/* -*-c-*-
*
- * $Id: mpx-ksqr.c,v 1.4 2000/07/29 17:04:02 mdw Exp $
+ * $Id: mpx-ksqr.c,v 1.7 2002/10/09 00:36:03 mdw Exp $
*
* Karatsuba-based squaring algorithm
*
/*----- Revision history --------------------------------------------------*
*
* $Log: mpx-ksqr.c,v $
+ * Revision 1.7 2002/10/09 00:36:03 mdw
+ * Fix bounds on workspace for Karatsuba operations.
+ *
+ * Revision 1.6 2000/10/08 15:48:35 mdw
+ * Rename Karatsuba constants now that we have @gfx_kmul@ too.
+ *
+ * Revision 1.5 2000/10/08 12:11:01 mdw
+ * Use @mpx_ueq@ instead of @MPX_UCMP@.
+ *
* Revision 1.4 2000/07/29 17:04:02 mdw
* Remove useless header `mpscan.h'.
*
#include <stdio.h>
#include "mpx.h"
-#include "mpx-kmac.h"
+#include "karatsuba.h"
/*----- Tweakables --------------------------------------------------------*/
#ifdef TEST_RIG
-# undef KARATSUBA_CUTOFF
-# define KARATSUBA_CUTOFF 2
+# undef MPK_THRESH
+# define MPK_THRESH 4
#endif
/*----- Main code ---------------------------------------------------------*/
* large numbers, although more expensive on small ones, and
* rather simpler than full-blown Karatsuba multiplication.
*
- * The destination must be twice as large as the argument. The
- * scratch space must be twice as large as the argument, plus
- * the magic number @KARATSUBA_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_ksqr(mpw *dv, mpw *dvl,
MPX_SHRINK(av, avl);
- if (avl - av <= KARATSUBA_CUTOFF) {
+ if (avl - av <= MPK_THRESH) {
mpx_usqr(dv, dvl, av, avl);
return;
}
m = (avl - av + 1) >> 1;
avm = av + m;
- assert(((void)"Destination too small for Karatsuba square",
- dvl - dv >= 4 * m));
- assert(((void)"Not enough workspace for Karatsuba square",
- svl - sv >= 4 * m));
-
/* --- Sort out everything --- */
{
mpw *tdv = dv + m;
mpw *rdv = tdv + m;
+ assert(rdv + m + 4 < dvl);
+ assert(ssv < svl);
UADD2(sv, svm, av, avm, avm, avl);
- if (m > KARATSUBA_CUTOFF)
+ if (m > MPK_THRESH)
mpx_ksqr(tdv, rdv + m + 4, sv, svm + 1, ssv, svl);
else
mpx_usqr(tdv, rdv + m + 4, sv, svm + 1);
- if (m > KARATSUBA_CUTOFF)
+ if (m > MPK_THRESH)
mpx_ksqr(sv, ssv, avm, avl, ssv, svl);
else
mpx_usqr(sv, ssv, avm, avl);
UADD(rdv, sv, svm + 1);
USUB(tdv, sv, svn);
- if (m > KARATSUBA_CUTOFF)
+ if (m > MPK_THRESH)
mpx_ksqr(sv, ssv, av, avm, ssv, svl);
else
mpx_usqr(sv, ssv, av, avm);
LOAD(a, al, &v[0]);
LOAD(c, cl, &v[1]);
m = al - a + 1;
- ALLOC(d, dl, 2 * m);
- ALLOC(s, sl, 2 * m + 32);
+ ALLOC(d, dl, 3 * m);
+ ALLOC(s, sl, 5 * m);
mpx_ksqr(d, dl, a, al, s, sl);
- if (MPX_UCMP(d, dl, !=, c, cl)) {
+ if (!mpx_ueq(d, dl, c, cl)) {
fprintf(stderr, "\n*** usqr failed\n");
dumpmp(" a", a, al);
dumpmp("expected", c, cl);