v8 typed arrays: add DataView type

src/utils.h

Index: src/utils.h
diff --git a/src/utils.h b/src/utils.h
index b16730b8c46d750c1e264ad07713868c2b32d804..50af2597c7d00866f57da223a086f3acda35dddb 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -246,6 +246,46 @@ inline int StrLength(const char* string) {
 }
 
 
+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.