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view 3rdparty/libtommath/bn_mp_get_int.c @ 0:2cf249471370
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author | Takahiro SHIMIZU <anatofuz@cr.ie.u-ryukyu.ac.jp> |
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date | Tue, 08 May 2018 16:09:12 +0900 |
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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. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, tstdenis82@gmail.com, http://libtom.org */ /* get the lower 32-bits of an mp_int */ unsigned long mp_get_int(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 /* $Source$ */ /* $Revision$ */ /* $Date$ */