Mercurial > dropbear
view libtommath/bn_mp_lshd.c @ 1692:1051e4eea25a
Update LibTomMath to 1.2.0 (#84)
* update C files
* update other files
* update headers
* update makefiles
* remove mp_set/get_double()
* use ltm 1.2.0 API
* update ltm_desc
* use bundled tommath if system-tommath is too old
* XMALLOC etc. were changed to MP_MALLOC etc.
author | Steffen Jaeckel <s@jaeckel.eu> |
---|---|
date | Tue, 26 May 2020 17:36:47 +0200 |
parents | f52919ffd3b1 |
children |
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#include "tommath_private.h" #ifdef BN_MP_LSHD_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* shift left a certain amount of digits */ mp_err mp_lshd(mp_int *a, int b) { int x; mp_err err; mp_digit *top, *bottom; /* if its less than zero return */ if (b <= 0) { return MP_OKAY; } /* no need to shift 0 around */ if (MP_IS_ZERO(a)) { return MP_OKAY; } /* grow to fit the new digits */ if (a->alloc < (a->used + b)) { if ((err = mp_grow(a, a->used + b)) != MP_OKAY) { return err; } } /* 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 */ MP_ZERO_DIGITS(a->dp, b); return MP_OKAY; } #endif