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/*
* Byte Swapping Operations
* (C) 1999-2008 Jack Lloyd
* (C) 2007 Yves Jerschow
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_BYTE_SWAP_H__
#define BOTAN_BYTE_SWAP_H__
#include <botan/types.h>
#include <botan/rotate.h>
namespace Botan {
/*
* Byte Swapping Functions
*/
inline u16bit reverse_bytes(u16bit input)
{
return rotate_left(input, 8);
}
inline u32bit reverse_bytes(u32bit input)
{
#if BOTAN_COMPILER_HAS_GCC_INLINE_ASM && \
(defined(BOTAN_TARGET_ARCH_IS_IA32) || defined(BOTAN_TARGET_ARCH_IS_AMD64))
/* 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 */
__asm mov eax, input;
__asm bswap eax;
#else
/* Generic implementation */
input = ((input & 0xFF00FF00) >> 8) | ((input & 0x00FF00FF) << 8);
return rotate_left(input, 16);
#endif
}
inline u64bit reverse_bytes(u64bit input)
{
#if BOTAN_COMPILER_HAS_GCC_INLINE_ASM && defined(BOTAN_TARGET_ARCH_IS_AMD64)
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);
return (static_cast<u64bit>(lo) << 32) | hi;
#endif
}
}
#endif
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