality....
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votes
3answers
101 views
A simple assembly program to count the number of ones in a register
I made a simple assembly program to count the number of ones in a register. Since this is basically my first ever, I would like to hear what I can improve or if there are some major flaws in this one:
...
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2answers
139 views
Packing and unpacking bits (2)
Part 1 here.
I improved my code from my previous question (linked above).
...
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2answers
187 views
Packing and unpacking bits
Part 2 here.
I wrote this class for packing data.
Would it benefit from being named BitPacker rather than BitStream (and change write/read to pack/unpack), or it works as is?
How can I improve it? ...
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1answer
41 views
Using JavaScript-bitwise AND and -bitwise NOT for setting a number to 0
Obviously is the XOR-operator is used in low-level programming-languages used a lot for setting a value back to all bits 0.
For example:
11010 ^ 11010 => 00000
Brought my teacher to figuring a out ...
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5answers
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1answer
79 views
Bit string builder for Java
I have this Java class for building bit strings. The set of methods it provides resembles that of java.lang.StringBuilder.
See what I have:
BitStringBuilder.java:
...
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votes
1answer
52 views
LEB128 in Haskell
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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0answers
42 views
Convert tri-gram of type wchar_t to an integer type
I am trying to convert a tri-gram containing 3 characters of type wchar_t to an integer type (an uint64_t at the present time).
...
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3answers
2k 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 ...
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0answers
28 views
Implement “at” lens for Data.Map
I've been working on adding an operation like Data.Lens.At.at to Data.Map. This uses an extremely fast, extremely small, and ...
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3answers
63 views
Byte array to floating point such as FPE2 in Java
Apple's System Management Controller uses FPE2 and SP78 as floating-point formats.
While writing a Java library that that interfaces with the SMC, I ported someone's C function to convert read a FPE2-...
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3answers
263 views
Finding the fastest common prefix of 2 strings in Python
I'm comparing my algorithms, slice_prefix and bit_prefix, with existing ones to find the common prefix length of 2 strings as ...
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0answers
52 views
A bitwise common prefix algorithm in Python
Is my algorithm slow because it has problems? Or, is any bitwise common prefix solution not going to give me the performance I'm looking for?
After profiling my algorithm, I found that over 60% of ...
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1answer
220 views
Console app to teach bitwise operators
I'm creating a console app that has the purpose to teach you how to use C# bitwise operators. I have several classes which contain info about the different operators and I instantiate/add them in the ...
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votes
1answer
74 views
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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295 views
Calculating the results of bit operations
I have a simple program that calculates and outputs the results of all the bit operators. I'm planning to send it to my friend and to explain some stuff about them to him. Before I do that, I want to ...
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1answer
848 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 ...
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2answers
84 views
Concatenate three 16-bit integers in one 64-bit integer with C++
I am looking for an elegant alternative of the following code where wordXX contains always 16 bits:
...
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2answers
71 views
Portable byte order conversion
I'm trying to improve the portability of a file format converter, specifically to POSIX platforms other than Linux. I'd appreciate a review of the following functions used for converting between ...
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0answers
53 views
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 ...
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3answers
97 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 ...
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votes
1answer
109 views
Speeding up the generation all bit strings with Hamming distance one
I'm playing around with hypercubes. For this, I need to create its edge set. Specifically, the edge set is the set of all bit strings with Hamming distance 1. An important property is that I want to ...
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1answer
159 views
Saturated signed addition
So this a exercise from the book COMPUTERS SYSTEMS A PROGRAMMERS PERSPECTIVE
I need to add two signed numbers and in case it overflows or underflows return ...
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119 views
Simulation of image transfer over noisy channel
Following this question, I've tried to rewrite some core methods to avoid using String for bit operations, and I ended up using ...
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1answer
184 views
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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0answers
174 views
FUTABA SBUS serial communication in C++
I would like to reimplement the current Futaba SBUS protocol in ArduPilot for Navio+. It seems to be a relatively expensive protocol, so I changed the code from an existing git project and to make it ...
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1answer
45 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 ...
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votes
5answers
94 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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1answer
412 views
Remove elements existing in a list built from an enum
The objective of this code is to make the difference inbetween two lists of items, that is knowing which items are missing in the second list in regards to the first one.
The first list is built from ...
