auroranockert · May 19, 2012 13:48
diff --git a/file.js b/file.js
 <!DOCTYPE html>

 <head>
 	<meta charset='utf-8'>
 	
 	<title>file.js</title>
 	
 	<script>
 	
 	function file(url, callback) {
 		this.url = url, this.pagesize = 65536
 		
 		var request = new XMLHttpRequest()
 		
 		request.open("HEAD", this.url, true)
 		
 		var self = this
 		
 		request.addEventListener("load", function () {
 			self.length = parseInt(request.getResponseHeader("Content-length"), 10)
 			
 			self.pages = Math.ceil(self.length / self.pagesize), self.open = true
 			
 			self.status = new Array(self.pages), self.data = new ArrayBuffer(self.length)
 			
 			callback(self)
 		}, false)
 		
 		request.addEventListener("error", function () {
 			self.open = false
 			
 			callback(self)
 		}, false)
 		
 		request.send()
 	}
 	
 	file.prototype.prefetch = function (offset, length) {
 		this.read(offset, length)		
 	}
 	
 	file.prototype.readPages = function (start, pages, positive, negative) {
 		if (pages < 1) {
 			positive(); return
 		}
 		
 		var request = new XMLHttpRequest()
 		
 		request.open("GET", this.url, true)
 		
 		request.responseType = "arraybuffer"
 		request.setRequestHeader("Range", "bytes=" + (start * this.pagesize) + "-" + ((start + pages) * this.pagesize - 1))
 		
 		var self = this
 		
 		request.addEventListener("load", function () {
 			var sourceView = new Uint8Array(request.response)
 			var destinationView = new Uint8Array(self.data, start * self.pagesize, pages * self.pagesize)
 			
 			destinationView.set(sourceView)
 			
 			for (var i = 0; i < pages; i++) {
 				self.status[start + i] = true
 			}
 			
 			positive()
 		}, true)
 		
 		for (var i = 0; i < pages; i++) {
 			this.status[start + i] = request
 		}
 		
 		request.addEventListener("error", negative, false)
 		
 		request.send()
 	}
 	
 	file.prototype.read = function (offset, length, callback) {
 		var self = this
 		
 		var startpage = Math.floor(offset / this.pagesize), pages = Math.ceil(length / this.pagesize)
 		
 		var connections = 1, finished = 0, failed = 0
 		
 		function transferComplete() {
 			finished += 1
 			
 			if (callback && (finished == connections)) {
 				if (failed == 0) {
 					callback(self, new DataView(self.data, offset, length))
 				} else {
 					callback(self)
 				}
 			}
 		}
 		
 		function transferFailed () {
 			finished += 1; failed += 1
 			
 			if (callback && (finished == connections)) {
 				callback(self)
 			}
 		}
 		
 		var start = pages, inRange = false
 		
 		for (var i = 0; i < pages; i++) {
 			var value = this.status[startpage + i]
 			
 			if (value) {
 				if (inRange) {
 					connections += 1
 				
 					this.readPages(startpage + start, i - start, transferComplete, transferFailed)
 					
 					inRange = false
 				}
 				
 				if (value !== true) {
 					connections += 1
 					
 					value.addEventListener("load", function () { transferComplete() }, false) /* Stupid addEventListener… */
 					value.addEventListener("error", function () { transferFailed() }, false)
 				}
 			} else {
 				if (!inRange) {
 					inRange = true, start = i
 				}
 			}
 		}
 		
 		this.readPages(startpage + start, pages - start, transferComplete, transferFailed)
 	}
 	
 	f = new file("[email protected]", function (file) {
 		file.prefetch(8 * file.pagesize, file.pagesize)
 		file.prefetch(0, 16 * file.pagesize)
 		
 		file.read(0, 16 * file.pagesize, function (file, data) {
 			console.log("Here!")
 		})
 	})
 	
 	</script>
 </head>
	<!DOCTYPE html>

	<head>
	<meta charset='utf-8'>

	<title>file.js</title>

	<script>

	function file(url, callback) {
	this.url = url, this.pagesize = 65536

	var request = new XMLHttpRequest()

	request.open("HEAD", this.url, true)

	var self = this

	request.addEventListener("load", function () {
	self.length = parseInt(request.getResponseHeader("Content-length"), 10)

	self.pages = Math.ceil(self.length / self.pagesize), self.open = true

	self.status = new Array(self.pages), self.data = new ArrayBuffer(self.length)

	callback(self)
	}, false)

	request.addEventListener("error", function () {
	self.open = false

	callback(self)
	}, false)

	request.send()
	}

	file.prototype.prefetch = function (offset, length) {
	this.read(offset, length)
	}

	file.prototype.readPages = function (start, pages, positive, negative) {
	if (pages < 1) {
	positive(); return
	}

	var request = new XMLHttpRequest()

	request.open("GET", this.url, true)

	request.responseType = "arraybuffer"
	request.setRequestHeader("Range", "bytes=" + (start * this.pagesize) + "-" + ((start + pages) * this.pagesize - 1))

	var self = this

	request.addEventListener("load", function () {
	var sourceView = new Uint8Array(request.response)
	var destinationView = new Uint8Array(self.data, start * self.pagesize, pages * self.pagesize)

	destinationView.set(sourceView)

	for (var i = 0; i < pages; i++) {
	self.status[start + i] = true
	}

	positive()
	}, true)

	for (var i = 0; i < pages; i++) {
	this.status[start + i] = request
	}

	request.addEventListener("error", negative, false)

	request.send()
	}

	file.prototype.read = function (offset, length, callback) {
	var self = this

	var startpage = Math.floor(offset / this.pagesize), pages = Math.ceil(length / this.pagesize)

	var connections = 1, finished = 0, failed = 0

	function transferComplete() {
	finished += 1

	if (callback && (finished == connections)) {
	if (failed == 0) {
	callback(self, new DataView(self.data, offset, length))
	} else {
	callback(self)
	}
	}
	}

	function transferFailed () {
	finished += 1; failed += 1

	if (callback && (finished == connections)) {
	callback(self)
	}
	}

	var start = pages, inRange = false

	for (var i = 0; i < pages; i++) {
	var value = this.status[startpage + i]

	if (value) {
	if (inRange) {
	connections += 1

	this.readPages(startpage + start, i - start, transferComplete, transferFailed)

	inRange = false
	}

	if (value !== true) {
	connections += 1

	value.addEventListener("load", function () { transferComplete() }, false) /* Stupid addEventListener… */
	value.addEventListener("error", function () { transferFailed() }, false)
	}
	} else {
	if (!inRange) {
	inRange = true, start = i
	}
	}
	}

	this.readPages(startpage + start, pages - start, transferComplete, transferFailed)
	}

	f = new file("[email protected]", function (file) {
	file.prefetch(8 * file.pagesize, file.pagesize)
	file.prefetch(0, 16 * file.pagesize)

	file.read(0, 16 * file.pagesize, function (file, data) {
	console.log("Here!")
	})
	})

	</script>
	</head>