Mercurial > dropbear
diff libtommath/bn_mp_decr.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 | |
| children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libtommath/bn_mp_decr.c Tue May 26 17:36:47 2020 +0200 @@ -0,0 +1,34 @@ +#include "tommath_private.h" +#ifdef BN_MP_DECR_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +/* Decrement "a" by one like "a--". Changes input! */ +mp_err mp_decr(mp_int *a) +{ + if (MP_IS_ZERO(a)) { + mp_set(a,1uL); + a->sign = MP_NEG; + return MP_OKAY; + } else if (a->sign == MP_NEG) { + mp_err err; + a->sign = MP_ZPOS; + if ((err = mp_incr(a)) != MP_OKAY) { + return err; + } + /* There is no -0 in LTM */ + if (!MP_IS_ZERO(a)) { + a->sign = MP_NEG; + } + return MP_OKAY; + } else if (a->dp[0] > 1uL) { + a->dp[0]--; + if (a->dp[0] == 0u) { + mp_zero(a); + } + return MP_OKAY; + } else { + return mp_sub_d(a, 1uL,a); + } +} +#endif