Mercurial > dropbear
comparison libtommath/bn_mp_div_2.c @ 1655:f52919ffd3b1
update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
* make key-generation compliant to FIPS 186.4
* fix includes in tommath_class.h
* update fuzzcorpus instead of error-out
* fixup fuzzing make-targets
* update Makefile.in
* apply necessary patches to ltm sources
* clean-up not required ltm files
* update to vanilla ltm 1.1.0
this already only contains the required files
* remove set/get double
author | Steffen Jaeckel <s_jaeckel@gmx.de> |
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date | Mon, 16 Sep 2019 15:50:38 +0200 |
parents | 8bba51a55704 |
children | 1051e4eea25a |
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1654:cc0fc5131c5c | 1655:f52919ffd3b1 |
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1 #include <tommath_private.h> | 1 #include "tommath_private.h" |
2 #ifdef BN_MP_DIV_2_C | 2 #ifdef BN_MP_DIV_2_C |
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis | 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
4 * | 4 * |
5 * LibTomMath is a library that provides multiple-precision | 5 * LibTomMath is a library that provides multiple-precision |
6 * integer arithmetic as well as number theoretic functionality. | 6 * integer arithmetic as well as number theoretic functionality. |
7 * | 7 * |
8 * The library was designed directly after the MPI library by | 8 * The library was designed directly after the MPI library by |
9 * Michael Fromberger but has been written from scratch with | 9 * Michael Fromberger but has been written from scratch with |
10 * additional optimizations in place. | 10 * additional optimizations in place. |
11 * | 11 * |
12 * The library is free for all purposes without any express | 12 * SPDX-License-Identifier: Unlicense |
13 * guarantee it works. | |
14 * | |
15 * Tom St Denis, [email protected], http://libtom.org | |
16 */ | 13 */ |
17 | 14 |
18 /* b = a/2 */ | 15 /* b = a/2 */ |
19 int mp_div_2(mp_int * a, mp_int * b) | 16 int mp_div_2(const mp_int *a, mp_int *b) |
20 { | 17 { |
21 int x, res, oldused; | 18 int x, res, oldused; |
22 | 19 |
23 /* copy */ | 20 /* copy */ |
24 if (b->alloc < a->used) { | 21 if (b->alloc < a->used) { |
25 if ((res = mp_grow (b, a->used)) != MP_OKAY) { | 22 if ((res = mp_grow(b, a->used)) != MP_OKAY) { |
26 return res; | 23 return res; |
27 } | 24 } |
28 } | 25 } |
29 | 26 |
30 oldused = b->used; | 27 oldused = b->used; |
31 b->used = a->used; | 28 b->used = a->used; |
32 { | 29 { |
33 mp_digit r, rr, *tmpa, *tmpb; | 30 mp_digit r, rr, *tmpa, *tmpb; |
34 | 31 |
35 /* source alias */ | 32 /* source alias */ |
36 tmpa = a->dp + b->used - 1; | 33 tmpa = a->dp + b->used - 1; |
37 | 34 |
38 /* dest alias */ | 35 /* dest alias */ |
39 tmpb = b->dp + b->used - 1; | 36 tmpb = b->dp + b->used - 1; |
40 | 37 |
41 /* carry */ | 38 /* carry */ |
42 r = 0; | 39 r = 0; |
43 for (x = b->used - 1; x >= 0; x--) { | 40 for (x = b->used - 1; x >= 0; x--) { |
44 /* get the carry for the next iteration */ | 41 /* get the carry for the next iteration */ |
45 rr = *tmpa & 1; | 42 rr = *tmpa & 1u; |
46 | 43 |
47 /* shift the current digit, add in carry and store */ | 44 /* shift the current digit, add in carry and store */ |
48 *tmpb-- = (*tmpa-- >> 1) | (r << (DIGIT_BIT - 1)); | 45 *tmpb-- = (*tmpa-- >> 1) | (r << (DIGIT_BIT - 1)); |
49 | 46 |
50 /* forward carry to next iteration */ | 47 /* forward carry to next iteration */ |
51 r = rr; | 48 r = rr; |
52 } | 49 } |
53 | 50 |
54 /* zero excess digits */ | 51 /* zero excess digits */ |
55 tmpb = b->dp + b->used; | 52 tmpb = b->dp + b->used; |
56 for (x = b->used; x < oldused; x++) { | 53 for (x = b->used; x < oldused; x++) { |
57 *tmpb++ = 0; | 54 *tmpb++ = 0; |
58 } | 55 } |
59 } | 56 } |
60 b->sign = a->sign; | 57 b->sign = a->sign; |
61 mp_clamp (b); | 58 mp_clamp(b); |
62 return MP_OKAY; | 59 return MP_OKAY; |
63 } | 60 } |
64 #endif | 61 #endif |
65 | 62 |
66 /* ref: $Format:%D$ */ | 63 /* ref: HEAD -> master, tag: v1.1.0 */ |
67 /* git commit: $Format:%H$ */ | 64 /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ |
68 /* commit time: $Format:%ai$ */ | 65 /* commit time: 2019-01-28 20:32:32 +0100 */ |