Initial Mangos Three Commit

dep/tomlib/Math/src/bn_mp_mul.c

@@ -0,0 +1,86 @@
+#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) */
+int mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
+{
+   int     res, neg;
+#ifdef BN_S_MP_BALANCE_MUL_C
+   int len_b, len_a;
+#endif
+   neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+#ifdef BN_S_MP_BALANCE_MUL_C
+   len_a = a->used;
+   len_b = b->used;
+
+   if (len_a == len_b) {
+      goto GO_ON;
+   }
+   /*
+    * Check sizes. The smaller one needs to be larger than the Karatsuba cut-off.
+    * The bigger one needs to be at least about one 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.
+    */
+   if ((MP_MIN(len_a, len_b) < KARATSUBA_MUL_CUTOFF)
+       || ((MP_MAX(len_a, len_b) / 2) < KARATSUBA_MUL_CUTOFF)) {
+      goto GO_ON;
+   }
+   /*
+    * Not much effect was observed below a ratio of 1:2, but again: YMMV.
+    */
+   if ((MP_MAX(len_a, len_b) /  MP_MIN(len_a, len_b)) < 2) {
+      goto GO_ON;
+   }
+
+   res = s_mp_balance_mul(a,b,c);
+   goto END;
+
+GO_ON:
+#endif
+
+   /* use Toom-Cook? */
+#ifdef BN_S_MP_TOOM_MUL_C
+   if (MP_MIN(a->used, b->used) >= TOOM_MUL_CUTOFF) {
+      res = s_mp_toom_mul(a, b, c);
+   } else
+#endif
+#ifdef BN_S_MP_KARATSUBA_MUL_C
+      /* use Karatsuba? */
+      if (MP_MIN(a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
+         res = s_mp_karatsuba_mul(a, b, c);
+      } else
+#endif
+      {
+         /* 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
+          */
+         int     digs = a->used + b->used + 1;
+
+#ifdef BN_S_MP_MUL_DIGS_FAST_C
+         if ((digs < (int)MP_WARRAY) &&
+             (MP_MIN(a->used, b->used) <=
+              (int)(1u << ((CHAR_BIT * sizeof(mp_word)) - (2u * (size_t)MP_DIGIT_BIT))))) {
+            res = s_mp_mul_digs_fast(a, b, c, digs);
+         } else
+#endif
+         {
+#ifdef BN_S_MP_MUL_DIGS_C
+            res = s_mp_mul_digs(a, b, c, a->used + b->used + 1);
+#else
+            res = MP_VAL;
+#endif
+         }
+      }
+END:
+   c->sign = (c->used > 0) ? neg : MP_ZPOS;
+   return res;
+}
+#endif