Mercurial > dropbear
annotate bn_mp_mod_2d.c @ 203:e109027b9edf libtommath LTM_DB_0.46 LTM_DB_0.47
Don't remove ~ files on make clean (and find -type was wrong anyway)
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Wed, 11 May 2005 16:27:28 +0000 |
| parents | d8254fc979e9 |
| children |
| rev | line source |
|---|---|
| 142 | 1 #include <tommath.h> |
| 2 #ifdef BN_MP_MOD_2D_C | |
| 2 | 3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
| 4 * | |
| 5 * LibTomMath is a library that provides multiple-precision | |
| 6 * integer arithmetic as well as number theoretic functionality. | |
| 7 * | |
| 8 * The library was designed directly after the MPI library by | |
| 9 * Michael Fromberger but has been written from scratch with | |
| 10 * additional optimizations in place. | |
| 11 * | |
| 12 * The library is free for all purposes without any express | |
| 13 * guarantee it works. | |
| 14 * | |
| 15 * Tom St Denis, [email protected], http://math.libtomcrypt.org | |
| 16 */ | |
| 17 | |
| 18 /* calc a value mod 2**b */ | |
| 19 int | |
| 20 mp_mod_2d (mp_int * a, int b, mp_int * c) | |
| 21 { | |
| 22 int x, res; | |
| 23 | |
| 24 /* if b is <= 0 then zero the int */ | |
| 25 if (b <= 0) { | |
| 26 mp_zero (c); | |
| 27 return MP_OKAY; | |
| 28 } | |
| 29 | |
| 30 /* if the modulus is larger than the value than return */ | |
|
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d8254fc979e9
Initial import of libtommath 0.35
Matt Johnston <matt@ucc.asn.au>
parents:
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31 if (b >= (int) (a->used * DIGIT_BIT)) { |
| 2 | 32 res = mp_copy (a, c); |
| 33 return res; | |
| 34 } | |
| 35 | |
| 36 /* copy */ | |
| 37 if ((res = mp_copy (a, c)) != MP_OKAY) { | |
| 38 return res; | |
| 39 } | |
| 40 | |
| 41 /* zero digits above the last digit of the modulus */ | |
| 42 for (x = (b / DIGIT_BIT) + ((b % DIGIT_BIT) == 0 ? 0 : 1); x < c->used; x++) { | |
| 43 c->dp[x] = 0; | |
| 44 } | |
| 45 /* clear the digit that is not completely outside/inside the modulus */ | |
| 46 c->dp[b / DIGIT_BIT] &= | |
| 47 (mp_digit) ((((mp_digit) 1) << (((mp_digit) b) % DIGIT_BIT)) - ((mp_digit) 1)); | |
| 48 mp_clamp (c); | |
| 49 return MP_OKAY; | |
| 50 } | |
| 142 | 51 #endif |