From 8daa83a594a2e98f39d764422bfbdbc62c9efd44 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 19:20:00 +0200 Subject: Adding upstream version 2:4.20.0+dfsg. Signed-off-by: Daniel Baumann --- .../heimdal/lib/hcrypto/libtommath/bn_mp_sub.c | 40 ++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 third_party/heimdal/lib/hcrypto/libtommath/bn_mp_sub.c (limited to 'third_party/heimdal/lib/hcrypto/libtommath/bn_mp_sub.c') diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_sub.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_sub.c new file mode 100644 index 0000000..c1ea39e --- /dev/null +++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_sub.c @@ -0,0 +1,40 @@ +#include "tommath_private.h" +#ifdef BN_MP_SUB_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +/* high level subtraction (handles signs) */ +mp_err mp_sub(const mp_int *a, const mp_int *b, mp_int *c) +{ + mp_sign sa = a->sign, sb = b->sign; + mp_err err; + + if (sa != sb) { + /* subtract a negative from a positive, OR */ + /* subtract a positive from a negative. */ + /* In either case, ADD their magnitudes, */ + /* and use the sign of the first number. */ + c->sign = sa; + err = s_mp_add(a, b, c); + } else { + /* subtract a positive from a positive, OR */ + /* subtract a negative from a negative. */ + /* First, take the difference between their */ + /* magnitudes, then... */ + if (mp_cmp_mag(a, b) != MP_LT) { + /* Copy the sign from the first */ + c->sign = sa; + /* The first has a larger or equal magnitude */ + err = s_mp_sub(a, b, c); + } else { + /* The result has the *opposite* sign from */ + /* the first number. */ + c->sign = (sa == MP_ZPOS) ? MP_NEG : MP_ZPOS; + /* The second has a larger magnitude */ + err = s_mp_sub(b, a, c); + } + } + return err; +} + +#endif -- cgit v1.2.3