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/*
* Byte Swapping Operations
* (C) 1999-2011 Jack Lloyd
* (C) 2007 Yves Jerschow
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_BYTE_SWAP_H_
#define BOTAN_BYTE_SWAP_H_
#include <botan/types.h>
#include <botan/rotate.h>
namespace Botan {
/**
* Swap a 16 bit integer
*/
inline uint16_t reverse_bytes(uint16_t val)
{
return rotate_left(val, 8);
}
/**
* Swap a 32 bit integer
*/
inline uint32_t reverse_bytes(uint32_t val)
{
#if BOTAN_GCC_VERSION >= 430 && !defined(BOTAN_TARGET_ARCH_IS_ARM32)
/*
GCC intrinsic added in 4.3, works for a number of CPUs
However avoid under ARM, as it branches to a function in libgcc
instead of generating inline asm, so slower even than the generic
rotate version below.
*/
return __builtin_bswap32(val);
#elif defined(BOTAN_USE_GCC_INLINE_ASM) && defined(BOTAN_TARGET_CPU_IS_X86_FAMILY)
// GCC-style inline assembly for x86 or x86-64
asm("bswapl %0" : "=r" (val) : "0" (val));
return val;
#elif defined(BOTAN_USE_GCC_INLINE_ASM) && defined(BOTAN_TARGET_ARCH_IS_ARM32)
asm ("eor r3, %1, %1, ror #16\n\t"
"bic r3, r3, #0x00FF0000\n\t"
"mov %0, %1, ror #8\n\t"
"eor %0, %0, r3, lsr #8"
: "=r" (val)
: "0" (val)
: "r3", "cc");
return val;
#elif defined(_MSC_VER) && defined(BOTAN_TARGET_ARCH_IS_X86_32)
// Visual C++ inline asm for 32-bit x86, by Yves Jerschow
__asm mov eax, val;
__asm bswap eax;
#else
// Generic implementation
return (rotate_right(val, 8) & 0xFF00FF00) |
(rotate_left (val, 8) & 0x00FF00FF);
#endif
}
/**
* Swap a 64 bit integer
*/
inline uint64_t reverse_bytes(uint64_t val)
{
#if BOTAN_GCC_VERSION >= 430
// GCC intrinsic added in 4.3, works for a number of CPUs
return __builtin_bswap64(val);
#elif defined(BOTAN_USE_GCC_INLINE_ASM) && defined(BOTAN_TARGET_ARCH_IS_X86_64)
// GCC-style inline assembly for x86-64
asm("bswapq %0" : "=r" (val) : "0" (val));
return val;
#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).
*/
uint32_t hi = static_cast<uint32_t>(val >> 32);
uint32_t lo = static_cast<uint32_t>(val);
hi = reverse_bytes(hi);
lo = reverse_bytes(lo);
return (static_cast<uint64_t>(lo) << 32) | hi;
#endif
}
/**
* Swap 4 Ts in an array
*/
template<typename T>
inline void bswap_4(T x[4])
{
x[0] = reverse_bytes(x[0]);
x[1] = reverse_bytes(x[1]);
x[2] = reverse_bytes(x[2]);
x[3] = reverse_bytes(x[3]);
}
}
#endif
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