Mercurial > dropbear
view libtommath/bn_mp_lshd.c @ 1032:0da8ba489c23 fastopen
Move generic network routines to netio.c
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Fri, 20 Feb 2015 23:16:38 +0800 |
parents | 5ff8218bcee9 |
children | 60fc6476e044 |
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#include <tommath.h> #ifdef BN_MP_LSHD_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, [email protected], http://math.libtomcrypt.com */ /* shift left a certain amount of digits */ int mp_lshd (mp_int * a, int b) { int x, res; /* if its less than zero return */ if (b <= 0) { return MP_OKAY; } /* grow to fit the new digits */ if (a->alloc < a->used + b) { if ((res = mp_grow (a, a->used + b)) != MP_OKAY) { return res; } } { register mp_digit *top, *bottom; /* increment the used by the shift amount then copy upwards */ a->used += b; /* top */ top = a->dp + a->used - 1; /* base */ bottom = a->dp + a->used - 1 - b; /* much like mp_rshd this is implemented using a sliding window * except the window goes the otherway around. Copying from * the bottom to the top. see bn_mp_rshd.c for more info. */ for (x = a->used - 1; x >= b; x--) { *top-- = *bottom--; } /* zero the lower digits */ top = a->dp; for (x = 0; x < b; x++) { *top++ = 0; } } return MP_OKAY; } #endif /* $Source: /cvs/libtom/libtommath/bn_mp_lshd.c,v $ */ /* $Revision: 1.3 $ */ /* $Date: 2006/03/31 14:18:44 $ */