Revert "balancing multiplication like that in Ruby 1.9"

This reverts commit e68439aae10d003250afa6c1f57025bfee5f82ed.

Conflicts:
	bn_mp_balance_mul.c
	makefile

bn_mp_balance_mul.c

@@ -1,101 +0,0 @@
-#include <tommath.h>
-#ifdef BN_MP_BALANCE_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, tomstdenis@gmail.com, http://libtom.org
- */
-
-/* c = |a| * |b| using balancing multiplication.
- * If |a| is much less than |b|,
- * we firstly split b into chunks such that length of each one is
- * roughly equal to that of |a|.
- */
-int mp_balance_mul (mp_int * a, mp_int * b, mp_int * c)
-{
-  /* the following algorithm is taken from
-   * Ruby core; namely, function 'bigmul1_balance'
-   * from 'bignum.c'
-   */
-  mp_int t1, t2;
-  long i, an, bn, r, n;
-  int res,  min, max;
-  int err = MP_MEM;
-
-  mp_digit *bds, *t1ds;
-
-  an = a->used;
-  bn = b->used;
-  if ((res = mp_grow(c, an + bn)) != MP_OKAY) {
-    return res;
-  }
-
-  if (mp_init_size(&t1, an) != MP_OKAY) {
-    goto ERR;
-  }
-
-  bds = b->dp;
-  t1ds = t1.dp;
-
-  n = 0;
-
-  mp_int x;
-
-  c->used = an + bn;
-  while (bn > 0) {
-    r = MIN(an, bn);
-    for (i = 0; i < r; ++i)
-      t1ds[i] = bds[n + i];
-    t1.used = r;
-
-    mp_init_size(&t2, an + r);
-    mp_mul(a, &t1, &t2);
-
-    if (t2.used > c->used - n) {
-      min = c->used - n; max = t2.used;
-      x.used = t2.used; x.dp = t2.dp;
-    } else {
-      min = t2.used; max = c->used - n;
-      x.used = c->used - n; x.dp = c->dp + n;
-    }
-
-    register mp_digit u, *tmpx, *tmpt2, *tmpcn;
-    register int j;
-    tmpx = tmpcn = x.dp; tmpt2 = t2.dp;
-    u = 0;
-    for (j = 0; j < min; j++) {
-      *tmpcn = *tmpx++ + *tmpt2++ + u;
-      u = *tmpcn >> ((mp_digit)DIGIT_BIT);
-      *tmpcn++ &= MP_MASK;
-    }
-    if (min != max) {
-      for (; j < max; j++) {
-        *tmpcn = x.dp[j] + u;
-        u = *tmpcn >> ((mp_digit)DIGIT_BIT);
-        *tmpcn++ &= MP_MASK;
-      }
-    }
-    *tmpcn++ = u;
-
-    bn -= r;
-    n += r;
-  }
-  mp_clamp(c);
-  return MP_OKAY;
-ERR:
-  return err;
-}
-#endif
-
-/* $Source$ */
-/* $Revision$ */
-/* $Date$ */

bn_mp_mul.c

@@ -21,27 +21,15 @@ int mp_mul (mp_int * a, mp_int * b, mp_int * c)
   int     res, neg;
   neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
 
-  int     an, bn, tn;
-  mp_int * t;
-  an = a -> used;
-  bn = b -> used;
-  if (an > bn) {
-    tn = an; an = bn; bn = tn;
-    t = a; a = b; b = t;
-  }
-  /* now a->used <= b->used */
-
   /* use Toom-Cook? */
 #ifdef BN_MP_TOOM_MUL_C
-  if (a->used >= TOOM_MUL_CUTOFF) {
+  if (MIN (a->used, b->used) >= TOOM_MUL_CUTOFF) {
-    if (2 * an <= bn) goto balance;
     res = mp_toom_mul(a, b, c);
   } else 
 #endif
 #ifdef BN_MP_KARATSUBA_MUL_C
   /* use Karatsuba? */
-  if (a->used >= KARATSUBA_MUL_CUTOFF) {
+  if (MIN (a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
-    if (2 * an <= bn) goto balance;
     res = mp_karatsuba_mul (a, b, c);
   } else 
 #endif
@@ -56,7 +44,8 @@ int mp_mul (mp_int * a, mp_int * b, mp_int * c)
 
 #ifdef BN_FAST_S_MP_MUL_DIGS_C
     if ((digs < MP_WARRAY) &&
-        a->used <= (1 << ((CHAR_BIT * sizeof (mp_word)) - (2 * DIGIT_BIT)))) {
+        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
@@ -67,17 +56,8 @@ int mp_mul (mp_int * a, mp_int * b, mp_int * c)
 #endif
 
   }
-ret:
   c->sign = (c->used > 0) ? neg : MP_ZPOS;
   return res;
-
-balance:
-  /* if a is much smaller than b
-   * use balance multiplication
-   * (the idea is taken from Ruby core)
-   */
-  res = mp_balance_mul(a, b, c);
-  goto ret;
 }
 #endif
 

tommath.h

@@ -577,7 +577,6 @@ int fast_s_mp_mul_high_digs(mp_int *a, mp_int *b, mp_int *c, int digs);
 int s_mp_mul_high_digs(mp_int *a, mp_int *b, mp_int *c, int digs);
 int fast_s_mp_sqr(mp_int *a, mp_int *b);
 int s_mp_sqr(mp_int *a, mp_int *b);
-int mp_balance_mul(mp_int *a, mp_int *b, mp_int *c);
 int mp_karatsuba_mul(mp_int *a, mp_int *b, mp_int *c);
 int mp_toom_mul(mp_int *a, mp_int *b, mp_int *c);
 int mp_karatsuba_sqr(mp_int *a, mp_int *b);

tommath_class.h

@@ -20,7 +20,6 @@
 #define BN_MP_ADD_D_C
 #define BN_MP_ADDMOD_C
 #define BN_MP_AND_C
-#define BN_MP_BALANCE_MUL_C
 #define BN_MP_CLAMP_C
 #define BN_MP_CLEAR_C
 #define BN_MP_CLEAR_MULTI_C