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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

  + 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

  Why are column oriented databases so much faster than row oriented databases?

I have been playing around with Hybrid Word Aligned Bitmaps for a few weeks now, and they turn out to be a rather remarkable data structure.  I believe that they are utilized extensively in modern column oriented databases such as Vertica and MonetDB. Essentially HWABs are a data structure that allows you to represent a sparse bitmap (series of 0's and 1's) really efficiently in memory.  The key trick here is the use of run length encoding to compress the bitmap into fe...

   Database,Column oriented,Speed analysis,Vertica     2012-01-29 04:27:05

  ARM adopts 64-bit architecture

ARM has disclosed technical details about its new v8 architecture - the first to include a 64-bit instruction set - at ARM TechCon 2011 in Santa Clara, California.The next-gen architecture will expand the reach of ARM processors in the consumer and enterprise markets where extended virtual addressing and 64-bit data processing are required.According to ARM CTO Mike Muller, ARMv8 architecture consists of two main execution states: AArch64 and AArch32. 

The AArch64 execution state int...

   ARM,Processor,64 bit,Architecture,v8,Nvidia     2011-10-28 10:31:52

  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 Control panel mail icon

The exact location depends on your version of Windows and your layout settings of Control Panel. If your Control Panel is in the classic layout, you should see the Mail applet directly in the list of icons. For a 64-bit version of Windows Vista, the icon would be listed in the “View 32-bit Control Panel Items” section. If your Control Panel is in category view you can find the Mail applet in; Windows XP: User Accounts Windows Vista: User Accounts Windows Vista 64-bit: Additional O...

   Windows,Control panel,Mail icon,Outlook     2011-04-26 06:15:05

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