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@

1 files changed, 15 insertions, 49 deletions

diff --git a/src/lib/libcrypto/bn/bn_div.c b/src/lib/libcrypto/bn/bn_div.c
index e8f17fff03..acacfb1a8c 100644
--- a/src/lib/libcrypto/bn/bn_div.c
+++ b/src/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;