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author | 2020-11-16 00:10:28 +0100 | |
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committer | 2020-11-16 00:10:28 +0100 | |
commit | e06ec920f7a5d784e674c4c4b4e6d1da3dc7391d (patch) | |
tree | 55713f725f77b44ebfec86e4eec3ce33e71458ca /node_modules/sparse-bitfield/index.js | |
download | website_creator-e06ec920f7a5d784e674c4c4b4e6d1da3dc7391d.tar.gz website_creator-e06ec920f7a5d784e674c4c4b4e6d1da3dc7391d.tar.bz2 website_creator-e06ec920f7a5d784e674c4c4b4e6d1da3dc7391d.zip |
api, login, auth
Diffstat (limited to 'node_modules/sparse-bitfield/index.js')
-rw-r--r-- | node_modules/sparse-bitfield/index.js | 95 |
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)) +} |