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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31 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:
...
4
votes
1answer
36 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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vote
0answers
27 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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vote
3answers
207 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 ...
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0answers
18 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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vote
3answers
40 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 ...
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3answers
222 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
40 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 ...
9
votes
1answer
194 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 ...
3
votes
1answer
58 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 ...
7
votes
1answer
270 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 ...
2
votes
1answer
207 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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vote
2answers
76 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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7
votes
2answers
60 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 ...
4
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0answers
42 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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2answers
42 views
3
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3answers
84 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 ...
4
votes
1answer
93 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
72 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 ...
10
votes
2answers
102 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 ...
4
votes
1answer
172 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 ...
2
votes
0answers
92 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 ...
3
votes
1answer
42 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 ...
3
votes
5answers
82 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, ...
4
votes
2answers
404 views
Java conversion of base 16 to base 64
I wrote a solution in Java to solve the problem here. I use BigInteger to convert first from base 16 to base 10, then base 10 to base 64.
This seems quite ...
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1answer
149 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 ...
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votes
3answers
78 views
Testing if the binary representation of an integer has an odd number of ones
The fn odd_ones(x: u32) -> bool function should return true when x contains a odd number ...
7
votes
2answers
127 views
All arithmetic operator functions (+, -, *, /, %) coded only using bitwise operators in C
Here's all the functions in C that does all the arithmetic operators without using arithmetic operators themselves, mostly using bitwise operators. Recursive functions and comparison operators are ...
2
votes
1answer
51 views
Three ways to read a number for a BitInputStream
I'm trying to learn how to write more readable code without introducing easily avoidable performance killers.
This is part of a BitInputStream Java class I'm ...
3
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1answer
36 views
PWM wave generation
This code takes a integer x of range [0,127] as input, returns an array of four 32-bit integers, with x bits set.
I'm trying to ...
3
votes
1answer
62 views
Testing for divisibility of numbers - follow-up
(Here is the follow up question)
I had another go at trying to speed up my program described in my previous question.
JS1's answer was particulary helpful and now my code is only about 20% slower ...
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votes
2answers
82 views
Program to test for divisibility of numbers
(EDIT: here is the follow up qusetion)
Using this program to test for the smallest number where its permutations or itself is divisible by 10 or less numbers is twice as slow as the fastest program I ...
5
votes
3answers
334 views
Finding nearest power of 2
I have the following simple program which calculates and returns the nearest power of 2 of a given number. Because I use increments and decrements to find the closest power, this takes a very long ...
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0answers
140 views
Read bits, write bits data to arbitrary position in char array
I created functions to read bit data from arbitrary bit position of a char array to long long int, and I also created a function ...
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1answer
131 views
Bitmask type to perform binary operations
Without any specific implementation details, how would you create a bitmask type that wraps binary arithmetic into something easy to read? Ideally, this would be used with an ...
1
vote
1answer
123 views
“Flipping bits” Python implementation
Problem Statement
You will be given a list of 32 bits unsigned integers. You are required to output the list of the unsigned integers you get by flipping bits in its binary representation (i.e. ...
7
votes
1answer
99 views
Return Y integer with same bit sets as X & having | X - Y | minimum value
I happened to come across one question:
Given an integer 'x' (Only positive), write an algorithm that returns
integer 'y' such that it has the same number of bits set as 'x' and is
not equal ...
3
votes
1answer
72 views
Code Chef problem COOKMACH
Firstly, I got the solution for this question in CodeChef, but I noticed one thing which still confuses me. This was the code which was accepted as correct.
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6
votes
1answer
125 views
Reading bits from a stream from least to most significant
For a recent project I was in need of excessive bit manipulation. Specifically, I had to write to or read from a variable number of bits up from the least significant bit towards the most significant ...
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votes
3answers
115 views
Performing add/delete/count operations on a list
Problem Statement (HackerRank)
You have a list of integers, initially the list is empty.
You have to process Q operations of three kinds:
add s: Add integer s to your list, note ...
4
votes
2answers
606 views
Division without multiplication, addition or division
In context of preparing for a coding interview, I gave the division problem a go using Java. This is what I came up with. It's a little bit different to other solutions I've come across the interweb.
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5
votes
8answers
2k views
String reversal, capitalize vowels, lowercase consonants
This was a portion of a skills test given to me by a company. The task was to write a method that takes a string, reverses it, and sets the vowels as capitals and consonants to lowercase. I was also ...
3
votes
3answers
633 views
Number of right cyclic shifts to give the biggest number
I am preparing to coding interview and I met this task today:
You are given 30-bit unsigned integer N. A right cyclic shift of N by K bits is the result of performing a right cyclic shift of N by one ...
3
votes
3answers
325 views
Mockup in C of hardware implementation for multiplication of signed integers
I challenged myself to implement multiplication of signed integers using only +, -, ...
3
votes
1answer
84 views
Encoding variable-length quanties for MIDI
I was reading about the MIDI spec and I challenged myself to implement a function to convert an int32 to a variable length quantity uint32.
I didn't look it up or ...
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vote
1answer
289 views
Pixel bit-wise LSB extraction to byte array
I wrote the following code below to extract the least significant bit (LSB) of each pixel and store it into a byte[] array. I was wondering if Java has a more ...
5
votes
2answers
233 views
Verifying validity of Intel.hex file records
I have a class called FirmwareFile which represents and Intel HEX format file. The file is constructed with the name, build time and build date, at a later point ...
4
votes
1answer
139 views
Printing lines in a file, filtering by the first column
I am setting up a project which involves a lot of data analysis, each data point represented by a line in a large text file. In order to test for certain types of data, I added a tag to each line (It ...
4
votes
3answers
135 views
Bitstream reader
I have a program which reads and analyses MPEG-TS files. I've been using gperftools to identify hotspots and optimize them, and 45% of all samples at this point are in my main bitstream reader ...
10
votes
3answers
155 views
Fastest sum of absolute values of 32 differences
A long should be treated as a list of 32 unsigned numbers, each of them just two bit long. So 0x1234F... represents
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