Simplify bn_div_3_words().

Make use of bn_umul_hilo() and remove the tangle of preprocessor directives
that implement different code paths depending on what defines exist.

ok tb@

diff --git a/lib/libcrypto/bn/bn_div.c b/lib/libcrypto/bn/bn_div.c
index e8f17ff..acacfb1 100644 (file)
--- a/lib/libcrypto/bn/bn_div.c
+++ b/lib/libcrypto/bn/bn_div.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_div.c,v 1.35 2023/01/28 16:58:24 jsing Exp $ */
+/* $OpenBSD: bn_div.c,v 1.36 2023/01/31 06:08:23 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -66,6 +66,7 @@
 
 #include "bn_arch.h"
 #include "bn_local.h"
+#include "bn_internal.h"
 
 BN_ULONG bn_div_3_words(const BN_ULONG *m, BN_ULONG d1, BN_ULONG d0);
 
@@ -191,7 +192,7 @@ bn_div_rem_words(BN_ULONG h, BN_ULONG l, BN_ULONG d, BN_ULONG *out_q,
 BN_ULONG
 bn_div_3_words(const BN_ULONG *m, BN_ULONG d1, BN_ULONG d0)
 {
-       BN_ULONG n0, n1, q;
+       BN_ULONG n0, n1, q, t2h, t2l;
        BN_ULONG rem = 0;
 
        n0 = m[0];
@@ -201,55 +202,20 @@ bn_div_3_words(const BN_ULONG *m, BN_ULONG d1, BN_ULONG d0)
                return BN_MASK2;
 
        /* n0 < d0 */
-       {
-#ifdef BN_LLONG
-               BN_ULLONG t2;
+       bn_div_rem_words(n0, n1, d0, &q, &rem);
 
-               bn_div_rem_words(n0, n1, d0, &q, &rem);
+       bn_umul_hilo(d1, q, &t2h, &t2l);
 
-               t2 = (BN_ULLONG)d1 * q;
-
-               for (;;) {
-                       if (t2 <= (((BN_ULLONG)rem << BN_BITS2) | m[-2]))
-                               break;
-                       q--;
-                       rem += d0;
-                       if (rem < d0) break; /* don't let rem overflow */
-                               t2 -= d1;
-               }
-#else /* !BN_LLONG */
-               BN_ULONG t2l, t2h;
-
-               bn_div_rem_words(n0, n1, d0, &q, &rem);
-
-#if defined(BN_UMULT_LOHI)
-               BN_UMULT_LOHI(t2l, t2h, d1, q);
-#elif defined(BN_UMULT_HIGH)
-               t2l = d1 * q;
-               t2h = BN_UMULT_HIGH(d1, q);
-#else
-               {
-                       BN_ULONG ql, qh;
-                       t2l = LBITS(d1);
-                       t2h = HBITS(d1);
-                       ql = LBITS(q);
-                       qh = HBITS(q);
-                       mul64(t2l, t2h, ql, qh); /* t2 = (BN_ULLONG)d1 * q; */
-               }
-#endif
-
-               for (;;) {
-                       if (t2h < rem || (t2h == rem && t2l <= m[-2]))
-                               break;
-                       q--;
-                       rem += d0;
-                       if (rem < d0)
-                               break; /* don't let rem overflow */
-                       if (t2l < d1)
-                               t2h--;
-                       t2l -= d1;
-               }
-#endif /* !BN_LLONG */
+       for (;;) {
+               if (t2h < rem || (t2h == rem && t2l <= m[-2]))
+                       break;
+               q--;
+               rem += d0;
+               if (rem < d0)
+                       break; /* don't let rem overflow */
+               if (t2l < d1)
+                       t2h--;
+               t2l -= d1;
        }
 
        return q;