diff options
Diffstat (limited to 'libtommath/bn_mp_rshd.c')
| -rw-r--r-- | libtommath/bn_mp_rshd.c | 107 |
1 files changed, 43 insertions, 64 deletions
diff --git a/libtommath/bn_mp_rshd.c b/libtommath/bn_mp_rshd.c index 4b598de..bb8743e 100644 --- a/libtommath/bn_mp_rshd.c +++ b/libtommath/bn_mp_rshd.c @@ -1,72 +1,51 @@ -#include <tommath_private.h> +#include "tommath_private.h" #ifdef BN_MP_RSHD_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, tstdenis82@gmail.com, http://libtom.org - */ +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ /* shift right a certain amount of digits */ -void mp_rshd (mp_int * a, int b) +void mp_rshd(mp_int *a, int b) { - int x; - - /* if b <= 0 then ignore it */ - if (b <= 0) { - return; - } - - /* if b > used then simply zero it and return */ - if (a->used <= b) { - mp_zero (a); - return; - } - - { - mp_digit *bottom, *top; - - /* shift the digits down */ - - /* bottom */ - bottom = a->dp; - - /* top [offset into digits] */ - top = a->dp + b; - - /* this is implemented as a sliding window where - * the window is b-digits long and digits from - * the top of the window are copied to the bottom - * - * e.g. - - b-2 | b-1 | b0 | b1 | b2 | ... | bb | ----> - /\ | ----> - \-------------------/ ----> - */ - for (x = 0; x < (a->used - b); x++) { + int x; + mp_digit *bottom, *top; + + /* if b <= 0 then ignore it */ + if (b <= 0) { + return; + } + + /* if b > used then simply zero it and return */ + if (a->used <= b) { + mp_zero(a); + return; + } + + /* shift the digits down */ + + /* bottom */ + bottom = a->dp; + + /* top [offset into digits] */ + top = a->dp + b; + + /* this is implemented as a sliding window where + * the window is b-digits long and digits from + * the top of the window are copied to the bottom + * + * e.g. + + b-2 | b-1 | b0 | b1 | b2 | ... | bb | ----> + /\ | ----> + \-------------------/ ----> + */ + for (x = 0; x < (a->used - b); x++) { *bottom++ = *top++; - } + } - /* zero the top digits */ - for (; x < a->used; x++) { - *bottom++ = 0; - } - } - - /* remove excess digits */ - a->used -= b; + /* zero the top digits */ + MP_ZERO_DIGITS(bottom, a->used - x); + + /* remove excess digits */ + a->used -= b; } #endif - -/* ref: $Format:%D$ */ -/* git commit: $Format:%H$ */ -/* commit time: $Format:%ai$ */ |