BitArray alternative for the .NET Micro Framework

Posted on

Problem :

Is there a BitArray alternative for the .NET Micro Framework?
I was thinking about simply using a bool[], but how can you convert it back
into a byte[] ?

In the full framework, considering “bits” is a BitArray, the following works:

byte[] data = new byte[dimensions / 8];
bits.CopyTo(data, 0);

But I cannot seem to find the BitArray class in the micro framework

Solution :

It’s not terribly difficult to duplicate the functionality of BitArray. First, if you need fewer than 65 bits, then you can do it with a long or smaller.

To set an individual bit:

void Set(ref long ba, int bit)
    ba |= 1L << bit;

To clear a bit:

void Clear(ref long ba, int bit)
    long mask = 1L << bit;
    mask = ~mask;
    ba &= mask;

To see if a bit is set:

bool IsSet(long ba, int bit)
    long mask = 1L << bit;
    return (ba & mask) != 0;

If you have more than 64 bits, then you’ll need to create an array (byte[], probably), and do the division to determine which byte/bit you want to modify. The methods above will work, provided you change the long to byte.

For example, if you have:

byte[] myBytes = new byte[128];

You have 1024 bits.

To set a bit:

void Set (int bit)
    int byte = bit/8;
    int bitIndex = bit%8;
    myBytes[byte] |= (byte)(1 << bitIndex);

The other methods use the same math to get the byte and bit index, and setting, clearing, and testing a bit is the same as with the long example above.

You can find a BitArray Implementation in the 802.15.4 Stack. Just search the Porting Kit for BitArray.cs

I uploaded an array for .net microframework:

Hope this helps.

Leave a Reply

Your email address will not be published. Required fields are marked *