3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
12 * The library is free for all purposes without any express
15 * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
18 /* shift left a certain amount of digits */
19 int mp_lshd (mp_int * a, int b)
23 /* if its less than zero return */
28 /* grow to fit the new digits */
29 if (a->alloc < a->used + b) {
30 if ((res = mp_grow (a, a->used + b)) != MP_OKAY) {
36 register mp_digit *top, *bottom;
38 /* increment the used by the shift amount then copy upwards */
42 top = a->dp + a->used - 1;
45 bottom = a->dp + a->used - 1 - b;
47 /* much like mp_rshd this is implemented using a sliding window
48 * except the window goes the otherway around. Copying from
49 * the bottom to the top. see bn_mp_rshd.c for more info.
51 for (x = a->used - 1; x >= b; x--) {
55 /* zero the lower digits */
57 for (x = 0; x < b; x++) {