Use native (optimized) functions for byte order conversion.

webrtc/base/byteorder.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_BASE_BYTEORDER_H_
 #define WEBRTC_BASE_BYTEORDER_H_
 
 #if defined(WEBRTC_POSIX) && !defined(__native_client__)
 #include <arpa/inet.h>
 #endif
 
-#if defined(WEBRTC_WIN)
-#include <stdlib.h>
-#endif
-
 #include "webrtc/base/basictypes.h"

[joachim, 2017/03/09 23:36:53]

Moved here so the "RTC_ARCH_CPU_" defines are available below.

[tommi, 2017/03/16 16:37:02]

Acknowledged.

 
+#if defined(WEBRTC_MAC)
+#include <libkern/OSByteOrder.h>
+
+#define htobe16(v) OSSwapHostToBigInt16(v)
+#define htobe32(v) OSSwapHostToBigInt32(v)
+#define htobe64(v) OSSwapHostToBigInt64(v)
+#define be16toh(v) OSSwapBigToHostInt16(v)
+#define be32toh(v) OSSwapBigToHostInt32(v)
+#define be64toh(v) OSSwapBigToHostInt64(v)
+
+#define htole16(v) OSSwapHostToLittleInt16(v)
+#define htole32(v) OSSwapHostToLittleInt32(v)
+#define htole64(v) OSSwapHostToLittleInt64(v)
+#define le16toh(v) OSSwapLittleToHostInt16(v)
+#define le32toh(v) OSSwapLittleToHostInt32(v)
+#define le64toh(v) OSSwapLittleToHostInt64(v)
+#elif defined(WEBRTC_POSIX)
+#include <endian.h>
+#elif defined(WEBRTC_WIN)
+#include <stdlib.h>
+#include <winsock2.h>
+
+#define htobe16(v) htons(v)
+#define htobe32(v) htonl(v)
+#define htobe64(v) htonll(v)
+#define be16toh(v) ntohs(v)
+#define be32toh(v) ntohl(v)
+#define be64toh(v) ntohll(v)
+
+#if defined(RTC_ARCH_CPU_LITTLE_ENDIAN)

[joachim, 2017/03/09 23:36:53]

To simplify things we could assume Windows is always little endian (which should
almost always be the case). This code explicitly supports both.

[tommi, 2017/03/16 16:37:02]

Acknowledged.

+#define htole16(v) (v)
+#define htole32(v) (v)
+#define htole64(v) (v)
+#define le16toh(v) (v)
+#define le32toh(v) (v)
+#define le64toh(v) (v)
+#elif defined(RTC_ARCH_CPU_BIG_ENDIAN)
+#define htole16(v) __builtin_bswap16(v)
+#define htole32(v) __builtin_bswap32(v)
+#define htole64(v) __builtin_bswap64(v)
+#define le16toh(v) __builtin_bswap16(v)
+#define le32toh(v) __builtin_bswap32(v)
+#define le64toh(v) __builtin_bswap64(v)
+#else
+#error RTC_ARCH_CPU_BIG_ENDIAN or RTC_ARCH_CPU_LITTLE_ENDIAN must be defined.
+#endif
+
+#endif  // defined(WEBRTC_WIN)
+
 namespace rtc {
 
 // Reading and writing of little and big-endian numbers from memory
-// TODO: Optimized versions, with direct read/writes of
-// integers in host-endian format, when the platform supports it.
 
 inline void Set8(void* memory, size_t offset, uint8_t v) {
   static_cast<uint8_t*>(memory)[offset] = v;
 }
 
 inline uint8_t Get8(const void* memory, size_t offset) {
   return static_cast<const uint8_t*>(memory)[offset];
 }
 
 inline void SetBE16(void* memory, uint16_t v) {
-  Set8(memory, 0, static_cast<uint8_t>(v >> 8));
-  Set8(memory, 1, static_cast<uint8_t>(v >> 0));
+  *static_cast<uint16_t*>(memory) = htobe16(v);
 }
 
 inline void SetBE32(void* memory, uint32_t v) {
-  Set8(memory, 0, static_cast<uint8_t>(v >> 24));
-  Set8(memory, 1, static_cast<uint8_t>(v >> 16));
-  Set8(memory, 2, static_cast<uint8_t>(v >> 8));
-  Set8(memory, 3, static_cast<uint8_t>(v >> 0));
+  *static_cast<uint32_t*>(memory) = htobe32(v);
 }
 
 inline void SetBE64(void* memory, uint64_t v) {
-  Set8(memory, 0, static_cast<uint8_t>(v >> 56));
-  Set8(memory, 1, static_cast<uint8_t>(v >> 48));
-  Set8(memory, 2, static_cast<uint8_t>(v >> 40));
-  Set8(memory, 3, static_cast<uint8_t>(v >> 32));
-  Set8(memory, 4, static_cast<uint8_t>(v >> 24));
-  Set8(memory, 5, static_cast<uint8_t>(v >> 16));
-  Set8(memory, 6, static_cast<uint8_t>(v >> 8));
-  Set8(memory, 7, static_cast<uint8_t>(v >> 0));
+  *static_cast<uint64_t*>(memory) = htobe64(v);
 }
 
 inline uint16_t GetBE16(const void* memory) {
-  return static_cast<uint16_t>((Get8(memory, 0) << 8) | (Get8(memory, 1) << 0));
+  return be16toh(*static_cast<const uint16_t*>(memory));
 }
 
