Crypto++ 8.4 Free C++ class library of cryptographic schemes

words.h
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1 // words.h - originally written and placed in the public domain by Wei Dai
2
3 /// \file words.h
4 /// \brief Support functions for word operations
5
6 #ifndef CRYPTOPP_WORDS_H
7 #define CRYPTOPP_WORDS_H
8
9 #include "config.h"
10 #include "misc.h"
11
12 NAMESPACE_BEGIN(CryptoPP)
13
14 /// \brief Count the number of words
15 /// \param x word array
16 /// \param n size of the word array, in elements
17 /// \return number of words used in the array.
18 /// \details CountWords counts the number of words in a word array.
19 /// Leading 0-words are not included in the count.
20 /// \since Crypto++ 1.0
21 inline size_t CountWords(const word *x, size_t n)
22 {
23 while (n && x[n-1]==0)
24 n--;
25 return n;
26 }
27
28 /// \brief Set the value of words
29 /// \param r word array
30 /// \param a value
31 /// \param n size of the word array, in elements
32 /// \details SetWords sets all elements in the word array to the
33 /// specified value.
34 /// \since Crypto++ 1.0
35 inline void SetWords(word *r, word a, size_t n)
36 {
37 for (size_t i=0; i<n; i++)
38 r[i] = a;
39 }
40
41 /// \brief Copy word array
42 /// \param r destination word array
43 /// \param a source word array
44 /// \param n size of the word array, in elements
45 /// \details CopyWords copies the source word array to the destination
46 /// word array.
47 /// \since Crypto++ 1.0
48 inline void CopyWords(word *r, const word *a, size_t n)
49 {
50 if (r != a)
51 #if CRYPTOPP_MSC_VERSION
52 memcpy_s(r, n*WORD_SIZE, a, n*WORD_SIZE);
53 #else
54 memcpy(r, a, n*WORD_SIZE);
55 #endif
56 }
57
58 /// \brief XOR word arrays
59 /// \param r destination word array
60 /// \param a first source word array
61 /// \param b second source word array
62 /// \param n size of the word array, in elements
63 /// \details XorWords XORs the two source word arrays and copies the
64 /// result to the destination word array.
65 /// \since Crypto++ 1.0
66 inline void XorWords(word *r, const word *a, const word *b, size_t n)
67 {
68 for (size_t i=0; i<n; i++)
69 r[i] = a[i] ^ b[i];
70 }
71
72 /// \brief XOR word arrays
73 /// \param r destination word array
74 /// \param a source word array
75 /// \param n size of the word array, in elements
76 /// \details XorWords XORs the source word array with the
77 /// destination word array.
78 /// \since Crypto++ 1.0
79 inline void XorWords(word *r, const word *a, size_t n)
80 {
81 for (size_t i=0; i<n; i++)
82 r[i] ^= a[i];
83 }
84
85 /// \brief AND word arrays
86 /// \param r destination word array
87 /// \param a first source word array
88 /// \param b second source word array
89 /// \param n size of the word array, in elements
90 /// \details AndWords ANDs the two source word arrays and copies the
91 /// result to the destination word array.
92 /// \since Crypto++ 1.0
93 inline void AndWords(word *r, const word *a, const word *b, size_t n)
94 {
95 for (size_t i=0; i<n; i++)
96 r[i] = a[i] & b[i];
97 }
98
99 /// \brief AND word arrays
100 /// \param r destination word array
101 /// \param a source word array
102 /// \param n size of the word array, in elements
103 /// \details AndWords ANDs the source word array with the
104 /// destination word array.
105 /// \since Crypto++ 1.0
106 inline void AndWords(word *r, const word *a, size_t n)
107 {
108 for (size_t i=0; i<n; i++)
109 r[i] &= a[i];
110 }
111
112 /// \brief OR word arrays
113 /// \param r destination word array
114 /// \param a first source word array
115 /// \param b second source word array
116 /// \param n size of the word array, in elements
117 /// \details OrWords ORs the two source word arrays and copies the
118 /// result to the destination word array.
119 /// \since Crypto++ 1.0
120 inline void OrWords(word *r, const word *a, const word *b, size_t n)
121 {
122 for (size_t i=0; i<n; i++)
123 r[i] = a[i] | b[i];
124 }
125
126 /// \brief OR word arrays
127 /// \param r destination word array
128 /// \param a source word array
129 /// \param n size of the word array, in elements
130 /// \details OrWords ORs the source word array with the
131 /// destination word array.
132 /// \since Crypto++ 1.0
133 inline void OrWords(word *r, const word *a, size_t n)
134 {
135 for (size_t i=0; i<n; i++)
136 r[i] |= a[i];
137 }
138
139 /// \brief Left shift word array
140 /// \param r word array
141 /// \param n size of the word array, in elements
142 /// \param shiftBits number of bits to shift
143 /// \return word shifted out
144 /// \details ShiftWordsLeftByBits shifts the word array left by
145 /// shiftBits. ShiftWordsLeftByBits shifts bits out on the left;
146 /// it does not extend the array.
147 /// \note shiftBits must be less than WORD_BITS.
