Move net/base/sys_byteorder.h to base/sys_byteorder.h

Two motivations:
  (1) There are currently clients in src/crypto that need the same logic.
  (2) There is soon to be a client in src/chrome/common that needs the 64-bit version of this logic, which is currently inlined in a src/crypto implementation file.

BUG=103480
TEST=compiles


Review URL: http://codereview.chromium.org/8949026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@115926 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 75 insertions, 0 deletions

diff --git a/base/sys_byteorder.h b/base/sys_byteorder.h
new file mode 100644
index 0000000..9fcdbba
--- /dev/null
+++ b/base/sys_byteorder.h
@@ -0,0 +1,75 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This is a convenience header to pull in the platform-specific
+// headers that define functions for byte-order conversion,
+// particularly: ntohs(), htons(), ntohl(), htonl(). Prefer including
+// this file instead of directly writing the #if / #else, since it
+// avoids duplicating the platform-specific selections.
+// This header also provides ntohll() and htonll() for byte-order conversion
+// for 64-bit integers.
+
+#ifndef BASE_SYS_BYTEORDER_H_
+#define BASE_SYS_BYTEORDER_H_
+
+#include "base/basictypes.h"
+#include "build/build_config.h"
+
+#if defined(OS_WIN)
+#include <winsock2.h>
+#else
+#include <arpa/inet.h>
+#endif
+
+// Include headers to provide byteswap for all platforms.
+#if defined(COMPILER_MSVC)
+#include <stdlib.h>
+#elif defined(OS_MACOSX)
+#include <libkern/OSByteOrder.h>
+#elif defined(OS_OPENBSD)
+#include <sys/endian.h>
+#else
+#include <byteswap.h>
+#endif
+
+
+namespace base {
+
+// Returns a value with all bytes in |x| swapped, i.e. reverses the endianness.
+inline uint64 ByteSwap(uint64 x) {
+#if defined(COMPILER_MSVC)
+  return _byteswap_uint64(x);
+#elif defined(OS_MACOSX)
+  return OSSwapInt64(x);
+#elif defined(OS_OPENBSD)
+  return swap64(x);
+#else
+  return bswap_64(x);
+#endif
+}
+
+// Converts the bytes in |x| from network to host order (endianness), and
+// returns the result.
+inline uint64 ntohll(uint64 x) {
+#if defined(ARCH_CPU_LITTLE_ENDIAN)
+  return ByteSwap(x);
+#else
+  return x;
+#endif
+}
+
+// Converts the bytes in |x| from host to network order (endianness), and
+// returns the result.
+inline uint64 htonll(uint64 x) {
+#if defined(ARCH_CPU_LITTLE_ENDIAN)
+  return ByteSwap(x);
+#else
+  return x;
+#endif
+}
+
+}  // namespace base
+
+
+#endif  // BASE_SYS_BYTEORDER_H_