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comparison libtommath/bn_mp_lshd.c @ 1436:60fc6476e044

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Update to libtommath v1.0
author Matt Johnston <matt@ucc.asn.au>
date Sat, 24 Jun 2017 22:37:14 +0800
parents 5ff8218bcee9
children 8bba51a55704
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1435:f849a5ca2efc 1436:60fc6476e044
1 #include <tommath.h> 1 #include <tommath_private.h>
2 #ifdef BN_MP_LSHD_C 2 #ifdef BN_MP_LSHD_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.
10 * additional optimizations in place. 10 * additional optimizations in place.
11 * 11 *
12 * The library is free for all purposes without any express 12 * The library is free for all purposes without any express
13 * guarantee it works. 13 * guarantee it works.
14 * 14 *
15 * Tom St Denis, [email protected], http://math.libtomcrypt.com 15 * Tom St Denis, [email protected], http://libtom.org
16 */ 16 */
17 17
18 /* shift left a certain amount of digits */ 18 /* shift left a certain amount of digits */
19 int mp_lshd (mp_int * a, int b) 19 int mp_lshd (mp_int * a, int b)
20 { 20 {
24 if (b <= 0) { 24 if (b <= 0) {
25 return MP_OKAY; 25 return MP_OKAY;
26 } 26 }
27 27
28 /* grow to fit the new digits */ 28 /* grow to fit the new digits */
29 if (a->alloc < a->used + b) { 29 if (a->alloc < (a->used + b)) {
30 if ((res = mp_grow (a, a->used + b)) != MP_OKAY) { 30 if ((res = mp_grow (a, a->used + b)) != MP_OKAY) {
31 return res; 31 return res;
32 } 32 }
33 } 33 }
34 34
35 { 35 {
36 register mp_digit *top, *bottom; 36 mp_digit *top, *bottom;
37 37
38 /* increment the used by the shift amount then copy upwards */ 38 /* increment the used by the shift amount then copy upwards */
39 a->used += b; 39 a->used += b;
40 40
41 /* top */ 41 /* top */
42 top = a->dp + a->used - 1; 42 top = a->dp + a->used - 1;
43 43
44 /* base */ 44 /* base */
45 bottom = a->dp + a->used - 1 - b; 45 bottom = (a->dp + a->used - 1) - b;
46 46
47 /* much like mp_rshd this is implemented using a sliding window 47 /* much like mp_rshd this is implemented using a sliding window
48 * except the window goes the otherway around. Copying from 48 * except the window goes the otherway around. Copying from
49 * the bottom to the top. see bn_mp_rshd.c for more info. 49 * the bottom to the top. see bn_mp_rshd.c for more info.
50 */ 50 */
60 } 60 }
61 return MP_OKAY; 61 return MP_OKAY;
62 } 62 }
63 #endif 63 #endif
64 64
65 /* $Source: /cvs/libtom/libtommath/bn_mp_lshd.c,v $ */ 65 /* $Source$ */
66 /* $Revision: 1.3 $ */ 66 /* $Revision$ */
67 /* $Date: 2006/03/31 14:18:44 $ */ 67 /* $Date$ */