v8 typed arrays: add DataView type

src/utils.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 228 matching lines @@
 }
 
 
 inline int StrLength(const char* string) {
   size_t length = strlen(string);
   ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
   return static_cast<int>(length);
 }
 
 
+template <typename T>
+inline void Swizzle(T* value) {
+  char* start = reinterpret_cast<char*>(value);
+  char* end = start + sizeof(*value) - 1;
+  while (start < end) {
+    char t = *start;
+    *start++ = *end;
+    *end-- = t;
+  }
+}
+
+
+enum Endianness {
+  kLittleEndian,  // _Not_ LITTLE_ENDIAN, clashes with endian.h.
+  kBigEndian
+};
+
+
+inline enum Endianness GetEndianness() {

[Dmitry Lomov (no reviews), 2013/06/03 13:09:04]

This belongs to cpu.h. Should be a #define with possibly STATIC_ASSERT, not a
runtime function

[bnoordhuis, 2013/06/03 13:48:12]

I'll move it but is turning it into a macro necessary? It's effectively a
compile-time constant and it avoids a lot of compiler-specific #ifdefs.

[Dmitry Lomov (no reviews), 2013/06/03 14:42:49]

Explicitly define expected endianness using V8_TARGET_ARCH_ macros (see global.h
for definitions) and use STATIC_ASSERT and this set of functions to assert that
you have defined it correctly for all architectures.

+  // Constant-folded by the compiler.
+  const union {
+    uint8_t u8[2];
+    uint16_t u16;
+  } u = {
+    { 1, 0 }
+  };
+  return u.u16 == 1 ? kLittleEndian : kBigEndian;
+}
+
+
+inline bool IsLittleEndian() {
+  return GetEndianness() == kLittleEndian;
+}
+
+
+inline bool IsBigEndian() {
+  return GetEndianness() == kBigEndian;
+}
+
+
 // ----------------------------------------------------------------------------
 // BitField is a help template for encoding and decode bitfield with
 // unsigned content.
 
 template<class T, int shift, int size, class U>
 class BitFieldBase {
  public:
   // A type U mask of bit field.  To use all bits of a type U of x bits
   // in a bitfield without compiler warnings we have to compute 2^x
   // without using a shift count of x in the computation.
@@ skipping 850 matching lines @@
 
   // Every compiled stub starts with this id.
   static const int kStubEntryId = 5;
 
   int id_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_