From ab6e3fce040f9ad27cbce44e9038a24f15b601c8 Mon Sep 17 00:00:00 2001 From: Matthieu Patou Date: Sun, 15 Aug 2010 18:31:28 +0400 Subject: s4:heimdal: import lorikeet-heimdal-201009250123 (commit 42cabfb5b683dbcb97d583c397b897507689e382) I based this on Matthieu's import of lorikeet-heimdal, and then updated it to this commit. Andrew Bartlett --- .../heimdal/lib/hcrypto/libtommath/bn_mp_div_2d.c | 97 ++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 source4/heimdal/lib/hcrypto/libtommath/bn_mp_div_2d.c (limited to 'source4/heimdal/lib/hcrypto/libtommath/bn_mp_div_2d.c') diff --git a/source4/heimdal/lib/hcrypto/libtommath/bn_mp_div_2d.c b/source4/heimdal/lib/hcrypto/libtommath/bn_mp_div_2d.c new file mode 100644 index 0000000000..4f7fa59e3f --- /dev/null +++ b/source4/heimdal/lib/hcrypto/libtommath/bn_mp_div_2d.c @@ -0,0 +1,97 @@ +#include +#ifdef BN_MP_DIV_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. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtom.org + */ + +/* shift right by a certain bit count (store quotient in c, optional remainder in d) */ +int mp_div_2d (mp_int * a, int b, mp_int * c, mp_int * d) +{ + mp_digit D, r, rr; + int x, res; + mp_int t; + + + /* if the shift count is <= 0 then we do no work */ + if (b <= 0) { + res = mp_copy (a, c); + if (d != NULL) { + mp_zero (d); + } + return res; + } + + if ((res = mp_init (&t)) != MP_OKAY) { + return res; + } + + /* get the remainder */ + if (d != NULL) { + if ((res = mp_mod_2d (a, b, &t)) != MP_OKAY) { + mp_clear (&t); + return res; + } + } + + /* copy */ + if ((res = mp_copy (a, c)) != MP_OKAY) { + mp_clear (&t); + return res; + } + + /* shift by as many digits in the bit count */ + if (b >= (int)DIGIT_BIT) { + mp_rshd (c, b / DIGIT_BIT); + } + + /* shift any bit count < DIGIT_BIT */ + D = (mp_digit) (b % DIGIT_BIT); + if (D != 0) { + register mp_digit *tmpc, mask, shift; + + /* mask */ + mask = (((mp_digit)1) << D) - 1; + + /* shift for lsb */ + shift = DIGIT_BIT - D; + + /* alias */ + tmpc = c->dp + (c->used - 1); + + /* carry */ + r = 0; + for (x = c->used - 1; x >= 0; x--) { + /* get the lower bits of this word in a temp */ + rr = *tmpc & mask; + + /* shift the current word and mix in the carry bits from the previous word */ + *tmpc = (*tmpc >> D) | (r << shift); + --tmpc; + + /* set the carry to the carry bits of the current word found above */ + r = rr; + } + } + mp_clamp (c); + if (d != NULL) { + mp_exch (&t, d); + } + mp_clear (&t); + return MP_OKAY; +} +#endif + +/* $Source: /cvs/libtom/libtommath/bn_mp_div_2d.c,v $ */ +/* $Revision: 1.4 $ */ +/* $Date: 2006/12/28 01:25:13 $ */ -- cgit