aboutsummaryrefslogtreecommitdiffstats
path: root/src/lib/math/bigint/divide.h
blob: deb6ffdbbdc6fee74a1c2e814a11cead7726b486 (plain)
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
/*
* Division
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_DIVISON_ALGORITHM_H_
#define BOTAN_DIVISON_ALGORITHM_H_

#include <botan/bigint.h>

BOTAN_FUTURE_INTERNAL_HEADER(divide.h)

namespace Botan {

/**
* BigInt Division
* @param x an integer
* @param y a non-zero integer
* @param q will be set to x / y
* @param r will be set to x % y
*/
void BOTAN_PUBLIC_API(2,0) divide(const BigInt& x,
                                  const BigInt& y,
                                  BigInt& q,
                                  BigInt& r);

/**
* BigInt division, const time variant
*
* This runs with control flow independent of the values of x/y.
* Warning: the loop bounds still leak the sizes of x and y.
*
* @param x an integer
* @param y a non-zero integer
* @param q will be set to x / y
* @param r will be set to x % y
*/
void BOTAN_PUBLIC_API(2,9) ct_divide(const BigInt& x,
                                     const BigInt& y,
                                     BigInt& q,
                                     BigInt& r);

/**
* BigInt division, const time variant
*
* This runs with control flow independent of the values of x/y.
* Warning: the loop bounds still leak the sizes of x and y.
*
* @param x an integer
* @param y a non-zero integer
* @return x/y with remainder discarded
*/
inline BigInt ct_divide(const BigInt& x, const BigInt& y)
   {
   BigInt q, r;
   ct_divide(x, y, q, r);
   return q;
   }

/**
* BigInt division, const time variant
*
* This runs with control flow independent of the values of x/y.
* Warning: the loop bounds still leak the sizes of x and y.
*
* @param x an integer
* @param y a non-zero integer
* @param q will be set to x / y
* @param r will be set to x % y
*/
void BOTAN_PUBLIC_API(2,9) ct_divide_u8(const BigInt& x,
                                        uint8_t y,
                                        BigInt& q,
                                        uint8_t& r);

/**
* BigInt modulo, const time variant
*
* Using this function is (slightly) cheaper than calling ct_divide and
* using only the remainder.
*
* @param x a non-negative integer
* @param modulo a positive integer
* @return result x % modulo
*/
BigInt BOTAN_PUBLIC_API(2,9) ct_modulo(const BigInt& x,
                                       const BigInt& modulo);

}

#endif