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Code Review

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.

257 questions
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Generating a bitboard with all possible bishop moves [on hold]

I am in the middle of programming a chess ai. I have run into a problem when trying to calculate all possible diagonal moves for the bishop. I think the problem lies within the function: ...
3
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1answer
37 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
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3answers
232 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: <...
2
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5answers
166 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
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2answers
88 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
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1answer
27 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
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2answers
62 views

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

Here is my code: ...
4
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2answers
107 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
191 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
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1answer
69 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
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1answer
58 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
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1answer
49 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
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2answers
98 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
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1answer
74 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
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1answer
113 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 ...
4
votes
3answers
174 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
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4answers
135 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
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2answers
106 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
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0answers
67 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
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1answer
62 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
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2answers
514 views

Bitwise comparison of any structure

What I tried to do is compare arbitrary structures independent of the == operator implementation. ...
5
votes
1answer
106 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 ...
4
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3answers
258 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
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1answer
149 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 ...
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2answers
1k views

Reversing the bits of a 32-bit integer

Here is my code: ...
6
votes
1answer
308 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
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1answer
52 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
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2answers
132 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,...
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2answers
58 views

The program that reverses bytes in two distinct ways (in C++)

Will be grateful if anyone would reasonably comment on my code. I am interested in the style only. If there will be any comments which are not related to the style I am glad to read them as well. <...
2
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2answers
228 views

Hamming distance

I am wondering how I can improve the runtime of this code. I was solving this task at leetcode, and came up with this solution. But I got the result that my runtime is 88 ms, which beats a bit more ...
3
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1answer
412 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 ...
3
votes
3answers
571 views

Associating a name with each bit in a bitmask

I have the following code: ...
5
votes
5answers
303 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 ...
6
votes
2answers
354 views

Variable integer encoding

There is a varint encoding, which I call LEP64 (Little Endian Prefix Max 64-bit). Basically, the first byte of the encoded value tells us, how many bytes follow (needed bytes encoded in unary coding, ...
6
votes
1answer
346 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 ...
6
votes
1answer
100 views

Take first 12 bits of a number if longer than 12

I need to only take first 12 bits of a number if its longer than a 12 bit number and convert it to a decimal number. So if 7000 is entered than it will return 3500. I also print out the binary form of ...
1
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1answer
61 views

Bit pattern to console output

This function will draw a card in the console ...
1
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0answers
71 views

Sending data from UART to microcontroller via AT89C2051 functioning as a UART/SPI bridge

I have an unusual setup. I have an AT89S52 microcontroller in which its UART is used by the PC. I needed a way to make a second UART based device work with it, so what I decided to do was make a UART ...
2
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0answers
146 views

Binary addition in VB.net

It starts by taking two user input from the console and putting them into strings. I then pad them to get them to the same length. I get the length of the num1 and assign it to the integer len. I then ...
5
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3answers
295 views

Fast bitswap in assembly

Can the following code to swap two bits be optimized? ...
2
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2answers
482 views

Space and time efficient Algorithm for generating prime numbers

I have developed an algorithm for generating prime numbers (which turns out to be an optimized version of the Sieve of Eratosthenes) by reducing the space by a factor of 64. ...
6
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3answers
84 views

Minimal stack from unsigned int to track boolean values wtih bits

This grew out of a need to track sequential ctrl+shift+Left/Right-arrow keypress events on a gtk editor. It is a small stack implementation for boolean values (for <...
3
votes
1answer
82 views

Gradient noise class based on Simplex noise

Here's a seedable 2D and 3D gradient noise class in C# that I wrote based on Simplex noise. Seems to work properly (even though it's highly experimental). I'm looking for tips to improve the quality ...
6
votes
1answer
225 views

YouTube playlist steganography: hide secret messages inside YouTube playlists

I have created this repo on GitHub and I have shown how this software works through a video. If you have time, please visit the repo and read the files. I'll post some relevant snippets below, but if ...
6
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2answers
320 views

Shifting an 128-bit integer consisting of four 32-bit integers

For a little project of mine I have written two versions for shifting a 128-bit unsigned integer consisting of four 32-bit unsigned integers in x86 assembly. I cannot really decide which is better in ...
5
votes
2answers
258 views

Thread-safe BitArray

Notes: supports 64-bit platforms only ulong used where negative values make no sense library functions are assumed to be correct (whether they actually do what I ...
1
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2answers
244 views

Musical graph algorithm, with an inlined lookup helper function

I am working with bit strings in clojure. My question is less about performance and more about how one should go about it (in particular see the last inlined version) The tonnetz-array represents an ...
15
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1answer
3k views

Compressing a 'char' array using bit packing

I have a large array (around 1 MB) of type unsigned char (i.e. uint8_t). I know that the bytes in it can have only one of 5 ...
2
votes
4answers
67 views

Assembler-program which reverses the content of EAX

Following exercise: "Write a program that takes a number (of size 4 bytes) x as input, and then reverses all the bits of x, and outputs the result. By reversing all bits we mean that the bit ...

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