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

1 files changed, 47 insertions, 0 deletions

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