node package manager

bitfield

bitfield

a very simple bitfield, compliant with the Bittorrent spec

npm install bitfield

Example

var Bitfield = require("bitfield");
 
var field = new Bitfield(256); //create a bitfield with 256 bits
 
field.set(128); //set the 128th bit
field.set(128, true); //same as above
 
field.get(128); //true
field.get(200); //false (all values are initialised to `false`)
field.get(1e3); //false (out-of-bounds is also false)
 
field.set(128, false); //set the 128th bit to 0 again
 
field.buffer; //the buffer used by bitfield

Methods

Bitfield(data): data can be either a node.js buffer, WebGL Int8Array or numeric array, or a number representing the maximum number of supported bytes.

Bitfield#get(index): Returns a boolean indicating whether the bit is set.

Bitfield#set(index[, value]): value defaults to true. Sets the bit to 1 for a value of true or 0 for false.

Auto-grow mode

Bitfield(data, { grow: size }): If you set an index that is out-of-bounds, the Bitfield will automatically grow so that the bitfield is big enough to contain the given index, up to the given size (in bit). If you want the Bitfield to grow indefinitely, pass Infinity as the size.

Properties

Bitfield#buffer: The contents of the bitfield.

Bitfield#grow: The passed growth option (defaults to 0).

License

MIT