1 files changed, 95 insertions, 0 deletions
diff --git a/node_modules/sparse-bitfield/index.js b/node_modules/sparse-bitfield/index.js
new file mode 100644
index 0000000..ff458c9
--- /dev/null
+++ b/node_modules/sparse-bitfield/index.js
@@ -0,0 +1,95 @@
+var pager = require('memory-pager')
+
+module.exports = Bitfield
+
+function Bitfield (opts) {
+  if (!(this instanceof Bitfield)) return new Bitfield(opts)
+  if (!opts) opts = {}
+  if (Buffer.isBuffer(opts)) opts = {buffer: opts}
+
+  this.pageOffset = opts.pageOffset || 0
+  this.pageSize = opts.pageSize || 1024
+  this.pages = opts.pages || pager(this.pageSize)
+
+  this.byteLength = this.pages.length * this.pageSize
+  this.length = 8 * this.byteLength
+
+  if (!powerOfTwo(this.pageSize)) throw new Error('The page size should be a power of two')
+
+  this._trackUpdates = !!opts.trackUpdates
+  this._pageMask = this.pageSize - 1
+
+  if (opts.buffer) {
+    for (var i = 0; i < opts.buffer.length; i += this.pageSize) {
+      this.pages.set(i / this.pageSize, opts.buffer.slice(i, i + this.pageSize))
+    }
+    this.byteLength = opts.buffer.length
+    this.length = 8 * this.byteLength
+  }
+}
+
+Bitfield.prototype.get = function (i) {
+  var o = i & 7
+  var j = (i - o) / 8
+
+  return !!(this.getByte(j) & (128 >> o))
+}
+
+Bitfield.prototype.getByte = function (i) {
+  var o = i & this._pageMask
+  var j = (i - o) / this.pageSize
+  var page = this.pages.get(j, true)
+
+  return page ? page.buffer[o + this.pageOffset] : 0
+}
+
+Bitfield.prototype.set = function (i, v) {
+  var o = i & 7
+  var j = (i - o) / 8
+  var b = this.getByte(j)
+
+  return this.setByte(j, v ? b | (128 >> o) : b & (255 ^ (128 >> o)))
+}
+
+Bitfield.prototype.toBuffer = function () {
+  var all = alloc(this.pages.length * this.pageSize)
+
+  for (var i = 0; i < this.pages.length; i++) {
+    var next = this.pages.get(i, true)
+    var allOffset = i * this.pageSize
+    if (next) next.buffer.copy(all, allOffset, this.pageOffset, this.pageOffset + this.pageSize)
+  }
+
+  return all
+}
+
+Bitfield.prototype.setByte = function (i, b) {
+  var o = i & this._pageMask
+  var j = (i - o) / this.pageSize
+  var page = this.pages.get(j, false)
+
+  o += this.pageOffset
+
+  if (page.buffer[o] === b) return false
+  page.buffer[o] = b
+
+  if (i >= this.byteLength) {
+    this.byteLength = i + 1
+    this.length = this.byteLength * 8
+  }
+
+  if (this._trackUpdates) this.pages.updated(page)
+
+  return true
+}
+
+function alloc (n) {
+  if (Buffer.alloc) return Buffer.alloc(n)
+  var b = new Buffer(n)
+  b.fill(0)
+  return b
+}
+
+function powerOfTwo (x) {
+  return !(x & (x - 1))
+}