mojo/public/js/buffer.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 define("mojo/public/js/buffer", function() {
   6
   7   var kHostIsLittleEndian = (function () {
   8     var endianArrayBuffer = new ArrayBuffer(2);
   9     var endianUint8Array = new Uint8Array(endianArrayBuffer);
  10     var endianUint16Array = new Uint16Array(endianArrayBuffer);
  11     endianUint16Array[0] = 1;
  12     return endianUint8Array[0] == 1;
  13   })();
  14
  15   var kHighWordMultiplier = 0x100000000;
  16
  17   function Buffer(sizeOrArrayBuffer) {
  18     if (sizeOrArrayBuffer instanceof ArrayBuffer)
  19       this.arrayBuffer = sizeOrArrayBuffer;
  20     else
  21       this.arrayBuffer = new ArrayBuffer(sizeOrArrayBuffer);
  22
  23     this.dataView = new DataView(this.arrayBuffer);
  24     this.next = 0;
  25   }
  26
  27   Object.defineProperty(Buffer.prototype, "byteLength", {
  28     get: function() { return this.arrayBuffer.byteLength; }
  29   });
  30
  31   Buffer.prototype.alloc = function(size) {
  32     var pointer = this.next;
  33     this.next += size;
  34     if (this.next > this.byteLength) {
  35       var newSize = (1.5 * (this.byteLength + size)) | 0;
  36       this.grow(newSize);
  37     }
  38     return pointer;
  39   };
  40
  41   function copyArrayBuffer(dstArrayBuffer, srcArrayBuffer) {
  42     (new Uint8Array(dstArrayBuffer)).set(new Uint8Array(srcArrayBuffer));
  43   }
  44
  45   Buffer.prototype.grow = function(size) {
  46     var newArrayBuffer = new ArrayBuffer(size);
  47     copyArrayBuffer(newArrayBuffer, this.arrayBuffer);
  48     this.arrayBuffer = newArrayBuffer;
  49     this.dataView = new DataView(this.arrayBuffer);
  50   };
  51
  52   Buffer.prototype.trim = function() {
  53     this.arrayBuffer = this.arrayBuffer.slice(0, this.next);
  54     this.dataView = new DataView(this.arrayBuffer);
  55   };
  56
  57   Buffer.prototype.getUint8 = function(offset) {
  58     return this.dataView.getUint8(offset);
  59   }
  60   Buffer.prototype.getUint16 = function(offset) {
  61     return this.dataView.getUint16(offset, kHostIsLittleEndian);
  62   }
  63   Buffer.prototype.getUint32 = function(offset) {
  64     return this.dataView.getUint32(offset, kHostIsLittleEndian);
  65   }
  66   Buffer.prototype.getUint64 = function(offset) {
  67     var lo, hi;
  68     if (kHostIsLittleEndian) {
  69       lo = this.dataView.getUint32(offset, kHostIsLittleEndian);
  70       hi = this.dataView.getUint32(offset + 4, kHostIsLittleEndian);
  71     } else {
  72       hi = this.dataView.getUint32(offset, kHostIsLittleEndian);
  73       lo = this.dataView.getUint32(offset + 4, kHostIsLittleEndian);
  74     }
  75     return lo + hi * kHighWordMultiplier;
  76   }
  77
  78   Buffer.prototype.getInt8 = function(offset) {
  79     return this.dataView.getInt8(offset);
  80   }
  81   Buffer.prototype.getInt16 = function(offset) {
  82     return this.dataView.getInt16(offset, kHostIsLittleEndian);
  83   }
  84   Buffer.prototype.getInt32 = function(offset) {
  85     return this.dataView.getInt32(offset, kHostIsLittleEndian);
  86   }
  87   Buffer.prototype.getInt64 = function(offset) {
  88     var lo, hi;
  89     if (kHostIsLittleEndian) {
  90       lo = this.dataView.getUint32(offset, kHostIsLittleEndian);
  91       hi = this.dataView.getInt32(offset + 4, kHostIsLittleEndian);
  92     } else {
  93       hi = this.dataView.getInt32(offset, kHostIsLittleEndian);
  94       lo = this.dataView.getUint32(offset + 4, kHostIsLittleEndian);
  95     }
  96     return lo + hi * kHighWordMultiplier;
  97   }
  98
  99   Buffer.prototype.getFloat32 = function(offset) {
 100     return this.dataView.getFloat32(offset, kHostIsLittleEndian);
 101   }
 102   Buffer.prototype.getFloat64 = function(offset) {
 103     return this.dataView.getFloat64(offset, kHostIsLittleEndian);
 104   }
 105
 106   Buffer.prototype.setUint8 = function(offset, value) {
 107     this.dataView.setUint8(offset, value);
 108   }
 109   Buffer.prototype.setUint16 = function(offset, value) {
 110     this.dataView.setUint16(offset, value, kHostIsLittleEndian);
 111   }
 112   Buffer.prototype.setUint32 = function(offset, value) {
 113     this.dataView.setUint32(offset, value, kHostIsLittleEndian);
 114   }
 115   Buffer.prototype.setUint64 = function(offset, value) {
 116     var hi = (value / kHighWordMultiplier) | 0;
 117     if (kHostIsLittleEndian) {
 118       this.dataView.setInt32(offset, value, kHostIsLittleEndian);
 119       this.dataView.setInt32(offset + 4, hi, kHostIsLittleEndian);
 120     } else {
 121       this.dataView.setInt32(offset, hi, kHostIsLittleEndian);
 122       this.dataView.setInt32(offset + 4, value, kHostIsLittleEndian);
 123     }
 124   }
 125
 126   Buffer.prototype.setInt8 = function(offset, value) {
 127     this.dataView.setInt8(offset, value);
 128   }
 129   Buffer.prototype.setInt16 = function(offset, value) {
 130     this.dataView.setInt16(offset, value, kHostIsLittleEndian);
 131   }
 132   Buffer.prototype.setInt32 = function(offset, value) {
 133     this.dataView.setInt32(offset, value, kHostIsLittleEndian);
 134   }
 135   Buffer.prototype.setInt64 = function(offset, value) {
 136     var hi = Math.floor(value / kHighWordMultiplier);
 137     if (kHostIsLittleEndian) {
 138       this.dataView.setInt32(offset, value, kHostIsLittleEndian);
 139       this.dataView.setInt32(offset + 4, hi, kHostIsLittleEndian);
 140     } else {
 141       this.dataView.setInt32(offset, hi, kHostIsLittleEndian);
 142       this.dataView.setInt32(offset + 4, value, kHostIsLittleEndian);
 143     }
 144   }
 145
 146   Buffer.prototype.setFloat32 = function(offset, value) {
 147     this.dataView.setFloat32(offset, value, kHostIsLittleEndian);
 148   }
 149   Buffer.prototype.setFloat64 = function(offset, value) {
 150     this.dataView.setFloat64(offset, value, kHostIsLittleEndian);
 151   }
 152
 153   var exports = {};
 154   exports.Buffer = Buffer;
 155   return exports;
 156 });