rewrite of bn_nist.c, disable support for some curves on 64 bit platforms

for now (it was broken anyway)

1 files changed, 231 insertions, 321 deletions

diff --git a/crypto/bn/bn_nist.c b/crypto/bn/bn_nist.c
index bbe2cbe..fa453a4 100644
--- a/crypto/bn/bn_nist.c
+++ b/crypto/bn/bn_nist.c
@@ -1,6 +1,9 @@
 /* crypto/bn/bn_nist.c */
+/*
+ * Written by Nils Larsch for the OpenSSL project
+ */
 /* ====================================================================
- * Copyright (c) 1998-2002 The OpenSSL Project.  All rights reserved.
+ * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -63,69 +66,69 @@
 #define BN_NIST_521_TOP	(521+BN_BITS2-1)/BN_BITS2
 
 #if BN_BITS2 == 64
-const static BN_ULONG _nist_p_192[] =
+static const BN_ULONG _nist_p_192[] =
 	{0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFEULL,
 	0xFFFFFFFFFFFFFFFFULL};
-const static BN_ULONG _nist_p_224[] =
+static const BN_ULONG _nist_p_224[] =
 	{0x0000000000000001ULL,0xFFFFFFFF00000000ULL,
 	0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL};
-const static BN_ULONG _nist_p_256[] =
+static const BN_ULONG _nist_p_256[] =
 	{0xFFFFFFFFFFFFFFFFULL,0x00000000FFFFFFFFULL,
 	0x0000000000000000ULL,0xFFFFFFFF00000001ULL};
-const static BN_ULONG _nist_p_384[] =
+static const BN_ULONG _nist_p_384[] =
 	{0x00000000FFFFFFFFULL,0xFFFFFFFF00000000ULL,
 	0xFFFFFFFFFFFFFFFEULL,0xFFFFFFFFFFFFFFFFULL,
 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL};
-const static BN_ULONG _nist_p_521[] =
+static const BN_ULONG _nist_p_521[] =
 	{0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
 	0xFFFFFFFFFFFFFFFFULL,0xFFFFFFFFFFFFFFFFULL,
 	0x00000000000001FFULL};
 #elif BN_BITS2 == 32
-const static BN_ULONG _nist_p_192[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,
+static const BN_ULONG _nist_p_192[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFE,
 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
-const static BN_ULONG _nist_p_224[] = {0x00000001,0x00000000,0x00000000,
+static const BN_ULONG _nist_p_224[] = {0x00000001,0x00000000,0x00000000,
 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
-const static BN_ULONG _nist_p_256[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
+static const BN_ULONG _nist_p_256[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 	0x00000000,0x00000000,0x00000000,0x00000001,0xFFFFFFFF};
-const static BN_ULONG _nist_p_384[] = {0xFFFFFFFF,0x00000000,0x00000000,
+static const BN_ULONG _nist_p_384[] = {0xFFFFFFFF,0x00000000,0x00000000,
 	0xFFFFFFFF,0xFFFFFFFE,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF};
-const static BN_ULONG _nist_p_521[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
+static const BN_ULONG _nist_p_521[] = {0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 	0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,0xFFFFFFFF,
 	0xFFFFFFFF,0x000001FF};
 #elif BN_BITS2 == 16
-const static BN_ULONG _nist_p_192[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFE,
+static const BN_ULONG _nist_p_192[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFE,
 	0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF};
-const static BN_ULONG _nist_p_224[] = {0x0001,0x0000,0x0000,0x0000,0x0000,
+static const BN_ULONG _nist_p_224[] = {0x0001,0x0000,0x0000,0x0000,0x0000,
 	0x0000,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF};
-const static BN_ULONG _nist_p_256[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
+static const BN_ULONG _nist_p_256[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
 	0xFFFF,0x0000,0x0000,0x0000,0x0000,0x0000,0x0000,0x0001,0x0000,0xFFFF,
 	0xFFFF};
-const static BN_ULONG _nist_p_384[] = {0xFFFF,0xFFFF,0x0000,0x0000,0x0000,
+static const BN_ULONG _nist_p_384[] = {0xFFFF,0xFFFF,0x0000,0x0000,0x0000,
 	0x0000,0xFFFF,0xFFFF,0xFFFE,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
 	0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF};
-const static BN_ULONG _nist_p_521[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
+static const BN_ULONG _nist_p_521[] = {0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
 	0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
 	0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,
 	0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0xFFFF,0x01FF};
 #elif BN_BITS2 == 8
-const static BN_ULONG _nist_p_192[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+static const BN_ULONG _nist_p_192[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF};
-const static BN_ULONG _nist_p_224[] = {0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
+static const BN_ULONG _nist_p_224[] = {0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
 	0x00,0x00,0x00,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
-const static BN_ULONG _nist_p_256[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+static const BN_ULONG _nist_p_256[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
 	0x00,0x00,0x01,0x00,0x00,0x00,0xFF,0xFF,0xFF,0xFF};
-const static BN_ULONG _nist_p_384[] = {0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,
+static const BN_ULONG _nist_p_384[] = {0xFF,0xFF,0xFF,0xFF,0x00,0x00,0x00,0x00,
 	0x00,0x00,0x00,0x00,0xFF,0xFF,0xFF,0xFF,0xFE,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
-const static BN_ULONG _nist_p_521[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
+static const BN_ULONG _nist_p_521[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 	0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
@@ -178,181 +181,116 @@ static int _is_set_384_data = 0;
 static void _init_384_data(void);
 
