Add utilities for converting from Host endianity to big endian and little endian formats for the va…

runtime/platform/utils_macos.h

 // Copyright (c) 2012, 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.
 
 #ifndef PLATFORM_UTILS_MACOS_H_
 #define PLATFORM_UTILS_MACOS_H_
 
+#include <libkern/OSByteOrder.h>  // NOLINT
+
 namespace dart {
 
 inline int Utils::CountTrailingZeros(uword x) {
 #if defined(ARCH_IS_32_BIT)
   return __builtin_ctzl(x);
 #elif defined(ARCH_IS_64_BIT)
   return __builtin_ctzll(x);
 #else
 #error Architecture is not 32-bit or 64-bit.
 #endif
 };
 
+
+inline uint16_t Utils::HostToBigEndian16(uint16_t value) {
+  return OSSwapHostToBigInt16(value);
+}
+
+
+inline uint32_t Utils::HostToBigEndian32(uint32_t value) {
+  return OSSwapHostToBigInt32(value);
+}
+
+
+inline uint64_t Utils::HostToBigEndian64(uint64_t value) {
+  return OSSwapHostToBigInt64(value);
+}
+
+
+inline uint16_t Utils::HostToLittleEndian16(uint16_t value) {
+  return OSSwapHostToLittleInt16(value);
+}
+
+
+inline uint32_t Utils::HostToLittleEndian32(uint32_t value) {
+  return OSSwapHostToLittleInt32(value);
+}
+
+
+inline uint64_t Utils::HostToLittleEndian64(uint64_t value) {
+  return OSSwapHostToLittleInt64(value);
+}
+
 }  // namespace dart
 
 #endif  // PLATFORM_UTILS_MACOS_H_