Fixes bug in typed data read/write for floats and doubles.

runtime/lib/typed_data.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // patch classes for Int8List ..... Float64List and ByteData implementations.
 
 import "dart:_internal";
 import 'dart:math' show Random;
 
 patch class Int8List {
@@ skipping 3428 matching lines @@
     }
     _typedData._setUint64(_offset + byteOffset,
         identical(endian, Endianness.HOST_ENDIAN) ? value : _byteSwap64(value));
   }
 
   double getFloat32(int byteOffset,
                     [Endianness endian = Endianness.BIG_ENDIAN]) {
     if (byteOffset < 0 || byteOffset + 3 >= length) {
       throw _newRangeError(byteOffset + 3, length);
     }
-    var result = _typedData._getFloat32(_offset + byteOffset);
     if (identical(endian, Endianness.HOST_ENDIAN)) {
-      return result;
+      return _typedData._getFloat32(_offset + byteOffset);
     }
-    return _byteSwapFloat32(result);
+    _convU32[0] = _byteSwap32(_typedData._getUint32(_offset + byteOffset));
+    return _convF32[0];
   }
   void setFloat32(int byteOffset,
                   double value,
                   [Endianness endian = Endianness.BIG_ENDIAN]) {
     if (byteOffset < 0 || byteOffset + 3 >= length) {
       throw _newRangeError(byteOffset + 3, length);
     }
-    _typedData._setFloat32(_offset + byteOffset,
-        identical(endian, Endianness.HOST_ENDIAN) ? value
-                                                  : _byteSwapFloat32(value));
+    if (identical(endian, Endianness.HOST_ENDIAN)) {
+      _typedData._setFloat32(_offset + byteOffset, value);
+      return;
+    }
+    _convF32[0] = value;
+    _typedData._setUint32(_offset + byteOffset, _byteSwap32(_convU32[0]));
   }
 
   double getFloat64(int byteOffset,
                     [Endianness endian = Endianness.BIG_ENDIAN]) {
     if (byteOffset < 0 || byteOffset + 7 >= length) {
       throw _newRangeError(byteOffset + 7, length);
     }
-    var result = _typedData._getFloat64(_offset + byteOffset);
     if (identical(endian, Endianness.HOST_ENDIAN)) {
-      return result;
+      return _typedData._getFloat64(_offset + byteOffset);
     }
-    return _byteSwapFloat64(result);
+    _convU64[0] = _byteSwap64(_typedData._getUint64(_offset + byteOffset));
+    return _convF64[0];
   }
   void setFloat64(int byteOffset,
                   double value,
                   [Endianness endian = Endianness.BIG_ENDIAN]) {
     if (byteOffset < 0 || byteOffset + 7 >= length) {
       throw _newRangeError(byteOffset + 7, length);
     }
-    _typedData._setFloat64(_offset + byteOffset,
-        identical(endian, Endianness.HOST_ENDIAN) ? value
-                                                  : _byteSwapFloat64(value));
+    if (identical(endian, Endianness.HOST_ENDIAN)) {
+      _typedData._setFloat64(_offset + byteOffset, value);
+      return;
+    }
+    _convF64[0] = value;
+    _typedData._setUint64(_offset + byteOffset, _byteSwap64(_convU64[0]));
   }
 
   Float32x4 getFloat32x4(int byteOffset,
                          [Endianness endian = Endianness.BIG_ENDIAN]) {
     if (byteOffset < 0 || byteOffset + 3 >= length) {
       throw _newRangeError(byteOffset + 3, length);
     }
     // TODO(johnmccutchan) : Need to resolve this for endianity.
     return _typedData._getFloat32x4(_offset + byteOffset);
   }
@@ skipping 22 matching lines @@
   value = ((value & 0xFF00FF00) >> 8)  | ((value & 0x00FF00FF) << 8);
   value = ((value & 0xFFFF0000) >> 16) | ((value & 0x0000FFFF) << 16);
   return value;
 }
 
 int _byteSwap64(int value) {
   return (_byteSwap32(value) << 32) | _byteSwap32(value >> 32);
 }
 
 final _convU32 = new Uint32List(2);
+final _convU64 = new Uint64List.view(_convU32.buffer);
 final _convF32 = new Float32List.view(_convU32.buffer);
 final _convF64 = new Float64List.view(_convU32.buffer);
 
-double _byteSwapFloat32(double value) {
-  _convF32[0] = value;
-  _convU32[0] = _byteSwap32(_convU32[0]);
-  return _convF32[0];
-}
-
-double _byteSwapFloat64(double value) {
-  _convF64[0] = value;
-  var lo = _convU32[0];
-  _convU32[0] = _byteSwap32(_convU32[1]);
-  _convU32[1] = _byteSwap32(lo);
-  return _convF64[0];
-}
-
 // Top level utility methods.
 int _toInt(int value, int mask) {
   value &= mask;
   if (value > (mask >> 1)) value -= mask + 1;
   return value;
 }
 
 
 int _toInt8(int value) {
   return _toInt(value, 0xFF);
@@ skipping 72 matching lines @@
     return value;
   }
   return object;
 }
 
 
 _newRangeError(int index, int length) {
   String message = "$index must be in the range [0..$length)";
   return new RangeError(message);
 }