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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71 views

Speed optimization for transparent gradient blend algorithm

The following algorithm works correctly for the purposes that I need, which is to set the top side of an image with a transparent gradient blend. Any tips to optimize it for speed? ...
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2answers
75 views

Binary to decimal number converter

Here I am doing some exercises for my studies with Python. This is a binary to decimal number converter (currently restricted to that). These are the very first steps, so there is no error handling. ...
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2answers
75 views

Computing pairwise bitwise OR in a list of bit-strings

I am trying to solve this problem using Clojure: You are given a list of \$N\$ people who are attending ACM-ICPC World Finals. Each of them are either well versed in a topic or they are not. ...
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1answer
107 views

Gray codes addition

As some of you know, I have been working with Gray codes and am trying to design a good gray_code class in modern C++. I will end up posting several parts of the ...
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1answer
59 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 ...
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2answers
136 views

Embedded C# bitpacked arrays to low-level STM32F4 driver for GE G35 RGB LED Christmas tree light

I'm going to be opensourcing some code I'm working on. I don't need help with the code, I just want to make sure my code is readable and my comments make sense. I have a knack for the esoteric. ...
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0answers
59 views

Saving bytes instead of objects to write smaller files

This question is about reducing the size of files saved to disk in an infinite world 2D mining game. I finally added code to my game to save and load distant chunks instead of keeping all of them ...
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2answers
63 views

Count bits that differ between integers X and Y

I'm trying to solve the following problem : You are given two integers, X and Y. Calculate the number of bits that will be changed in order to convert integer X to integer Y. Here is my ...
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1answer
176 views

Logical shift with signed numbers

I am going through the Coursera course The Hardware/Software Interface and because it has already ended, I would not be able to get any feedback on the code. The assignment is: LogicalShift: ...
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2answers
119 views

Lossy packing 32 bit integer to 16 bit

I am working on the lossy 16 bit representation for 32 bit integers that catches all 32 bit range with precision depending on absolute value. My idea is to store integer ...
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1answer
380 views

Steganography for images

For a school project I'm working on a small library to do steganography. I've just finished the first method of steganography and thought I'd get some feedback. This steganography method works by ...
7
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2answers
123 views

Array-like container for uints shorter than 8 bits (Rev 1)

This is a follow-up to Array-like container for uints shorter than 8 bits In short: The PackedBitfieldArray should be a kind of container for packed (unsigned) ...
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1answer
137 views

Array-like container for uints shorter than 8 bits

Follow-up: Array-like container for uints shorter than 8 bits (Rev 1) First of all: yes, I need this kind of array to generate data for a piece of hardware, and it must be stored and manipulated ...
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3answers
1k views

Diamond in the rough! Finding Gems in the rocks

Recently a question was asked that solved a hackerrank problem: Counting gems amongst the rocks The description of the challenge is: John has discovered various rocks. Each rock is composed of ...
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1answer
75 views

Bitwise operation to get the weekday name

The function days_name receive a val (string) corresponding to weekdays in hexadecimal. ...
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2answers
103 views

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 ...
7
votes
1answer
141 views

Hexadecimal to RGB conversion

I am trying to convert hex to rgb, and rgb to hex. My current code doesn't seem optimal, and there is an issue with 0's in the hexadecimal. What do you think about the overall quality of this code? ...
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2answers
569 views

Validating UTF-8 byte array

I'm writing a validator function that receives a byte[] and checks whether it represents a valid UTF-8 byte sequence, according to this table. Is my approach ...
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4answers
253 views

BitShift code compacting

I'm new to Java programming and am really enjoying it. I made a bitshift program, but I think it's too long. I expect the program to: Let users input the number and degree to be shifted Specify if ...
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1answer
246 views

Implementing Karatsuba Multiplication Algorithm in Python

I am trying to implement Karatsuba multiplication algorithm for binary (base 2) numbers. A requirement is that the intermediate / final results must also be in binary so as to assist in educative ...
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3answers
387 views

Finding the largest of a series of numbers being XORed

I'm working on solving a problem involving finding the largest of a series of numbers being XORed. This is the actual problem: Xorq has invented an encryption algorithm which uses bitwise XOR ...
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3answers
104 views

Check if bit is only set once in a vector of int

I have a vector of uint16_t and I want to check if there is a bit which is only set in one vector. I then get its position within the vector as well as from the ...
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2answers
201 views

Why are these functions slower than BigInteger's included methods?

