1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
/*
* BigInt Assignment Operators
* (C) 1999-2007 Jack Lloyd
* 2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/bigint.h>
#include <botan/internal/mp_core.h>
#include <botan/internal/bit_ops.h>
#include <algorithm>
namespace Botan {
/*
* Addition Operator
*/
BigInt& BigInt::operator+=(const BigInt& y)
{
const size_t x_sw = sig_words(), y_sw = y.sig_words();
const size_t reg_size = std::max(x_sw, y_sw) + 1;
if(m_reg.size() < reg_size)
grow_to(reg_size);
if(sign() == y.sign())
bigint_add2(mutable_data(), reg_size - 1, y.data(), y_sw);
else
{
int32_t relative_size = bigint_cmp(data(), x_sw, y.data(), y_sw);
if(relative_size < 0)
{
secure_vector<word> z(reg_size - 1);
bigint_sub3(z.data(), y.data(), reg_size - 1, data(), x_sw);
std::swap(m_reg, z);
set_sign(y.sign());
}
else if(relative_size == 0)
{
zeroise(m_reg);
set_sign(Positive);
}
else if(relative_size > 0)
bigint_sub2(mutable_data(), x_sw, y.data(), y_sw);
}
return (*this);
}
/*
* Subtraction Operator
*/
BigInt& BigInt::operator-=(const BigInt& y)
{
const size_t x_sw = sig_words(), y_sw = y.sig_words();
int32_t relative_size = bigint_cmp(data(), x_sw, y.data(), y_sw);
const size_t reg_size = std::max(x_sw, y_sw) + 1;
grow_to(reg_size);
if(relative_size < 0)
{
if(sign() == y.sign())
bigint_sub2_rev(mutable_data(), y.data(), y_sw);
else
bigint_add2(mutable_data(), reg_size - 1, y.data(), y_sw);
set_sign(y.reverse_sign());
}
else if(relative_size == 0)
{
if(sign() == y.sign())
{
clear();
set_sign(Positive);
}
else
bigint_shl1(mutable_data(), x_sw, 0, 1);
}
else if(relative_size > 0)
{
if(sign() == y.sign())
bigint_sub2(mutable_data(), x_sw, y.data(), y_sw);
else
bigint_add2(mutable_data(), reg_size - 1, y.data(), y_sw);
}
return (*this);
}
/*
* Multiplication Operator
*/
BigInt& BigInt::operator*=(const BigInt& y)
{
const size_t x_sw = sig_words(), y_sw = y.sig_words();
set_sign((sign() == y.sign()) ? Positive : Negative);
if(x_sw == 0 || y_sw == 0)
{
clear();
set_sign(Positive);
}
else if(x_sw == 1 && y_sw)
{
grow_to(y_sw + 2);
bigint_linmul3(mutable_data(), y.data(), y_sw, word_at(0));
}
else if(y_sw == 1 && x_sw)
{
grow_to(x_sw + 2);
bigint_linmul2(mutable_data(), x_sw, y.word_at(0));
}
else
{
grow_to(size() + y.size());
secure_vector<word> workspace(size());
bigint_mul(*this, BigInt(*this), y, workspace.data(), workspace.size());
}
return (*this);
}
/*
* Division Operator
*/
BigInt& BigInt::operator/=(const BigInt& y)
{
if(y.sig_words() == 1 && is_power_of_2(y.word_at(0)))
(*this) >>= (y.bits() - 1);
else
(*this) = (*this) / y;
return (*this);
}
/*
* Modulo Operator
*/
BigInt& BigInt::operator%=(const BigInt& mod)
{
return (*this = (*this) % mod);
}
/*
* Modulo Operator
*/
word BigInt::operator%=(word mod)
{
if(mod == 0)
throw BigInt::DivideByZero();
if(is_power_of_2(mod))
{
word result = (word_at(0) & (mod - 1));
clear();
grow_to(2);
m_reg[0] = result;
return result;
}
word remainder = 0;
for(size_t j = sig_words(); j > 0; --j)
remainder = bigint_modop(remainder, word_at(j-1), mod);
clear();
grow_to(2);
if(remainder && sign() == BigInt::Negative)
m_reg[0] = mod - remainder;
else
m_reg[0] = remainder;
set_sign(BigInt::Positive);
return word_at(0);
}
/*
* Left Shift Operator
*/
BigInt& BigInt::operator<<=(size_t shift)
{
if(shift)
{
const size_t shift_words = shift / MP_WORD_BITS,
shift_bits = shift % MP_WORD_BITS,
words = sig_words();
grow_to(words + shift_words + (shift_bits ? 1 : 0));
bigint_shl1(mutable_data(), words, shift_words, shift_bits);
}
return (*this);
}
/*
* Right Shift Operator
*/
BigInt& BigInt::operator>>=(size_t shift)
{
if(shift)
{
const size_t shift_words = shift / MP_WORD_BITS,
shift_bits = shift % MP_WORD_BITS;
bigint_shr1(mutable_data(), sig_words(), shift_words, shift_bits);
if(is_zero())
set_sign(Positive);
}
return (*this);
}
}
|
