1 /*
2 * Word Rotation Operations
3 * (C) 1999-2008,2017 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7
8 #ifndef BOTAN_WORD_ROTATE_H_
9 #define BOTAN_WORD_ROTATE_H_
10
11 #include <botan/types.h>
12
13 BOTAN_FUTURE_INTERNAL_HEADER(rotate.h)
14
15 namespace Botan {
16
17 /**
18 * Bit rotation left by a compile-time constant amount
19 * @param input the input word
20 * @return input rotated left by ROT bits
21 */
22 template<size_t ROT, typename T>
rotl(T input)23 inline constexpr T rotl(T input)
24 {
25 static_assert(ROT > 0 && ROT < 8*sizeof(T), "Invalid rotation constant");
26 return static_cast<T>((input << ROT) | (input >> (8*sizeof(T) - ROT)));
27 }
28
29 /**
30 * Bit rotation right by a compile-time constant amount
31 * @param input the input word
32 * @return input rotated right by ROT bits
33 */
34 template<size_t ROT, typename T>
rotr(T input)35 inline constexpr T rotr(T input)
36 {
37 static_assert(ROT > 0 && ROT < 8*sizeof(T), "Invalid rotation constant");
38 return static_cast<T>((input >> ROT) | (input << (8*sizeof(T) - ROT)));
39 }
40
41 /**
42 * Bit rotation left, variable rotation amount
43 * @param input the input word
44 * @param rot the number of bits to rotate, must be between 0 and sizeof(T)*8-1
45 * @return input rotated left by rot bits
46 */
47 template<typename T>
rotl_var(T input,size_t rot)48 inline T rotl_var(T input, size_t rot)
49 {
50 return rot ? static_cast<T>((input << rot) | (input >> (sizeof(T)*8 - rot))) : input;
51 }
52
53 /**
54 * Bit rotation right, variable rotation amount
55 * @param input the input word
56 * @param rot the number of bits to rotate, must be between 0 and sizeof(T)*8-1
57 * @return input rotated right by rot bits
58 */
59 template<typename T>
rotr_var(T input,size_t rot)60 inline T rotr_var(T input, size_t rot)
61 {
62 return rot ? static_cast<T>((input >> rot) | (input << (sizeof(T)*8 - rot))) : input;
63 }
64
65 #if defined(BOTAN_USE_GCC_INLINE_ASM)
66
67 #if defined(BOTAN_TARGET_ARCH_IS_X86_64) || defined(BOTAN_TARGET_ARCH_IS_X86_32)
68
69 template<>
rotl_var(uint32_t input,size_t rot)70 inline uint32_t rotl_var(uint32_t input, size_t rot)
71 {
72 asm("roll %1,%0"
73 : "+r" (input)
74 : "c" (static_cast<uint8_t>(rot))
75 : "cc");
76 return input;
77 }
78
79 template<>
rotr_var(uint32_t input,size_t rot)80 inline uint32_t rotr_var(uint32_t input, size_t rot)
81 {
82 asm("rorl %1,%0"
83 : "+r" (input)
84 : "c" (static_cast<uint8_t>(rot))
85 : "cc");
86 return input;
87 }
88
89 #endif
90
91 #endif
92
93
94 template<typename T>
95 BOTAN_DEPRECATED("Use rotl<N> or rotl_var")
rotate_left(T input,size_t rot)96 inline T rotate_left(T input, size_t rot)
97 {
98 // rotl_var does not reduce
99 return rotl_var(input, rot % (8 * sizeof(T)));
100 }
101
102 template<typename T>
103 BOTAN_DEPRECATED("Use rotr<N> or rotr_var")
rotate_right(T input,size_t rot)104 inline T rotate_right(T input, size_t rot)
105 {
106 // rotr_var does not reduce
107 return rotr_var(input, rot % (8 * sizeof(T)));
108 }
109
110 }
111
112 #endif
113