Have you ever had to use bit shifting in real projects?

Question

Have you ever had to use bit shifting in real programming projects? Most (if not all) high level languages have shift operators in them, but when would you actually need to

Answer 1

I've used them on games for packing a bunch of flags into a single byte / char for saving out to a data card. Things like storing the status of unlockables etc. Not so much of a requirement nowadays, but can save work.

Answer 2

Yes, I have. As you might suspect it's most likely to be found in low level programming, for example developing devices' drivers. But, I worked on a C# project where I had to develop a web service that received data from medical devices. All the binary data that device stored was encoded into SOAP packets, but the binary data was compressed and encoded. So to uncompress it, you would have to do lots and lots of bit manipulations. And furthermore you would have to do lots of bit shifting to parse out any useful information, for example device serial number is a lower half of the second byte or something like that. Also I've seen some people in .NET (C#) world make a use of Bit masking and Flag Attribute, I personally never had an urge to do it.

Answer 3

I once (many, many years ago) wrote an output routine for a project which created Excel Spreadsheets using the Excel Oper structure. This was a binary file formant which required a large amount of bit twiddling. The following link gives a flavour of the Oper structure Safari Books.

Answer 4

Yes, used them in MPEG2-2 Transport stream parser. It was easier and was better readable.

Answer 5

Yes, still it's needed.

Here in my job for example we develop softwares for comunication with PLC through the serial port COMx. It's necessary to handle bits within a byte, we use shift left / right, and logic operators OR,XOR,AND in day by day.

For example, let's suppose that we need turn on the bit 3 (right to left) of a byte:

It's much more efficient to do:

Byte B;

B := B XOR 4;

Instead of:

Byte B = 0;
String s;  // 0 based index

s = ConvertToBinary (B);
s[5] = "1";
B := ConvertToDecimal (s);

Regards.

Answer 6

Every bitblt-er i ever wrote couldn't have been completed w/o ability to slide bits left and right.