1 files changed, 52 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_mul.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_mul.c
new file mode 100644
index 0000000..561913a
--- /dev/null
+++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_mul.c
@@ -0,0 +1,52 @@
+#include "tommath_private.h"
+#ifdef BN_MP_MUL_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
+
+/* high level multiplication (handles sign) */
+mp_err mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
+{
+   mp_err err;
+   int min_len = MP_MIN(a->used, b->used),
+       max_len = MP_MAX(a->used, b->used),
+       digs = a->used + b->used + 1;
+   mp_sign neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+
+   if (MP_HAS(S_MP_BALANCE_MUL) &&
+       /* Check sizes. The smaller one needs to be larger than the Karatsuba cut-off.
+        * The bigger one needs to be at least about one MP_KARATSUBA_MUL_CUTOFF bigger
+        * to make some sense, but it depends on architecture, OS, position of the
+        * stars... so YMMV.
+        * Using it to cut the input into slices small enough for fast_s_mp_mul_digs
+        * was actually slower on the author's machine, but YMMV.
+        */
+       (min_len >= MP_KARATSUBA_MUL_CUTOFF) &&
+       ((max_len / 2) >= MP_KARATSUBA_MUL_CUTOFF) &&
+       /* Not much effect was observed below a ratio of 1:2, but again: YMMV. */
+       (max_len >= (2 * min_len))) {
+      err = s_mp_balance_mul(a,b,c);
+   } else if (MP_HAS(S_MP_TOOM_MUL) &&
+              (min_len >= MP_TOOM_MUL_CUTOFF)) {
+      err = s_mp_toom_mul(a, b, c);
+   } else if (MP_HAS(S_MP_KARATSUBA_MUL) &&
+              (min_len >= MP_KARATSUBA_MUL_CUTOFF)) {
+      err = s_mp_karatsuba_mul(a, b, c);
+   } else if (MP_HAS(S_MP_MUL_DIGS_FAST) &&
+              /* can we use the fast multiplier?
+               *
+               * The fast multiplier can be used if the output will
+               * have less than MP_WARRAY digits and the number of
+               * digits won't affect carry propagation
+               */
+              (digs < MP_WARRAY) &&
+              (min_len <= MP_MAXFAST)) {
+      err = s_mp_mul_digs_fast(a, b, c, digs);
+   } else if (MP_HAS(S_MP_MUL_DIGS)) {
+      err = s_mp_mul_digs(a, b, c, digs);
+   } else {
+      err = MP_VAL;
+   }
+   c->sign = (c->used > 0) ? neg : MP_ZPOS;
+   return err;
+}
+#endif