X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/52cdaca9b7b8e15871a3de8b5b571c18dcc580f8..025c5f4aa5ffbf8948482a4233318db81c2df5d2:/mpx-kmul.c

diff --git a/mpx-kmul.c b/mpx-kmul.c
index f6b0b4f..94a2cda 100644
--- a/mpx-kmul.c
+++ b/mpx-kmul.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpx-kmul.c,v 1.7 2000/10/08 15:48:35 mdw Exp $
+ * $Id$
  *
  * Karatsuba's multiplication algorithm
  *
@@ -27,33 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: mpx-kmul.c,v $
- * Revision 1.7  2000/10/08 15:48:35  mdw
- * Rename Karatsuba constants now that we have @gfx_kmul@ too.
- *
- * Revision 1.6  2000/10/08 12:11:01  mdw
- * Use @mpx_ueq@ instead of @MPX_UCMP@.
- *
- * Revision 1.5  2000/07/29 17:04:02  mdw
- * Remove useless header `mpscan.h'.
- *
- * Revision 1.4  2000/06/17 11:42:11  mdw
- * Moved the Karatsuba macros into a separate file for better sharing.
- * Fixed some comments.
- *
- * Revision 1.3  1999/12/13 15:35:01  mdw
- * Simplify and improve.
- *
- * Revision 1.2  1999/12/11 10:58:02  mdw
- * Remove tweakable comments.
- *
- * Revision 1.1  1999/12/10 23:23:51  mdw
- * Karatsuba-Ofman multiplication algorithm.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <assert.h>
@@ -66,7 +39,7 @@
 
 #ifdef TEST_RIG
 #  undef MPK_THRESH
-#  define MPK_THRESH 2
+#  define MPK_THRESH 4			/* Smallest possible correct value */
 #endif
 
 /*----- Main code ---------------------------------------------------------*/
@@ -85,9 +58,9 @@
  *		multiplication (e.g., @mpx_umul@) on large numbers, although
  *		more expensive on small ones.
  *
- *		The destination must be twice as large as the larger
- *		argument.  The scratch space must be twice as large as the
- *		larger argument, plus the magic number @MPK_SLOP@.
+ *		The destination must be three times as large as the larger
+ *		argument.  The scratch space must be five times as large as
+ *		the larger argument.
  */
 
 void mpx_kmul(mpw *dv, mpw *dvl,
@@ -149,17 +122,14 @@ void mpx_kmul(mpw *dv, mpw *dvl,
       avm = avl;
   }
 
-  assert(((void)"Destination too small for Karatsuba multiply",
-	  dvl - dv >= 4 * m));
-  assert(((void)"Not enough workspace for Karatsuba multiply",
-	  svl - sv >= 4 * m));
-
   /* --- Sort out the middle term --- */
 
   {
     mpw *bsv = sv + m + 1, *ssv = bsv + m + 1;
     mpw *rdv = dv + m, *rdvl = rdv + 2 * (m + 2);
 
+    assert(rdvl <= dvl);
+    assert(ssv <= svl);
     UADD2(sv, bsv, av, avm, avm, avl);
     UADD2(bsv, ssv, bv, bvm, bvm, bvl);
     if (m > MPK_THRESH)
@@ -246,8 +216,8 @@ static int umul(dstr *v)
   LOAD(b, bl, &v[1]);
   LOAD(c, cl, &v[2]);
   m = MAX(al - a, bl - b) + 1;
-  ALLOC(d, dl, 2 * m);
-  ALLOC(s, sl, 2 * m + 32);
+  ALLOC(d, dl, 3 * m);
+  ALLOC(s, sl, 5 * m);
 
   mpx_kmul(d, dl, a, al, b, bl, s, sl);
   if (!mpx_ueq(d, dl, c, cl)) {
@@ -259,7 +229,7 @@ static int umul(dstr *v)
     ok = 0;
   }
 
-  free(a); free(b); free(c); free(d); free(s);
+  xfree(a); xfree(b); xfree(c); xfree(d); xfree(s);
   return (ok);
 }