build: Endian compatibility

- Detect endian instead of stopping configure on big-endian
- Add `byteswap.h` and `endian.h` header for compatibility with
  Windows and other operating systems that don't come with them
- Update `crypto/common.h` functions to use compat
  endian header

5 files changed, 263 insertions, 69 deletions

diff --git a/configure.ac b/configure.ac
index f5bc1e3122..2c918218bb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -350,8 +350,8 @@ if test x$use_lcov = xyes; then
     [AC_MSG_ERROR("lcov testing requested but --coverage flag does not work")])
 fi
 
-dnl Require little endian
-AC_C_BIGENDIAN([AC_MSG_ERROR("Big Endian not supported")])
+dnl Check for endianness
+AC_C_BIGENDIAN
 
 dnl Check for pthread compile/link requirements
 AX_PTHREAD
@@ -438,17 +438,22 @@ if test x$TARGET_OS = xdarwin; then
   AX_CHECK_LINK_FLAG([[-Wl,-dead_strip]], [LDFLAGS="$LDFLAGS -Wl,-dead_strip"])
 fi
 
-AC_CHECK_HEADERS([endian.h stdio.h stdlib.h unistd.h strings.h sys/types.h sys/stat.h sys/select.h sys/prctl.h])
+AC_CHECK_HEADERS([endian.h byteswap.h stdio.h stdlib.h unistd.h strings.h sys/types.h sys/stat.h sys/select.h sys/prctl.h])
 AC_SEARCH_LIBS([getaddrinfo_a], [anl], [AC_DEFINE(HAVE_GETADDRINFO_A, 1, [Define this symbol if you have getaddrinfo_a])])
 AC_SEARCH_LIBS([inet_pton], [nsl resolv], [AC_DEFINE(HAVE_INET_PTON, 1, [Define this symbol if you have inet_pton])])
 
 AC_CHECK_DECLS([strnlen])
 
-AC_CHECK_DECLS([le32toh, le64toh, htole32, htole64, be32toh, be64toh, htobe32, htobe64],,,
+AC_CHECK_DECLS([le16toh, le32toh, le64toh, htole16, htole32, htole64, be16toh, be32toh, be64toh, htobe16, htobe32, htobe64],,,
 		[#if HAVE_ENDIAN_H
                  #include <endian.h>
                  #endif])
 
+AC_CHECK_DECLS([bswap_16, bswap_32, bswap_64],,,
+		[#if HAVE_BYTESWAP_H
+                 #include <byteswap.h>
+                 #endif])
+
 dnl Check for MSG_NOSIGNAL
 AC_MSG_CHECKING(for MSG_NOSIGNAL)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/socket.h>]],
diff --git a/src/Makefile.am b/src/Makefile.am
index e1d467ff85..da65efa713 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -141,6 +141,8 @@ BITCOIN_CORE_H = \
   walletdb.h \
   wallet.h \
   wallet_ismine.h \
+  compat/byteswap.h \
+  compat/endian.h \
   compat/sanity.h
 
