merge from main

--HG--
branch : fuzz

1 files changed, 45 insertions, 60 deletions

diff --git a/libtommath/bn_mp_mul.c b/libtommath/bn_mp_mul.c
index cc3b9c8..561913a 100644
--- a/libtommath/bn_mp_mul.c
+++ b/libtommath/bn_mp_mul.c
@@ -1,67 +1,52 @@
-#include <tommath_private.h>
+#include "tommath_private.h"
 #ifdef BN_MP_MUL_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 */
 
 /* high level multiplication (handles sign) */
-int mp_mul (mp_int * a, mp_int * b, mp_int * c)
+mp_err mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
-  int     res, neg;
-  neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+   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;
 
-  /* use Toom-Cook? */
-#ifdef BN_MP_TOOM_MUL_C
-  if (MIN (a->used, b->used) >= TOOM_MUL_CUTOFF) {
-    res = mp_toom_mul(a, b, c);
-  } else 
-#endif
-#ifdef BN_MP_KARATSUBA_MUL_C
-  /* use Karatsuba? */
-  if (MIN (a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
-    res = 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_FAST_S_MP_MUL_DIGS_C
-    if ((digs < MP_WARRAY) &&
-        (MIN(a->used, b->used) <= 
-         (1 << ((CHAR_BIT * sizeof(mp_word)) - (2 * DIGIT_BIT))))) {
-      res = fast_s_mp_mul_digs (a, b, c, digs);
-    } else 
-#endif
-    {
-#ifdef BN_S_MP_MUL_DIGS_C
-      res = s_mp_mul (a, b, c); /* uses s_mp_mul_digs */
-#else
-      res = MP_VAL;
-#endif
-    }
-  }
-  c->sign = (c->used > 0) ? neg : MP_ZPOS;
-  return res;
+   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
-
-/* ref:         $Format:%D$ */
-/* git commit:  $Format:%H$ */
-/* commit time: $Format:%ai$ */