1 files changed, 21 insertions, 12 deletions
diff --git a/src/utils/bswap.h b/src/utils/bswap.h
index 3294111a0..1a5349fd0 100644
--- a/src/utils/bswap.h
+++ b/src/utils/bswap.h
@@ -10,7 +10,7 @@
 #define BOTAN_BYTE_SWAP_H__
 
 #include <botan/types.h>
-#include <botan/internal/rotate.h>
+#include <botan/rotate.h>
 
 namespace Botan {
 
@@ -24,35 +24,44 @@ inline u16bit reverse_bytes(u16bit input)
 
 inline u32bit reverse_bytes(u32bit input)
    {
-#if BOTAN_USE_GCC_INLINE_ASM && \
-    (defined(BOTAN_TARGET_ARCH_IS_IA32) || defined(BOTAN_TARGET_ARCH_IS_AMD64))
+#if BOTAN_USE_GCC_INLINE_ASM && (defined(BOTAN_TARGET_ARCH_IS_IA32) || \
+                                 defined(BOTAN_TARGET_ARCH_IS_AMD64))
 
-   /* GCC-style inline assembly for x86 or x86-64 */
+   // GCC-style inline assembly for x86 or x86-64
    asm("bswapl %0" : "=r" (input) : "0" (input));
    return input;
 
 #elif defined(_MSC_VER) && defined(BOTAN_TARGET_ARCH_IS_IA32)
-   /* Visual C++ inline asm for 32-bit x86, by Yves Jerschow */
+   // Visual C++ inline asm for 32-bit x86, by Yves Jerschow
    __asm mov eax, input;
    __asm bswap eax;
 
 #else
-   /* Generic implementation */
-   input = ((input & 0xFF00FF00) >> 8) | ((input & 0x00FF00FF) << 8);
-   return rotate_left(input, 16);
+   // Generic implementation
+   return (rotate_right(input, 8) & 0xFF00FF00) |
+          (rotate_left (input, 8) & 0x00FF00FF);
 #endif
    }
 
 inline u64bit reverse_bytes(u64bit input)
    {
 #if BOTAN_USE_GCC_INLINE_ASM && defined(BOTAN_TARGET_ARCH_IS_AMD64)
+   // GCC-style inline assembly for x86-64
    asm("bswapq %0" : "=r" (input) : "0" (input));
    return input;
+
 #else
-   u32bit hi = ((input >> 40) & 0x00FF00FF) | ((input >> 24) & 0xFF00FF00);
-   u32bit lo = ((input & 0xFF00FF00) >> 8) | ((input & 0x00FF00FF) << 8);
-   hi = (hi << 16) | (hi >> 16);
-   lo = (lo << 16) | (lo >> 16);
+   /* Generic implementation. Defined in terms of 32-bit bswap so any
+    * optimizations in that version can help here (particularly
+    * useful for 32-bit x86).
+    */
+
+   u32bit hi = static_cast<u32bit>(input >> 32);
+   u32bit lo = static_cast<u32bit>(input);
+
+   hi = reverse_bytes(hi);
+   lo = reverse_bytes(lo);
+
    return (static_cast<u64bit>(lo) << 32) | hi;
 #endif
    }