blob: 9e11eef7abc122dd202e8a9ce65f34955389f090 [file] [log] [blame]
 #include #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@iahu.ca, http://math.libtomcrypt.org */ /* 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