148 /// \since Crypto++ 1.0
149 inline word ShiftWordsLeftByBits(word *r, size_t n, unsigned int shiftBits)
150 {
151 CRYPTOPP_ASSERT (shiftBits<WORD_BITS);
152 word u, carry=0;
153 if (shiftBits)
154 for (size_t i=0; i<n; i++)
155 {
156 u = r[i];
157 r[i] = (u << shiftBits) | carry;
158 carry = u >> (WORD_BITS-shiftBits);
159 }
160 return carry;
161 }
162
163 /// \brief Right shift word array
164 /// \param r word array
165 /// \param n size of the word array, in elements
166 /// \param shiftBits number of bits to shift
167 /// \return word shifted out
168 /// \details ShiftWordsRightByBits shifts the word array shight by
169 /// shiftBits. ShiftWordsRightByBits shifts bits out on the right.
170 /// \note shiftBits must be less than WORD_BITS.
171 /// \since Crypto++ 1.0
172 inline word ShiftWordsRightByBits(word *r, size_t n, unsigned int shiftBits)
173 {
174 CRYPTOPP_ASSERT (shiftBits<WORD_BITS);
175 word u, carry=0;
176 if (shiftBits)
177 for (size_t i=n; i>0; i--)
178 {
179 u = r[i-1];
180 r[i-1] = (u >> shiftBits) | carry;
181 carry = u << (WORD_BITS-shiftBits);
182 }
183 return carry;
184 }
185
186 /// \brief Left shift word array
187 /// \param r word array
188 /// \param n size of the word array, in elements
189 /// \param shiftWords number of words to shift
190 /// \details ShiftWordsLeftByWords shifts the word array left by
191 /// shiftWords. ShiftWordsLeftByWords shifts bits out on the left;
192 /// it does not extend the array.
193 /// \since Crypto++ 1.0
194 inline void ShiftWordsLeftByWords(word *r, size_t n, size_t shiftWords)
195 {
196 shiftWords = STDMIN(shiftWords, n);
197 if (shiftWords)
198 {
199 for (size_t i=n-1; i>=shiftWords; i--)
200 r[i] = r[i-shiftWords];
201 SetWords(r, 0, shiftWords);
202 }
203 }
204
205 /// \brief Right shift word array
206 /// \param r word array
207 /// \param n size of the word array, in elements
208 /// \param shiftWords number of words to shift
209 /// \details ShiftWordsRightByWords shifts the word array right by
210 /// shiftWords. ShiftWordsRightByWords shifts bits out on the right.
211 /// \since Crypto++ 1.0
212 inline void ShiftWordsRightByWords(word *r, size_t n, size_t shiftWords)
213 {
214 shiftWords = STDMIN(shiftWords, n);
215 if (shiftWords)
216 {
217 for (size_t i=0; i+shiftWords<n; i++)
218 r[i] = r[i+shiftWords];
219 SetWords(r+n-shiftWords, 0, shiftWords);
220 }
221 }
222
223 NAMESPACE_END
224
225 #endif
ShiftWordsRightByWords
void ShiftWordsRightByWords(word *r, size_t n, size_t shiftWords)
Right shift word array.
Definition: words.h:212
CRYPTOPP_ASSERT
#define CRYPTOPP_ASSERT(exp)
Debugging and diagnostic assertion.
Definition: trap.h:68
CopyWords
void CopyWords(word *r, const word *a, size_t n)
Copy word array.
Definition: words.h:48
WORD_BITS
const unsigned int WORD_BITS
Size of a platform word in bits.
Definition: config_int.h:249
misc.h
Utility functions for the Crypto++ library.
STDMIN
const T & STDMIN(const T &a, const T &b)
Replacement function for std::min.
Definition: misc.h:635
word
word64 word
Full word used for multiprecision integer arithmetic.
Definition: config_int.h:182
ShiftWordsLeftByWords
void ShiftWordsLeftByWords(word *r, size_t n, size_t shiftWords)
Left shift word array.
Definition: words.h:194
WORD_SIZE
const unsigned int WORD_SIZE
Size of a platform word in bytes.
Definition: config_int.h:245
AndWords
void AndWords(word *r, const word *a, const word *b, size_t n)
AND word arrays.
Definition: words.h:93
CountWords
size_t CountWords(const word *x, size_t n)
Count the number of words.
Definition: words.h:21
OrWords
void OrWords(word *r, const word *a, const word *b, size_t n)
OR word arrays.
Definition: words.h:120
ShiftWordsLeftByBits
word ShiftWordsLeftByBits(word *r, size_t n, unsigned int shiftBits)
Left shift word array.
Definition: words.h:149
ShiftWordsRightByBits
word ShiftWordsRightByBits(word *r, size_t n, unsigned int shiftBits)
Right shift word array.
Definition: words.h:172
CryptoPP
Crypto++ library namespace.
config.h
Library configuration file.
SetWords
void SetWords(word *r, word a, size_t n)
Set the value of words.
Definition: words.h:35
memcpy_s
void memcpy_s(void *dest, size_t sizeInBytes, const void *src, size_t count)
Bounds checking replacement for memcpy()
Definition: misc.h:506
XorWords
void XorWords(word *r, const word *a, const word *b, size_t n)
XOR word arrays.
Definition: words.h:66