Are bit operations quick?

Posted by flashnik on Stack Overflow See other posts from Stack Overflow or by flashnik
Published on 2010-05-10T22:10:06Z Indexed on 2010/05/10 22:14 UTC
Read the original article Hit count: 296

Filed under:

bit-manipulation

|

c++

|

Performance

|

storage

I'm dealing with a problem which needs to work with a lot of data. Currently its' values are represented as unsigned int. I know that real values do not exceed some limit, say 1000. That means that I can use unsigned short to store it. One profit is that it'll use less space. Do I have to pay for it by loosing in performance?

Another assumption. I decided to store data as short but all calling functions use int, so I need to convert between these datatypes when storing/extracting values. Wiil the performance lost be dramatic?

Third assumption. Due to great wish to econom memory I decided to use not short but just 10 bits packed into array of unsigned int. What will happen in this case comparing with previous ones?

© Stack Overflow or respective owner

Related posts about bit-manipulation

Find three numbers appeared only once using bit manipulation

as seen on Stack Overflow - Search for 'Stack Overflow'
In a sequence of length n, where n=2k+3, that is there are k unique numbers appeared twice, how to find the three unique numbers that appeared only once using bit manipulation? for example, in sequence 1 1 2 6 3 6 5 7 7 the three unique numbers are 2 3 5. >>> More
Learning C bit manipulation

as seen on Stack Overflow - Search for 'Stack Overflow'
I didn't know any better name for a title of the question. For ex: on one of my previous questions one answered ((a)-(b))&0x80000000) 31 - this is kind of a too advanced for me and i can't really get what it means. I am not looking just for an answer of that, but i need someone to tell me some… >>> More
Bit manipulation, permutate bits

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi. I am trying to make a loop that loops through all different integers where exactly 10 of the last 40 bits are set high, the rest set low. The reason is that I have a map with 40 different values, and I want to sum all different ways ten of these values can be multiplied. (This is just out of… >>> More
bit manipulation in java

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a fragment of bytes in a byte[]. The total size of the array is 4 and I want to convert this into a positive long number. For example if the byte array is having four bytes 101, 110, 10, 1 then i want to get the long number represented by binary sequence 00000000 00000000 00000000 00000000… >>> More
Doing 64 bit manipulation using 32 bit data in Fixed point arithmetic using C.

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am stuck with a problem. I am working on a hardware which only does support 32 bit operations. sizeof(int64_t) is 4. Sizeof(int) is 4. and I am porting an application which assumes size of int64_t to be 8 bytes. The problem is it has this macro BIG_MULL(a,b) ( (int64_t)(a) *… >>> More

Related posts about c++

Which C++ book shold I get between "C++ Primer" vs "C++ Primer Plus"

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to learn C++ by using Vim and MinGW as compiler. I'm interesting at "C++ Primer (4th Edition)" and "C++ Primer Plus (5th Edition)" but I don't know how about it different. It has no book store that I can review those books, so I want to know, what is the different between those book and which… >>> More
C++ : C++ Primer (Stanley Lipmann) or The C++ programming language (special edition)

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a Computer Science degree (long2 time ago) .. I do know Java OOP but i am now trying to pick up C++. I do have C and of course data structure using C or pascal. I have started reading Bjarne Stroustrup book (The C++ Programming Language - Special Edition) but find it extremely difficult esp… >>> More
I need help on my C++ assignment using MS Visual C++

as seen on Stack Overflow - Search for 'Stack Overflow'
Ok, so I don't want you to do my homework for me, but I'm a little lost with this final assignment and need all the help I can get. Learning about programming is tough enough, but doing it online is next to impossible for me... Now, to get to the program, I am going to paste what I have so far. This… >>> More
Managed c++ std::string not accessible in unmanaged c++

as seen on Stack Overflow - Search for 'Stack Overflow'
In unmanaged c++ dll i have a function which takes constant std::string as argument Prototype : void read ( const std::string &imageSpec_ ) I call this function from managed c++ dll by passing a std::string. When i debug the unmanaged c++ code the parameter imageSpec_ shows the value correctly… >>> More
The Definitive C++ Book Guide and List

as seen on Stack Overflow - Search for 'Stack Overflow'
After more than a few questions about deciding on C++ books I thought we could make a better community wiki version. Providing QUALITY books and an approximate skill level. Maybe we can add a short blurb/description about each book that you have personally read / benefited from. Feel free to debate… >>> More