 JSON_H = \
diff --git a/src/compat/byteswap.h b/src/compat/byteswap.h
new file mode 100644
index 0000000000..899220bdc5
--- /dev/null
+++ b/src/compat/byteswap.h
@@ -0,0 +1,47 @@
+// Copyright (c) 2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_COMPAT_BYTESWAP_H
+#define BITCOIN_COMPAT_BYTESWAP_H
+
+#if defined(HAVE_CONFIG_H)
+#include "config/bitcoin-config.h"
+#endif
+
+#include <stdint.h>
+
+#if defined(HAVE_BYTESWAP_H)
+#include <byteswap.h>
+#endif
+
+#if HAVE_DECL_BSWAP_16 == 0
+inline uint16_t bswap_16(uint16_t x)
+{
+    return (x >> 8) | ((x & 0x00ff) << 8);
+}
+#endif // HAVE_DECL_BSWAP16
+
+#if HAVE_DECL_BSWAP_32 == 0
+inline uint32_t bswap_32(uint32_t x)
+{
+    return (((x & 0xff000000U) >> 24) | ((x & 0x00ff0000U) >>  8) |
+            ((x & 0x0000ff00U) <<  8) | ((x & 0x000000ffU) << 24));
+}
+#endif // HAVE_DECL_BSWAP32
+
+#if HAVE_DECL_BSWAP_64 == 0
+inline uint64_t bswap_64(uint64_t x)
+{
+     return (((x & 0xff00000000000000ull) >> 56)
+          | ((x & 0x00ff000000000000ull) >> 40)
+          | ((x & 0x0000ff0000000000ull) >> 24)
+          | ((x & 0x000000ff00000000ull) >> 8)
+          | ((x & 0x00000000ff000000ull) << 8)
+          | ((x & 0x0000000000ff0000ull) << 24)
+          | ((x & 0x000000000000ff00ull) << 40)
+          | ((x & 0x00000000000000ffull) << 56));
+}
+#endif // HAVE_DECL_BSWAP64
+
+#endif // BITCOIN_COMPAT_BYTESWAP_H
diff --git a/src/compat/endian.h b/src/compat/endian.h
new file mode 100644
index 0000000000..4d041d6554
--- /dev/null
+++ b/src/compat/endian.h
@@ -0,0 +1,194 @@
+// Copyright (c) 2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_COMPAT_ENDIAN_H
+#define BITCOIN_COMPAT_ENDIAN_H
+
+#if defined(HAVE_CONFIG_H)
+#include "config/bitcoin-config.h"
+#endif
+
+#include <stdint.h>
+
+#include "compat/byteswap.h"
+
+#if defined(HAVE_ENDIAN_H)
+#include <endian.h>
+#endif
+
+#if defined(WORDS_BIGENDIAN)
+
+#if HAVE_DECL_HTOBE16 == 0
+inline uint16_t htobe16(uint16_t host_16bits)
+{
+    return host_16bits;
+}
+#endif // HAVE_DECL_HTOBE16
+
+#if HAVE_DECL_HTOLE16 == 0
+inline uint16_t htole16(uint16_t host_16bits)
+{
+    return bswap_16(host_16bits);
+}
+#endif // HAVE_DECL_HTOLE16
+
+#if HAVE_DECL_BE16TOH == 0
+inline uint16_t be16toh(uint16_t big_endian_16bits)
+{
+    return big_endian_16bits;
+}
+#endif // HAVE_DECL_BE16TOH
+
+#if HAVE_DECL_LE16TOH == 0
+inline uint16_t le16toh(uint16_t little_endian_16bits)
+{
+    return bswap_16(little_endian_16bits);
+}
+#endif // HAVE_DECL_LE16TOH
+
+#if HAVE_DECL_HTOBE32 == 0
+inline uint32_t htobe32(uint32_t host_32bits)
+{
+    return host_32bits;
+}
+#endif // HAVE_DECL_HTOBE32
+
+#if HAVE_DECL_HTOLE32 == 0
+inline uint32_t htole32(uint32_t host_32bits)
+{
+    return bswap_32(host_32bits);
+}
+#endif // HAVE_DECL_HTOLE32
+
+#if HAVE_DECL_BE32TOH == 0
+inline uint32_t be32toh(uint32_t big_endian_32bits)
+{