 #define BN_NIST_ADD_ONE(a)	while (!(++(*(a)))) ++(a);
-#define __buf_0			(BN_ULONG)0
-#define __buf_0_1		(BN_ULONG)0
-#define __buf_0_2		(BN_ULONG)0
+
+static void nist_cp_bn_0(BN_ULONG *buf, BN_ULONG *a, int top, int max)
+        {
+	int i;
+        BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
+        for (i = (top); i != 0; i--)
+                *_tmp1++ = *_tmp2++;
+        for (i = (max) - (top); i != 0; i--)
+                *_tmp1++ = (BN_ULONG) 0;
+        }
+
+static void nist_cp_bn(BN_ULONG *buf, BN_ULONG *a, int top)
+        { 
+	int i;
+        BN_ULONG *_tmp1 = (buf), *_tmp2 = (a);
+        for (i = (top); i != 0; i--)
+                *_tmp1++ = *_tmp2++;
+        }
+
 #if BN_BITS2 == 64
-#define BN_64_BIT_BUF(n)	BN_ULONG __buf_##n = (BN_ULONG)0;
-#define BN_CP_64_TO_BUF(n)	__buf_##n = (a)[(n)];
-#define BN_CP_64_FROM_BUF(a,n)	*(a)++ = __buf_##n;
-#define BN_CASE_64_BIT(n,a)	case (n): __buf_##n = (a)[(n)];
-#if	UINT_MAX == 4294967295UL
-#define	nist32	unsigned int
-#define BN_32_BIT_BUF(n)	nist32 __buf_##n = (nist32)0;
-#define BN_CP_32_TO_BUF(n)	__buf_##n = ((nist32 *)(a))[(n)];
-#define BN_CP_32_FROM_BUF(a,n)	*((nist32)(a))++ = __buf_##n;
-#define BN_CASE_32_BIT(n,a)	case (n): __buf_##n = ((nist32)(a))[(n)];
-#elif	ULONG_MAX == 4294967295UL
-#define	nist32	unsigned long
-#define BN_32_BIT_BUF(n)	nist32 __buf_##n = (nist32)0;
-#define BN_CP_32_TO_BUF(n)	__buf_##n = ((nist32 *)(a))[(n)];
-#define BN_CP_32_FROM_BUF(a,n)	*((nist32)(a))++ = __buf_##n;
-#define BN_CASE_32_BIT(n,a)	case (n): __buf_##n = ((nist32)(a))[(n)];
+#define bn_cp_64(to, n, from, m)	(to)[n] = (from)[m];
+#define bn_64_set_0(to, n)		(to)[n] = (BN_ULONG)0;
+/* TBD */
+#define bn_cp_32(to, n, from, m)	(to)[n] = (from)[m];
+#define bn_32_set_0(to, n)		(to)[n] = (BN_ULONG)0;
 #else
-#define	NO_32_BIT_TYPE
-#endif
-#elif BN_BITS2 == 32
-#define BN_64_BIT_BUF(n)	BN_ULONG __buf_##n##_1 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_2 = (BN_ULONG)0;
-#define BN_CP_64_TO_BUF(n)	__buf_##n##_2 = (a)[2*(n)+1];\
-				__buf_##n##_1 = (a)[2*(n)];
-#define BN_CP_64_FROM_BUF(a,n)	*(a)++ = __buf_##n##_1;\
-				*(a)++ = __buf_##n##_2;
-#define BN_CASE_64_BIT(n,a)	case 2*(n)+1: __buf_##n##_2 = (a)[2*(n)+1];\
-				case 2*(n):   __buf_##n##_1 = (a)[2*(n)];
-				
-#define BN_32_BIT_BUF(n)	BN_ULONG __buf_##n = (BN_ULONG)0;
-#define BN_CP_32_TO_BUF(n)	__buf_##n = (a)[(n)];
-#define BN_CP_32_FROM_BUF(a,n)	*(a)++ = __buf_##n;
-#define BN_CASE_32_BIT(n,a)	case (n): __buf_##n = (a)[(n)];
+#define bn_cp_64(to, n, from, m) \
+	{ \
+	bn_cp_32(to, (n)*2, from, (m)*2); \
+	bn_cp_32(to, (n)*2+1, from, (m)*2+1); \
+	}
+#define bn_64_set_0(to, n) \
+	{ \
+	bn_32_set_0(to, (n)*2); \
+	bn_32_set_0(to, (n)*2+1); \
+	}
+#if BN_BITS2 == 32
