a very simple bitfield implementation using buffers
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a very simple bitfield, compliant with the Bittorrent spec

npm install bitfield


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


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.


Bitfield#buffer: The contents of the bitfield.

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