I tried writing alternative functions to Java's BigInteger.add(BigInteger.ONE), BigInteger.add(BigInteger), and ...
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1answer
95 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? ...
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3answers
1k views

Converting an IP

I've written a DNS tool in Node and would like to know if there's a better and more efficient way of handling the conversion from an IP to a long. I'm not too good at bitwise just yet and would like ...
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247 views

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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2answers
62 views

Is there a more optimal way to approach some of these bitwise functions?

I completed some bit manipulation exercises out of a textbook recently and have grasped onto some of the core ideas behind manipulating bits firmly. My main concern with making this post is for ...
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1answer
87 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 ...
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2answers
109 views

Implementations of rotate, shift, XOR, NOT and AND

I am going through the example of SHA256 over at Wikipedia and wanted to make sure I understood all the operations of the manipulation math before trying to actually attempt the implementation itself. ...
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Displaying data as binary in C with bitmasks

I wrote a program to display data in memory as binary and it worked. (It gave me immense sense of satisfaction and joy to see this work. I guess this happens to newbies who are just testing the ...
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4answers
181 views

Arithmetic or logical right shifts

Is this code correct? Is there any major improvement I can ad in terms of number of operations? ...
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8answers
10k views

Efficiently checking if a number is divisible by 3

I'm looking for code review, best practices and optimizations. ...
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2answers
160 views

Fastest / most efficient random bit indexing in Python

Using Python/Cython, I am trying to construct an efficient way to index boolean values. I have been trying to use the bitarray and/or bitstring packages to construct a fast, non memory intensive way ...
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1answer
157 views

Optimizing multiplication of two polynomials in GF(2^32)

I have the following method for multiplying two polynomials in GF(232): ...
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695 views

Integer square root in x86 assembly (NASM)

This program calculates the square root of an unsigned 32-bit number with some bit fiddling to get a very close approximation, then one iteration of the Babylonian method to get an exact value. I ...
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3answers
449 views

Bit exchange operation

I have been working on a certain task these days and after several hours of torture, I have done it! However, I believe the code that I have "crafted" is quite difficult to be understood and to be ...
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2answers
574 views

Bit packing and unpacking

I needed a variadic function to pack and unpack bits into integer types. This is my first attempt: ...
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105 views

Decomposing bitfield with Haskell: is recursion the only way to do this?

Here's a program to take a bitfield like 7 and decompose it into the flags [1,2,4]. Ignore that the algorithm for doing this doesn't use bit shifting/is stupid. Problems: it seems like I have to have ...
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1answer
60 views

Eliminating repetitiveness in code to test hash functions

I usually take my school code as a playground to mess around with things. I was given a bunch of premade hash functions and had to test their output and find when they reach a specific lower range. ...
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5answers
1k views

Setting and getting bits in C

I am just starting to get my feet wet with C; and am rather enjoying myself in doing so. This is sort of a follow up to my last question here. I am posting this ordinate to hopefully getting some ...
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1answer
115 views

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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4answers
931 views

Boolean expression complexity and bitwise operators

Given this kind of code: ...
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2answers
809 views

Gaussian blur - convolution algorithm

My program uses graphics convolution, an algorithm that processes pixels to make them round, soft and blurred. This particular algorithm is well-known, but its slowing down the operation of the whole ...
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4answers
4k views

Counting number of 1's and 0's from integer with bitwise operation

Is there a better way of doing this? ...
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2answers
144 views

Function for reading bits

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 ...
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2answers
141 views

Copy and bit-invert ints in an std::vector

I want a second copy of an std::vector in which all elements are inverted, e.g. 0x01 in the first vector should be ...
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1answer
142 views

Take all the bits in a number and shift them to the left end

I wrote this program which takes all the bits in a number and shifts them to the left end (for example: 01010110 --> 11110000). It's and exercise from a book. It works, but it seems to be very ...
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3answers
2k views

Split a long integer into eight 4-bit values

It's an exercise from a book. There is a given long integer that I should convert into 8 4-bit values. The exercise is not very clear for me, but I think I understood the task correctly. I googled ...
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1answer
208 views

10x10 bitmapped square with bits

This program prints out a 10x10 square and uses only bit operations. It works well, but I don't like that global array. Can you tell me if the code is proper or not? ...
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1answer
153 views

Playing with bits using Java

How can I optimize the following class? prepareSharing packs bits on left and prepareMask counts the required bits for encoding ...