#include #ifdef BN_MP_2EXPT_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://math.libtomcrypt.com */ /* computes a = 2**b * * Simple algorithm which zeroes the int, grows it then just sets one bit * as required. */ int mp_2expt (mp_int * a, int b) { int res; /* zero a as per default */ mp_zero (a); /* grow a to accomodate the single bit */ if ((res = mp_grow (a, b / DIGIT_BIT + 1)) != MP_OKAY) { return res; } /* set the used count of where the bit will go */ a->used = b / DIGIT_BIT + 1; /* put the single bit in its place */ a->dp[b / DIGIT_BIT] = ((mp_digit)1) << (b % DIGIT_BIT); return MP_OKAY; } #endif /* $Source: /root/tcl/repos-to-convert/tcl/libtommath/bn_mp_2expt.c,v $ */ /* $Revision: 1.1.1.3 $ */ /* $Date: 2006/12/01 00:08:11 $ */