Botan  1.10.9
bswap.h
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1 /*
2 * Byte Swapping Operations
3 * (C) 1999-2011 Jack Lloyd
4 * (C) 2007 Yves Jerschow
5 *
6 * Distributed under the terms of the Botan license
7 */
8 
9 #ifndef BOTAN_BYTE_SWAP_H__
10 #define BOTAN_BYTE_SWAP_H__
11 
12 #include <botan/types.h>
13 #include <botan/rotate.h>
14 
15 #if defined(BOTAN_TARGET_CPU_HAS_SSE2) && !defined(BOTAN_NO_SSE_INTRINSICS)
16  #include <emmintrin.h>
17 #endif
18 
19 namespace Botan {
20 
21 /**
22 * Swap a 16 bit integer
23 */
25  {
26  return rotate_left(val, 8);
27  }
28 
29 /**
30 * Swap a 32 bit integer
31 */
33  {
34 #if BOTAN_GCC_VERSION >= 430 && !defined(BOTAN_TARGET_CPU_IS_ARM_FAMILY)
35  /*
36  GCC intrinsic added in 4.3, works for a number of CPUs
37 
38  However avoid under ARM, as it branches to a function in libgcc
39  instead of generating inline asm, so slower even than the generic
40  rotate version below.
41  */
42  return __builtin_bswap32(val);
43 
44 #elif BOTAN_USE_GCC_INLINE_ASM && defined(BOTAN_TARGET_CPU_IS_X86_FAMILY)
45 
46  // GCC-style inline assembly for x86 or x86-64
47  asm("bswapl %0" : "=r" (val) : "0" (val));
48  return val;
49 
50 #elif BOTAN_USE_GCC_INLINE_ASM && defined(BOTAN_TARGET_CPU_IS_ARM_FAMILY)
51 
52  asm ("eor r3, %1, %1, ror #16\n\t"
53  "bic r3, r3, #0x00FF0000\n\t"
54  "mov %0, %1, ror #8\n\t"
55  "eor %0, %0, r3, lsr #8"
56  : "=r" (val)
57  : "0" (val)
58  : "r3", "cc");
59 
60  return val;
61 
62 #elif defined(_MSC_VER) && defined(BOTAN_TARGET_ARCH_IS_X86_32)
63 
64  // Visual C++ inline asm for 32-bit x86, by Yves Jerschow
65  __asm mov eax, val;
66  __asm bswap eax;
67 
68 #else
69 
70  // Generic implementation
71  return (rotate_right(val, 8) & 0xFF00FF00) |
72  (rotate_left (val, 8) & 0x00FF00FF);
73 
74 #endif
75  }
76 
77 /**
78 * Swap a 64 bit integer
79 */
81  {
82 #if BOTAN_GCC_VERSION >= 430
83 
84  // GCC intrinsic added in 4.3, works for a number of CPUs
85  return __builtin_bswap64(val);
86 
87 #elif BOTAN_USE_GCC_INLINE_ASM && defined(BOTAN_TARGET_ARCH_IS_X86_64)
88  // GCC-style inline assembly for x86-64
89  asm("bswapq %0" : "=r" (val) : "0" (val));
90  return val;
91 
92 #else
93  /* Generic implementation. Defined in terms of 32-bit bswap so any
94  * optimizations in that version can help here (particularly
95  * useful for 32-bit x86).
96  */
97 
98  u32bit hi = static_cast<u32bit>(val >> 32);
99  u32bit lo = static_cast<u32bit>(val);
100 
101  hi = reverse_bytes(hi);
102  lo = reverse_bytes(lo);
103 
104  return (static_cast<u64bit>(lo) << 32) | hi;
105 #endif
106  }
107 
108 /**
109 * Swap 4 Ts in an array
110 */
111 template<typename T>
112 inline void bswap_4(T x[4])
113  {
114  x[0] = reverse_bytes(x[0]);
115  x[1] = reverse_bytes(x[1]);
116  x[2] = reverse_bytes(x[2]);
117  x[3] = reverse_bytes(x[3]);
118  }
119 
120 #if defined(BOTAN_TARGET_CPU_HAS_SSE2) && !defined(BOTAN_NO_SSE_INTRINSICS)
121 
122 /**
123 * Swap 4 u32bits in an array using SSE2 shuffle instructions
124 */
125 template<>
126 inline void bswap_4(u32bit x[4])
127  {
128  __m128i T = _mm_loadu_si128(reinterpret_cast<const __m128i*>(x));
129 
130  T = _mm_shufflehi_epi16(T, _MM_SHUFFLE(2, 3, 0, 1));
131  T = _mm_shufflelo_epi16(T, _MM_SHUFFLE(2, 3, 0, 1));
132 
133  T = _mm_or_si128(_mm_srli_epi16(T, 8), _mm_slli_epi16(T, 8));
134 
135  _mm_storeu_si128(reinterpret_cast<__m128i*>(x), T);
136  }
137 
138 #endif
139 
140 }
141 
142 #endif
T rotate_left(T input, size_t rot)
Definition: rotate.h:21
unsigned long long u64bit
Definition: types.h:49
T rotate_right(T input, size_t rot)
Definition: rotate.h:34
unsigned short u16bit
Definition: types.h:27
void bswap_4(T x[4])
Definition: bswap.h:112
unsigned int u32bit
Definition: types.h:32
u16bit reverse_bytes(u16bit val)
Definition: bswap.h:24