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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Check if a number is divisible by 3, efficiently
Efficient way to check if a number is multiple of three. Looking for code review, best practices and optimizations.
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1answer
41 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
98 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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3answers
127 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
350 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
253 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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2answers
58 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
51 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
938 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
93 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
383 views
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4answers
1k 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
130 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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0answers
32 views
Could this ROM reader be faster and/or smaller?
I've been practicing arduino programming for a few weeks now having become confident in reading and writing to pins so I decided to take it a step further and do a serious project that does both, so ...
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2answers
109 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
132 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
1k 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
135 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
126 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 ...
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1answer
222 views
Missing element from array (D&C) - code design/aesthetic improvement
I am trying to implement in C/C++ a 'classical' Divide and Conquer algorithm which solves the following problem "Given an array of n-1 numbers (int) from 0 to n, find the missing number".
I am using ...
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1answer
104 views
Bitwise Logic optimization
I should be able to figure this out on my own, but I can't seem to wrap my head around how to optimize this set of logic for interpreting the existence of URL parameters.
Below is my code:
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1answer
99 views
Color fading function
I found this old color fading function in my snippets folder and would like to implement it to one of my projects. It can be used to fade one color to another. It's a very long one-liner:
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2answers
699 views
Speed up a program to find the minimum Hamming distance
I have a solution to the puzzle at https://kattis.csc.kth.se/problem?id=codes.
What can I do to make my algorithm much much faster? What the algorithm does is take an N×K matrix and search for the ...
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5answers
910 views
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 ...
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1answer
265 views
JavaScript xor function
I made simple JavaScript xor function. It accepts string, numeric array and mixed array (char, string, num) as params. It returns string or an array.
Returning an array is a must!. All numbers are ...
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1answer
122 views
Simplify bit flags checking code
Please help make this code more cleaner. It's a part of window procedure that notifies my renderer before client area of window resized.
I need to check two combinations of bit blags: some of them ...
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1answer
525 views
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 ...
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1answer
54 views
What are these bitwise operations doing? [closed]
I found a snippet of code on the PHP manual which packs 64 bit integers. APparently this is necessary because pack() always treats numbers as 32 bit integers even ...
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2answers
993 views
Spotify's “Reversed Binary Numbers” Problem [closed]
I wrote some Java code for Spotify's Reversed Binary Numbers puzzle and I tested it on my machine and I am almost positive that it behaves as expected. However, when I send it to puzzle AT spotify.com ...
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1answer
335 views
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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3answers
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Base-36 encoding of a byte array
After posting a question about Alphanumeric Hash generation on StackOverflow, the most helpful answer was to change the conversion method from pulling 5-bit chunks of a binary hash value, to instead ...
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1answer
131 views
What specific optimizations can be made to this BitArray class, and how can they be implemented?
Here is the current code for the BitArray class needing optimization (implemented on big integers):
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1answer
510 views
speeding up an algorithm that find patterns in a growing collection
I want to find a way to speed up this code.
if you look at the condition of If calculated Then in the code below, this is what slowing down the code.
While the ...
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3answers
735 views
How to manage a bit array with C programming langage?
I'm training a bit with C, and I'm trying to build a bit array. I would like to have some comments about my code, because I'm not sure that it's the best way to do it.
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5answers
611 views
Counting the number of bits of a positive integer
How can I improve this code for counting the number of bits of a positive integer n in Python?
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1answer
362 views
BitVector Class: Performance
Lately, I've been reading up on the Common Language Infrastructure's data formats. As a result, one thing it mentioned is some of the data is stored in a BitVector.
I hadn't ever used a BitVector ...
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1answer
349 views
Jon Bentley's bitmap sort implementation
I've implemented Jon Bentley's bitmap sorting algorithm from Column 1 of his Programming Pearls book. This code supports user-defined integer range (works from ...
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3answers
791 views
Bit rotations exercise
I'm studying C on K&R and I solved exercise 2.08:
Write a function rightrot(x,n) that returns the value of the integer x ...
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8answers
8k views
Fastest way to clamp an integer to the range 0-255
I'm working on some image processing code that can generate pixel values outside of the normal range of 0 to 255, and I'd like to clamp them back into the valid range. I know that there are saturating ...
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1answer
236 views
Print Bits Part II|: Coding Feedback Wanted
The last question I have been playing around with is a right rotate. I think it is also called a barrel roll. Anyways if you have a better solution please post. I am still learning the art of bit ...
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131 views
Print Bits Part II: Coding Feedback Wanted
Does anyone have a shorter more simple way of doing this?
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8answers
3k views
Copying 80 bytes as fast as possible
I am running a math-oriented computation that spends a significant amount of its time doing memcpy, always copying 80 bytes from one location to the next, an array of 20 32-bit ints. The total ...
