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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7answers
335 views
Changing element visibility based on multiple checkbox states
I am writing a script in JavaScript & HTML and have some optimization problems. In the for, loop I check a variable named ...
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2answers
87 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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votes
2answers
100 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
110 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. ...
10
votes
1answer
119 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 ...
3
votes
1answer
70 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 ...
10
votes
2answers
160 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. ...
8
votes
1answer
146 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 ...
6
votes
2answers
68 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 ...
9
votes
1answer
182 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: ...
8
votes
2answers
120 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 ...
11
votes
1answer
436 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
votes
2answers
125 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) ...
11
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1answer
138 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 ...
17
votes
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 ...
2
votes
1answer
83 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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3
votes
2answers
108 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
156 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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votes
2answers
809 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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votes
4answers
265 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 ...
6
votes
1answer
297 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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votes
3answers
394 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
...
8
votes
3answers
105 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 ...
5
votes
2answers
250 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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votes
1answer
98 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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votes
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 ...
3
votes
2answers
254 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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votes
2answers
63 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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votes
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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votes
2answers
123 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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vote
2answers
22 views
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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votes
4answers
256 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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26
votes
8answers
11k views
Efficiently checking if a number is divisible by 3
I'm looking for code review, best practices and optimizations.
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votes
2answers
169 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 ...
7
votes
1answer
170 views
Optimizing multiplication of two polynomials in GF(2^32)
I have the following method for multiplying two polynomials in GF(232):
...
8
votes
3answers
869 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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votes
3answers
464 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
629 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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votes
2answers
114 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 ...
5
votes
1answer
61 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. ...
14
votes
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 ...
4
votes
1answer
120 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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votes
4answers
987 views
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votes
2answers
920 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 ...
13
votes
4answers
4k views
Counting number of 1's and 0's from integer with bitwise operation
Is there a better way of doing this?
...
3
votes
2answers
145 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 ...
2
votes
2answers
148 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 ...
2
votes
1answer
143 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 ...
5
votes
3answers
3k 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 ...
11
votes
1answer
212 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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