Mercurial > dropbear
view bn_mp_get_int.c @ 1:22d5cf7d4b1a libtommath
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Mon, 31 May 2004 18:23:46 +0000 |
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children | d29b64170cf0 |
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/* 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, [email protected], http://math.libtomcrypt.org */ #include <tommath.h> /* get the lower 32-bits of an mp_int */ unsigned long mp_get_int(mp_int * a) { int i; unsigned long 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; }