 inline uint32_t GetBE32(const void* memory) {
-  return (static_cast<uint32_t>(Get8(memory, 0)) << 24) |
-         (static_cast<uint32_t>(Get8(memory, 1)) << 16) |
-         (static_cast<uint32_t>(Get8(memory, 2)) << 8) |
-         (static_cast<uint32_t>(Get8(memory, 3)) << 0);
+  return be32toh(*static_cast<const uint32_t*>(memory));
 }
 
 inline uint64_t GetBE64(const void* memory) {
-  return (static_cast<uint64_t>(Get8(memory, 0)) << 56) |
-         (static_cast<uint64_t>(Get8(memory, 1)) << 48) |
-         (static_cast<uint64_t>(Get8(memory, 2)) << 40) |
-         (static_cast<uint64_t>(Get8(memory, 3)) << 32) |
-         (static_cast<uint64_t>(Get8(memory, 4)) << 24) |
-         (static_cast<uint64_t>(Get8(memory, 5)) << 16) |
-         (static_cast<uint64_t>(Get8(memory, 6)) << 8) |
-         (static_cast<uint64_t>(Get8(memory, 7)) << 0);
+  return be64toh(*static_cast<const uint64_t*>(memory));
 }
 
 inline void SetLE16(void* memory, uint16_t v) {
-  Set8(memory, 0, static_cast<uint8_t>(v >> 0));
-  Set8(memory, 1, static_cast<uint8_t>(v >> 8));
+  *static_cast<uint16_t*>(memory) = htole16(v);
 }
 
 inline void SetLE32(void* memory, uint32_t v) {
-  Set8(memory, 0, static_cast<uint8_t>(v >> 0));
-  Set8(memory, 1, static_cast<uint8_t>(v >> 8));
-  Set8(memory, 2, static_cast<uint8_t>(v >> 16));
-  Set8(memory, 3, static_cast<uint8_t>(v >> 24));
+  *static_cast<uint32_t*>(memory) = htole32(v);
 }
 
 inline void SetLE64(void* memory, uint64_t v) {
-  Set8(memory, 0, static_cast<uint8_t>(v >> 0));
-  Set8(memory, 1, static_cast<uint8_t>(v >> 8));
-  Set8(memory, 2, static_cast<uint8_t>(v >> 16));
-  Set8(memory, 3, static_cast<uint8_t>(v >> 24));
-  Set8(memory, 4, static_cast<uint8_t>(v >> 32));
-  Set8(memory, 5, static_cast<uint8_t>(v >> 40));
-  Set8(memory, 6, static_cast<uint8_t>(v >> 48));
-  Set8(memory, 7, static_cast<uint8_t>(v >> 56));
+  *static_cast<uint64_t*>(memory) = htole64(v);
 }
 
 inline uint16_t GetLE16(const void* memory) {
-  return static_cast<uint16_t>((Get8(memory, 0) << 0) | (Get8(memory, 1) << 8));
+  return le16toh(*static_cast<const uint16_t*>(memory));
 }
 
 inline uint32_t GetLE32(const void* memory) {
-  return (static_cast<uint32_t>(Get8(memory, 0)) << 0) |
-         (static_cast<uint32_t>(Get8(memory, 1)) << 8) |
-         (static_cast<uint32_t>(Get8(memory, 2)) << 16) |
-         (static_cast<uint32_t>(Get8(memory, 3)) << 24);
+  return le32toh(*static_cast<const uint32_t*>(memory));
 }
 
 inline uint64_t GetLE64(const void* memory) {
-  return (static_cast<uint64_t>(Get8(memory, 0)) << 0) |
-         (static_cast<uint64_t>(Get8(memory, 1)) << 8) |
-         (static_cast<uint64_t>(Get8(memory, 2)) << 16) |
-         (static_cast<uint64_t>(Get8(memory, 3)) << 24) |
-         (static_cast<uint64_t>(Get8(memory, 4)) << 32) |
-         (static_cast<uint64_t>(Get8(memory, 5)) << 40) |
-         (static_cast<uint64_t>(Get8(memory, 6)) << 48) |
-         (static_cast<uint64_t>(Get8(memory, 7)) << 56);
+  return le64toh(*static_cast<const uint64_t*>(memory));
 }
 
 // Check if the current host is big endian.
 inline bool IsHostBigEndian() {
-  static const int number = 1;
-  return 0 == *reinterpret_cast<const char*>(&number);
+#if defined(RTC_ARCH_CPU_BIG_ENDIAN)
+  return true;
+#else
+  return false;
+#endif
 }
 
 inline uint16_t HostToNetwork16(uint16_t n) {
-  uint16_t result;
-  SetBE16(&result, n);
-  return result;
+  return htobe16(n);
 }
 
 inline uint32_t HostToNetwork32(uint32_t n) {
-  uint32_t result;
-  SetBE32(&result, n);
-  return result;
+  return htobe32(n);
 }
 
 inline uint64_t HostToNetwork64(uint64_t n) {
-  uint64_t result;
-  SetBE64(&result, n);
-  return result;
+  return htobe64(n);
 }
 
 inline uint16_t NetworkToHost16(uint16_t n) {
-  return GetBE16(&n);
+  return be16toh(n);
 }
 
 inline uint32_t NetworkToHost32(uint32_t n) {
-  return GetBE32(&n);
+  return be32toh(n);
 }
 
 inline uint64_t NetworkToHost64(uint64_t n) {
-  return GetBE64(&n);
+  return be64toh(n);
 }
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_BYTEORDER_H_