## File: bn_mp_mod_2d.c

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libtommath 1.1.0-3
 `123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051` ``````#include "tommath_private.h" #ifdef BN_MP_MOD_2D_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * * LibTomMath is a library that provides multiple-precision * integer arithmetic as well as number theoretic functionality. * * The library was designed directly after the MPI library by * Michael Fromberger but has been written from scratch with * additional optimizations in place. * * SPDX-License-Identifier: Unlicense */ /* calc a value mod 2**b */ int mp_mod_2d(const mp_int *a, int b, mp_int *c) { int x, res; /* if b is <= 0 then zero the int */ if (b <= 0) { mp_zero(c); return MP_OKAY; } /* if the modulus is larger than the value than return */ if (b >= (a->used * DIGIT_BIT)) { res = mp_copy(a, c); return res; } /* copy */ if ((res = mp_copy(a, c)) != MP_OKAY) { return res; } /* zero digits above the last digit of the modulus */ for (x = (b / DIGIT_BIT) + (((b % DIGIT_BIT) == 0) ? 0 : 1); x < c->used; x++) { c->dp[x] = 0; } /* clear the digit that is not completely outside/inside the modulus */ c->dp[b / DIGIT_BIT] &= ((mp_digit)1 << (mp_digit)(b % DIGIT_BIT)) - (mp_digit)1; mp_clamp(c); return MP_OKAY; } #endif /* ref: HEAD -> master, tag: v1.1.0 */ /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ /* commit time: 2019-01-28 20:32:32 +0100 */ ``````