+    return big_endian_32bits;
+}
+#endif // HAVE_DECL_BE32TOH
+
+#if HAVE_DECL_LE32TOH == 0
+inline uint32_t le32toh(uint32_t little_endian_32bits)
+{
+    return bswap_32(little_endian_32bits);
+}
+#endif // HAVE_DECL_LE32TOH
+
+#if HAVE_DECL_HTOBE64 == 0
+inline uint64_t htobe64(uint64_t host_64bits)
+{
+    return host_64bits;
+}
+#endif // HAVE_DECL_HTOBE64
+
+#if HAVE_DECL_HTOLE64 == 0
+inline uint64_t htole64(uint64_t host_64bits)
+{
+    return bswap_64(host_64bits);
+}
+#endif // HAVE_DECL_HTOLE64
+
+#if HAVE_DECL_BE64TOH == 0
+inline uint64_t be64toh(uint64_t big_endian_64bits)
+{
+    return big_endian_64bits;
+}
+#endif // HAVE_DECL_BE64TOH
+
+#if HAVE_DECL_LE64TOH == 0
+inline uint64_t le64toh(uint64_t little_endian_64bits)
+{
+    return bswap_64(little_endian_64bits);
+}
+#endif // HAVE_DECL_LE64TOH
+
+#else // WORDS_BIGENDIAN
+
+#if HAVE_DECL_HTOBE16 == 0
+inline uint16_t htobe16(uint16_t host_16bits)
+{
+    return bswap_16(host_16bits);
+}
+#endif // HAVE_DECL_HTOBE16
+
+#if HAVE_DECL_HTOLE16 == 0
+inline uint16_t htole16(uint16_t host_16bits)
+{
+    return host_16bits;
+}
+#endif // HAVE_DECL_HTOLE16
+
+#if HAVE_DECL_BE16TOH == 0
+inline uint16_t be16toh(uint16_t big_endian_16bits)
+{
+    return bswap_16(big_endian_16bits);
+}
+#endif // HAVE_DECL_BE16TOH
+
+#if HAVE_DECL_LE16TOH == 0
+inline uint16_t le16toh(uint16_t little_endian_16bits)
+{
+    return little_endian_16bits;
+}
+#endif // HAVE_DECL_LE16TOH
+
+#if HAVE_DECL_HTOBE32 == 0
+inline uint32_t htobe32(uint32_t host_32bits)
+{
+    return bswap_32(host_32bits);
+}
+#endif // HAVE_DECL_HTOBE32
+
+#if HAVE_DECL_HTOLE32 == 0
+inline uint32_t htole32(uint32_t host_32bits)
+{
+    return host_32bits;
+}
+#endif // HAVE_DECL_HTOLE32
+
+#if HAVE_DECL_BE32TOH == 0
+inline uint32_t be32toh(uint32_t big_endian_32bits)
+{
+    return bswap_32(big_endian_32bits);
+}
+#endif // HAVE_DECL_BE32TOH
+
+#if HAVE_DECL_LE32TOH == 0
+inline uint32_t le32toh(uint32_t little_endian_32bits)
+{
+    return little_endian_32bits;
+}
+#endif // HAVE_DECL_LE32TOH
+
+#if HAVE_DECL_HTOBE64 == 0
+inline uint64_t htobe64(uint64_t host_64bits)
+{
+    return bswap_64(host_64bits);
+}
+#endif // HAVE_DECL_HTOBE64
+
+#if HAVE_DECL_HTOLE64 == 0
+inline uint64_t htole64(uint64_t host_64bits)
+{
+    return host_64bits;
+}
+#endif // HAVE_DECL_HTOLE64
+
+#if HAVE_DECL_BE64TOH == 0
+inline uint64_t be64toh(uint64_t big_endian_64bits)
+{
+    return bswap_64(big_endian_64bits);
+}
+#endif // HAVE_DECL_BE64TOH
+
+#if HAVE_DECL_LE64TOH == 0
+inline uint64_t le64toh(uint64_t little_endian_64bits)
+{
+    return little_endian_64bits;
+}
+#endif // HAVE_DECL_LE64TOH
+
+#endif // WORDS_BIGENDIAN
+
+#endif // BITCOIN_COMPAT_ENDIAN_H
diff --git a/src/crypto/common.h b/src/crypto/common.h
index 8b04b1f728..580c72f5a6 100644
--- a/src/crypto/common.h
+++ b/src/crypto/common.h
@@ -11,110 +11,56 @@
 
