Add endian parameter to the get/set functions in ByteData.

sdk/lib/typeddata/typeddata.dart

Index: sdk/lib/typeddata/typeddata.dart
===================================================================
--- sdk/lib/typeddata/typeddata.dart	(revision 21661)
+++ sdk/lib/typeddata/typeddata.dart	(working copy)
@@ -49,6 +49,23 @@
 
 
 /**
+ * Describes endianness to be used when accessing or updating a
+ * sequence of bytes.
+ */
+class Endianness {
+  const Endianness._(this._littleEndian);
+
+  static const Endianness BIG_ENDIAN = const Endianness._(false);
+  static const Endianness LITTLE_ENDIAN = const Endianness._(true);

[sra1, 2013/04/19 18:31:33]

These names are rather verbose and you can't write LITTLE_ENDIAN without the
class name Endianness:

bdata.getUint16(i, Endianness.LITTLE_ENDIAN)

How about removing some of the internal redundancy in the name to allow the user
to write:

bdata.getUint16(i, Endian.LITTLE)

+  static final Endianness HOST_ENDIAN =
+    (new ByteData.view(new Uint16List.fromList([1]).buffer)).getInt8(0) == 1 ?
+    LITTLE_ENDIAN : BIG_ENDIAN;
+
+  final bool _littleEndian;
+}
+
+
+/**
  * A fixed-length, random-access sequence of bytes that also provides random
  * and unaligned access to the fixed-width integers and floating point
  * numbers represented by those bytes.
@@ -141,7 +158,7 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 2` is greater than the length of this object.
    */
-  int getInt16(int byteOffset);
+  int getInt16(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);

[sra1, 2013/04/19 18:31:33]

My recommendation at
https://code.google.com/p/dart/issues/detail?id=8220#c10
was to use a bool parameter 'littleEndian' that defaults to false for big
endian.

This recommendation allows the Dart code to compile directly to JavaScript
without needing to coax the compiler into achieving the required optimizations.

dart2js does not yet do all the optimizations necessary to reduce a Dart call
site data.getInt16(i) to the equivalent JavaScript code (i.e. data.getInt16(i)).

 
   /**
    * Sets the two bytes starting at the specified [byteOffset] in this
@@ -152,7 +169,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 2` is greater than the length of this object.
    */
-  void setInt16(int byteOffset, int value);
+  void setInt16(int byteOffset,
+                int value,
+                [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the positive integer represented by the two bytes starting
@@ -163,7 +182,7 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 2` is greater than the length of this object.
    */
-  int getUint16(int byteOffset);
+  int getUint16(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the two bytes starting at the specified [byteOffset] in this object
@@ -174,7 +193,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 2` is greater than the length of this object.
    */
-  void setUint16(int byteOffset, int value);
+  void setUint16(int byteOffset,
+                 int value,
+                 [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the (possibly negative) integer represented by the four bytes at
@@ -186,7 +207,7 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 4` is greater than the length of this object.
    */
-  int getInt32(int byteOffset);
+  int getInt32(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the four bytes starting at the specified [byteOffset] in this
@@ -197,7 +218,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 4` is greater than the length of this object.
    */
-  void setInt32(int byteOffset, int value);
+  void setInt32(int byteOffset,
+                int value,
+                [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the positive integer represented by the four bytes starting
@@ -206,7 +229,7 @@
    * The return value will be between 0 and  2<sup>32</sup> - 1, inclusive.
    *
    */
-  int getUint32(int byteOffset);
+  int getUint32(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the four bytes starting at the specified [byteOffset] in this object
@@ -217,7 +240,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 4` is greater than the length of this object.
    */
-  void setUint32(int byteOffset, int value);
+  void setUint32(int byteOffset,
+                 int value,
+                 [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the (possibly negative) integer represented by the eight bytes at
@@ -229,7 +254,7 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 8` is greater than the length of this object.
    */
-  int getInt64(int byteOffset);
+  int getInt64(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the eight bytes starting at the specified [byteOffset] in this
@@ -240,7 +265,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 8` is greater than the length of this object.
    */
-  void setInt64(int byteOffset, int value);
+  void setInt64(int byteOffset,
+                int value,
+                [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the positive integer represented by the eight bytes starting
@@ -251,7 +278,7 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 8` is greater than the length of this object.
    */
-  int getUint64(int byteOffset);
+  int getUint64(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the eight bytes starting at the specified [byteOffset] in this object
@@ -262,7 +289,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 8` is greater than the length of this object.
    */
-  void setUint64(int byteOffset, int value);
+  void setUint64(int byteOffset,
+                 int value,
+                 [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the floating point number represented by the four bytes at
@@ -272,7 +301,8 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 4` is greater than the length of this object.
    */
-  double getFloat32(int byteOffset);
+  double getFloat32(int byteOffset,
+                    [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the four bytes starting at the specified [byteOffset] in this
@@ -291,7 +321,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 4` is greater than the length of this object.
    */
-  void setFloat32(int byteOffset, double value);
+  void setFloat32(int byteOffset,
+                  double value,
+                  [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Returns the floating point number represented by the eight bytes at
@@ -301,7 +333,8 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 8` is greater than the length of this object.
    */
-  double getFloat64(int byteOffset);
+  double getFloat64(int byteOffset,
+                    [Endianness endian = Endianness.BIG_ENDIAN]);
 
   /**
    * Sets the eight bytes starting at the specified [byteOffset] in this
@@ -311,7 +344,9 @@
    * Throws [RangeError] if [byteOffset] is negative, or
    * `byteOffset + 8` is greater than the length of this object.
    */
-  void setFloat64(int byteOffset, double value);
+  void setFloat64(int byteOffset,
+                  double value,
+                  [Endianness endian = Endianness.BIG_ENDIAN]);
 }