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/*
* Byte Swapping Operations
* (C) 1999-2011 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>
#if defined(BOTAN_TARGET_CPU_HAS_SSE2) && !defined(BOTAN_NO_SSE_INTRINSICS)
#include <emmintrin.h>
#endif
namespace Botan {
/**
* Swap a 16 bit integer
*/
inline u16bit reverse_bytes(u16bit val)
{
return rotate_left(val, 8);
}
/**
* Swap a 32 bit integer
*/
inline u32bit reverse_bytes(u32bit val)
{
#if BOTAN_GCC_VERSION >= 430 && !defined(BOTAN_TARGET_CPU_IS_ARM_FAMILY)
/*
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 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 BOTAN_USE_GCC_INLINE_ASM && defined(BOTAN_TARGET_CPU_IS_ARM_FAMILY)
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_IA32)
// 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 u64bit reverse_bytes(u64bit val)
{
#if BOTAN_GCC_VERSION >= 430
// GCC intrinsic added in 4.3, works for a number of CPUs
return __builtin_bswap64(val);
#elif BOTAN_USE_GCC_INLINE_ASM && defined(BOTAN_TARGET_ARCH_IS_AMD64)
// 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).
*/
u32bit hi = static_cast<u32bit>(val >> 32);
u32bit lo = static_cast<u32bit>(val);
hi = reverse_bytes(hi);
lo = reverse_bytes(lo);
return (static_cast<u64bit>(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]);
}
#if defined(BOTAN_TARGET_CPU_HAS_SSE2) && !defined(BOTAN_NO_SSE_INTRINSICS)
/**
* Swap 4 u32bits in an array using SSE2 shuffle instructions
*/
template<>
inline void bswap_4(u32bit x[4])
{
__m128i T = _mm_loadu_si128(reinterpret_cast<const __m128i*>(x));
T = _mm_shufflehi_epi16(T, _MM_SHUFFLE(2, 3, 0, 1));
T = _mm_shufflelo_epi16(T, _MM_SHUFFLE(2, 3, 0, 1));
T = _mm_or_si128(_mm_srli_epi16(T, 8), _mm_slli_epi16(T, 8));
_mm_storeu_si128(reinterpret_cast<__m128i*>(x), T);
}
#endif
}
#endif
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