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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_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
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
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
/* 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
}
}
#endif
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