 #include <stdint.h>
 
-#if defined(HAVE_ENDIAN_H)
-#include <endian.h>
-#endif
+#include "compat/endian.h"
+
+uint16_t static inline ReadLE16(const unsigned char* ptr)
+{
+    return le16toh(*((uint16_t*)ptr));
+}
 
 uint32_t static inline ReadLE32(const unsigned char* ptr)
 {
-#if HAVE_DECL_LE32TOH == 1
     return le32toh(*((uint32_t*)ptr));
-#elif !defined(WORDS_BIGENDIAN)
-    return *((uint32_t*)ptr);
-#else
-    return ((uint32_t)ptr[3] << 24 | (uint32_t)ptr[2] << 16 | (uint32_t)ptr[1] << 8 | (uint32_t)ptr[0]);
-#endif
 }
 
 uint64_t static inline ReadLE64(const unsigned char* ptr)
 {
-#if HAVE_DECL_LE64TOH == 1
     return le64toh(*((uint64_t*)ptr));
-#elif !defined(WORDS_BIGENDIAN)
-    return *((uint64_t*)ptr);
-#else
-    return ((uint64_t)ptr[7] << 56 | (uint64_t)ptr[6] << 48 | (uint64_t)ptr[5] << 40 | (uint64_t)ptr[4] << 32 |
-            (uint64_t)ptr[3] << 24 | (uint64_t)ptr[2] << 16 | (uint64_t)ptr[1] << 8 | (uint64_t)ptr[0]);
-#endif
+}
+
+void static inline WriteLE16(unsigned char* ptr, uint16_t x)
+{
+    *((uint16_t*)ptr) = htole16(x);
 }
 
 void static inline WriteLE32(unsigned char* ptr, uint32_t x)
 {
-#if HAVE_DECL_HTOLE32 == 1
     *((uint32_t*)ptr) = htole32(x);
-#elif !defined(WORDS_BIGENDIAN)
-    *((uint32_t*)ptr) = x;
-#else
-    ptr[3] = x >> 24;
-    ptr[2] = x >> 16;
-    ptr[1] = x >> 8;
-    ptr[0] = x;
-#endif
 }
 
 void static inline WriteLE64(unsigned char* ptr, uint64_t x)
 {
-#if HAVE_DECL_HTOLE64 == 1
     *((uint64_t*)ptr) = htole64(x);
-#elif !defined(WORDS_BIGENDIAN)
-    *((uint64_t*)ptr) = x;
-#else
-    ptr[7] = x >> 56;
-    ptr[6] = x >> 48;
-    ptr[5] = x >> 40;
-    ptr[4] = x >> 32;
-    ptr[3] = x >> 24;
-    ptr[2] = x >> 16;
-    ptr[1] = x >> 8;
-    ptr[0] = x;
-#endif
 }
 
 uint32_t static inline ReadBE32(const unsigned char* ptr)
 {
-#if HAVE_DECL_BE32TOH == 1
     return be32toh(*((uint32_t*)ptr));
-#else
-    return ((uint32_t)ptr[0] << 24 | (uint32_t)ptr[1] << 16 | (uint32_t)ptr[2] << 8 | (uint32_t)ptr[3]);
-#endif
 }
 
 uint64_t static inline ReadBE64(const unsigned char* ptr)
 {
-#if HAVE_DECL_BE64TOH == 1
     return be64toh(*((uint64_t*)ptr));
-#else
-    return ((uint64_t)ptr[0] << 56 | (uint64_t)ptr[1] << 48 | (uint64_t)ptr[2] << 40 | (uint64_t)ptr[3] << 32 |
-            (uint64_t)ptr[4] << 24 | (uint64_t)ptr[5] << 16 | (uint64_t)ptr[6] << 8 | (uint64_t)ptr[7]);
-#endif
 }
 
 void static inline WriteBE32(unsigned char* ptr, uint32_t x)
 {
-#if HAVE_DECL_HTOBE32 == 1
     *((uint32_t*)ptr) = htobe32(x);
-#else
-    ptr[0] = x >> 24;
-    ptr[1] = x >> 16;
-    ptr[2] = x >> 8;
-    ptr[3] = x;
-#endif
 }
 
 void static inline WriteBE64(unsigned char* ptr, uint64_t x)
 {
-#if HAVE_DECL_HTOBE64 == 1
     *((uint64_t*)ptr) = htobe64(x);
-#else
-    ptr[0] = x >> 56;
-    ptr[1] = x >> 48;
-    ptr[2] = x >> 40;
-    ptr[3] = x >> 32;
-    ptr[4] = x >> 24;
-    ptr[5] = x >> 16;
-    ptr[6] = x >> 8;
-    ptr[7] = x;
-#endif
 }
 
 #endif // BITCOIN_CRYPTO_COMMON_H