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
|
/*
* Fused and Important MP Algorithms
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/numthry.h>
#include <botan/internal/mp_core.h>
#include <botan/internal/rounding.h>
#include <algorithm>
namespace Botan {
/*
* Square a BigInt
*/
BigInt square(const BigInt& x)
{
const size_t x_sw = x.sig_words();
BigInt z(BigInt::Positive, round_up(2*x_sw, 16));
secure_vector<word> workspace(z.size());
bigint_sqr(z.mutable_data(), z.size(),
workspace.data(),
x.data(), x.size(), x_sw);
return z;
}
/*
* Multiply-Add Operation
*/
BigInt mul_add(const BigInt& a, const BigInt& b, const BigInt& c)
{
if(c.is_negative() || c.is_zero())
throw Invalid_Argument("mul_add: Third argument must be > 0");
BigInt::Sign sign = BigInt::Positive;
if(a.sign() != b.sign())
sign = BigInt::Negative;
const size_t a_sw = a.sig_words();
const size_t b_sw = b.sig_words();
const size_t c_sw = c.sig_words();
BigInt r(sign, std::max(a.size() + b.size(), c_sw) + 1);
secure_vector<word> workspace(r.size());
bigint_mul(r.mutable_data(), r.size(),
workspace.data(),
a.data(), a.size(), a_sw,
b.data(), b.size(), b_sw);
const size_t r_size = std::max(r.sig_words(), c_sw);
bigint_add2(r.mutable_data(), r_size, c.data(), c_sw);
return r;
}
/*
* Subtract-Multiply Operation
*/
BigInt sub_mul(const BigInt& a, const BigInt& b, const BigInt& c)
{
if(a.is_negative() || b.is_negative())
throw Invalid_Argument("sub_mul: First two arguments must be >= 0");
BigInt r = a;
r -= b;
r *= c;
return r;
}
}
|
