mirror of
http://galexander.org/git/simplesshd.git
synced 2024-12-29 09:28:07 +00:00
80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
#include <tommath.h>
|
|
#ifdef BN_MP_MUL_D_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
|
|
*/
|
|
|
|
/* multiply by a digit */
|
|
int
|
|
mp_mul_d (mp_int * a, mp_digit b, mp_int * c)
|
|
{
|
|
mp_digit u, *tmpa, *tmpc;
|
|
mp_word r;
|
|
int ix, res, olduse;
|
|
|
|
/* make sure c is big enough to hold a*b */
|
|
if (c->alloc < a->used + 1) {
|
|
if ((res = mp_grow (c, a->used + 1)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
}
|
|
|
|
/* get the original destinations used count */
|
|
olduse = c->used;
|
|
|
|
/* set the sign */
|
|
c->sign = a->sign;
|
|
|
|
/* alias for a->dp [source] */
|
|
tmpa = a->dp;
|
|
|
|
/* alias for c->dp [dest] */
|
|
tmpc = c->dp;
|
|
|
|
/* zero carry */
|
|
u = 0;
|
|
|
|
/* compute columns */
|
|
for (ix = 0; ix < a->used; ix++) {
|
|
/* compute product and carry sum for this term */
|
|
r = ((mp_word) u) + ((mp_word)*tmpa++) * ((mp_word)b);
|
|
|
|
/* mask off higher bits to get a single digit */
|
|
*tmpc++ = (mp_digit) (r & ((mp_word) MP_MASK));
|
|
|
|
/* send carry into next iteration */
|
|
u = (mp_digit) (r >> ((mp_word) DIGIT_BIT));
|
|
}
|
|
|
|
/* store final carry [if any] and increment ix offset */
|
|
*tmpc++ = u;
|
|
++ix;
|
|
|
|
/* now zero digits above the top */
|
|
while (ix++ < olduse) {
|
|
*tmpc++ = 0;
|
|
}
|
|
|
|
/* set used count */
|
|
c->used = a->used + 1;
|
|
mp_clamp(c);
|
|
|
|
return MP_OKAY;
|
|
}
|
|
#endif
|
|
|
|
/* $Source: /cvs/libtom/libtommath/bn_mp_mul_d.c,v $ */
|
|
/* $Revision: 1.3 $ */
|
|
/* $Date: 2006/03/31 14:18:44 $ */
|