Mercurial > dropbear
view libtommath/bn_mp_get_int.c @ 1663:c795520269f9
Fallback for key gen without hard link support (#89)
Add a non-atomic fallback for key generation on platforms where link()
is not permitted (such as most stock Android installs) or on filesystems
without hard link support (such as FAT).
author | Matt Robinson <git@nerdoftheherd.com> |
---|---|
date | Sat, 14 Mar 2020 14:37:35 +0000 |
parents | f52919ffd3b1 |
children |
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#include "tommath_private.h" #ifdef BN_MP_GET_INT_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 */ /* get the lower 32-bits of an mp_int */ unsigned long mp_get_int(const mp_int *a) { int i; mp_min_u32 res; if (a->used == 0) { return 0; } /* get number of digits of the lsb we have to read */ i = MIN(a->used, ((((int)sizeof(unsigned long) * CHAR_BIT) + DIGIT_BIT - 1) / DIGIT_BIT)) - 1; /* get most significant digit of result */ res = DIGIT(a, i); while (--i >= 0) { res = (res << DIGIT_BIT) | DIGIT(a, i); } /* force result to 32-bits always so it is consistent on non 32-bit platforms */ return res & 0xFFFFFFFFUL; } #endif /* ref: HEAD -> master, tag: v1.1.0 */ /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ /* commit time: 2019-01-28 20:32:32 +0100 */