SEARCH KEYWORD -- Bit operation


  Hexadecimal and long in Java

Today I encountered a hexadecimal operation problem when I was implementing a bit reverse function for integer type. Basically in the implementation, there is an operation which is to do the bit operation & between one long integer and a hexadecimal number 0x00000000FFFFFFFFF. I was expecting that the high 32 bits of the long integer will be zeroed. But unfortunately I didn't get the expected result. The basic implementation is: long num=0x00F0_0000; num = (num>>16) | (num<<16); ...

   Hexadecimal,long,Java,bitwise operation     2014-06-18 23:44:32

  32-bit vs 64-bit

I have knowledge on 32-bit vs 64-bit, but not very clear minded. Here is a good article I found about it. http://www.techsupportalert.com/content/32-bit-and-64-bit-explained.htm   Understand there are 3 things involved: CPU, OS and application. To work on 64-bit, first thing first is: you need a 64-bit CPU. 64-bit CPU usually provide emulation for 32-bit system. Though some 32-bit application still cannot run on 64-bit OS, because they might contain 16-bit code. 32-bit system won't have com...

       2015-12-08 03:04:01

  Facebook open sources its C++ library named Folly

Recently, Facebook open sourced its low level C++ function library for its internal use named Folly. Folly is an open sourced C++11 component library, it provides functions similar to what boost and std libraries provide, including string, vector and memory allocation, bit operation etc, to fulfill large scale high performance requirements.Currently Folly is tested with gcc4.6 on some 64 bit systems such as Fedora 17, Ubuntu 12.04 and Debian wheezy, it may also be OK on other 64 bit platforms wi...

   Facebook,Folly,C++,open source     2012-06-05 08:31:12

  Install both 32 bit and 64 bit WAMP server

WAMP server is a platform tool for serving PHP applications on Windows. It includes a combination of Apache, MySQL and PHP service which can help developers test or run PHP applications with minimal setup. Sometimes one would first have a 32 bit version of WAMP installed and a few applications have been configured. But later s/he would mistakenly installed a 64 bit version of WAMP and somehow the 32 bit version configuration is overwritten. This causes a problem where the old applications config...

   PHP,WAMP,64 BIT,32 BIT,MULTIPLE VERSION     2017-03-18 01:14:21

  Want to install 64 bit OS on VirtualBox?

By default, VirtualBox only allows to install 32 bit OS on it. But sometimes, 64 bit OS is wanted for specific uses such as running platform specific tests. To allow installing 64 bit OS on VirtualBox. Below information is needed. Here is the official documentation about 64 bit OS: VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met: You need a 64-bit processor with hardware virtualization support (see the ...

   VirtualBox,64 bit,hardware virtualization,Ubuntu     2014-11-08 03:52:07

  Windows 8 price is unveiled

Although it's still half month away from releases of Windows 8, Microsoft releases price of all versions of Windows 8 on Windowsteam blog. From now on, users can pre-order this product on Amazon, Bestbuy, Staples and Office Depot. The prices for different version : Windows 8 Professional Upgrade : $69.99 Windows 8 Pro Pack-Product Key Card : $69.99 Windows 8 64 bit(Full Version) -- OEM : $99.99 Windows 8 32 bit (Full Version) -- OEM : $99.99 Windows 8 Professional 32 bit (Full Version) -- OEM ...

   Windows 8, Price     2012-10-12 20:03:55

  + operation on JavaScript objects

In JavaScript, there are two types of values: primitive and object. Primitives consist undefined, null, boolean, number and string. Other values such as array and function are objects. When applying + operation on different type of values, there would be three kinds of type conversion. Primitive conversion Number conversion String conversion There three type conversions have corresponding abstract operations in JavaScript: ToPrimitive(), ToNumber(), ToString(). For number additi...

   JAVASCRIPT,PROGRAMMING     2018-10-12 22:19:12

  Why you should be careful about optimizations

In one of my current javascript projects, I have to deal with 3D voxel coordinates. And, sometimes, I have floating points coordinates which must be converted to integers in order to convert them into proper array index. Javascript is a wonderful language, really. However, implementations are sometimes weird, and the way to do something can sometimes have very huge impacts on the performances. Worse, sometimes the classical way is more expensive than the tricky one. So, some peo...

   JavaScript,Bitwise,Floor,Trick,Optimization     2012-05-02 11:29:20

  Understand more about Go basics with one interview question

First, let's take a look at below Go interview question: package main const s = "Go101.org" // len(s) == 9 // 1 << 9 == 512 // 512 / 128 == 4 var a byte = 1 << len(s) / 128 var b byte = 1 << len(s[:]) / 128 func main() { println(a, b) } What would be the output in your mind? The output would be 4 0. Surprising? Before getting to the output values, some concepts in Go need to be introduced and explained in more detail. len()  len() is a built-in function in Go to get t...

   GOLANG,CONSTANT,SHIFT OPERATION,LEN()     2020-10-10 02:52:19

  Why 0.1+0.2 != 0.3

In programming languages such as JavaScript, c/c++, Java and Matlab, you will find that you will get unexpected result when doing float point calculation. For example, when calculating 0.1 + 0.1, you will not get 0.3: > 0.1 + 0.2 == 0.3 false > 0.1 + 0.2 0.30000000000000004 Don't be surprised of this result, this is the end result of IEEE 754 standard, float point number cannot be accurately represented according to IEEE 754 because: No enough memory is allocated for representing the num...

   float point,comparison,JavaScript     2014-11-19 05:32:46

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