From b425b0ea1f71a795134823f8e074732f32ee5fd8 Mon Sep 17 00:00:00 2001
From: Steffen Jaeckel <s@jaeckel.eu>
Date: Sat, 18 Oct 2014 18:54:06 +0200
Subject: [PATCH] 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 | 101 --------------------------------------------
bn_mp_mul.c | 28 ++----------
tommath.h | 1 -
tommath_class.h | 1 -
4 files changed, 4 insertions(+), 127 deletions(-)
delete mode 100644 bn_mp_balance_mul.c
diff --git a/bn_mp_balance_mul.c b/bn_mp_balance_mul.c
deleted file mode 100644
index 17ddedf..0000000
--- a/bn_mp_balance_mul.c
+++ /dev/null
@@ -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
-
-/* $Source$ */
-/* $Revision$ */
-/* $Date$ */
diff --git a/bn_mp_mul.c b/bn_mp_mul.c
index 4fdf5ac..64e32cc 100644
--- a/bn_mp_mul.c
+++ b/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 (2 * an <= bn) goto balance;
+ 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 (a->used >= KARATSUBA_MUL_CUTOFF) {
- if (2 * an <= bn) goto balance;
+ if (MIN (a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
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
diff --git a/tommath.h b/tommath.h
index 13cc64a..800d4b6 100644
--- a/tommath.h
+++ b/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);
diff --git a/tommath_class.h b/tommath_class.h
index afd08a4..a06d186 100644
--- a/tommath_class.h
+++ 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