+#define bn_cp_32(to, n, from, m)	(to)[n] = (from)[m];
+#define bn_32_set_0(to, n)		(to)[n] = (BN_ULONG)0;
 #elif BN_BITS2 == 16
-#define __buf_0_3		(BN_ULONG)0
-#define __buf_0_4		(BN_ULONG)0
-#define BN_64_BIT_BUF(n)	BN_ULONG __buf_##n##_1 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_2 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_3 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_4 = (BN_ULONG)0;
-#define BN_CP_64_TO_BUF(n)	__buf_##n##_4 = (a)[4*(n)+3];\
-				__buf_##n##_3 = (a)[4*(n)+2];\
-				__buf_##n##_2 = (a)[4*(n)+1];\
-				__buf_##n##_1 = (a)[4*(n)];
-#define BN_CP_64_FROM_BUF(a,n)	*(a)++ = __buf_##n##_1;\
-				*(a)++ = __buf_##n##_2;\
-				*(a)++ = __buf_##n##_3;\
-				*(a)++ = __buf_##n##_4;
-#define BN_CASE_64_BIT(n,a)	case 4*(n)+3: __buf_##n##_4 = (a)[4*(n)+3];\
-				case 4*(n)+2: __buf_##n##_3 = (a)[4*(n)+2];\
-				case 4*(n)+1: __buf_##n##_2 = (a)[4*(n)+1];\
-				case 4*(n):   __buf_##n##_1 = (a)[4*(n)];
-#define BN_32_BIT_BUF(n)	BN_ULONG __buf_##n##_1 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_2 = (BN_ULONG)0;
-#define BN_CP_32_TO_BUF(n)	__buf_##n##_1 = (a)[2*(n)];\
-				__buf_##n##_2 = (a)[2*(n)+1];
-#define BN_CP_32_FROM_BUF(a,n)	*(a)++ = __buf_##n##_1;\
-				*(a)++ = __buf_##n##_2;
-#define BN_CASE_32_BIT(n,a)	case 2*(n)+1: __buf_##n##_2 = (a)[2*(n)+1];\
-				case 2*(n):   __buf_##n##_1 = (a)[2*(n)];
+#define bn_cp_32(to, n, from, m) \
+	{ \
+	(to)[(n)*2]   = (from)[(m)*2];  \
+	(to)[(n)*2+1] = (from)[(m)*2+1];\
+	}
+#define bn_32_set_0(to, n) { (to)[(n)*2] = 0; (to)[(n)*2+1] = 0; }
 #elif BN_BITS2 == 8
-#define __buf_0_3		(BN_ULONG)0
-#define __buf_0_4		(BN_ULONG)0
-#define __buf_0_5		(BN_ULONG)0
-#define __buf_0_6		(BN_ULONG)0
-#define __buf_0_7		(BN_ULONG)0
-#define __buf_0_8		(BN_ULONG)0
-#define BN_64_BIT_BUF(n)	BN_ULONG __buf_##n##_1 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_2 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_3 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_4 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_5 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_6 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_7 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_8 = (BN_ULONG)0;
-#define BN_CP_64_TO_BUF(n)	__buf_##n##_8 = (a)[8*(n)+7];\
-				__buf_##n##_7 = (a)[8*(n)+6];\
-				__buf_##n##_6 = (a)[8*(n)+5];\
-				__buf_##n##_5 = (a)[8*(n)+4];\
-				__buf_##n##_4 = (a)[8*(n)+3];\
-				__buf_##n##_3 = (a)[8*(n)+2];\
-				__buf_##n##_2 = (a)[8*(n)+1];\
-				__buf_##n##_1 = (a)[8*(n)];
-#define BN_CP_64_FROM_BUF(a,n)	*(a)++ = __buf_##n##_1;\
-				*(a)++ = __buf_##n##_2;\
-				*(a)++ = __buf_##n##_3;\
-				*(a)++ = __buf_##n##_4;\
-				*(a)++ = __buf_##n##_5;\
-				*(a)++ = __buf_##n##_6;\
-				*(a)++ = __buf_##n##_7;\
-				*(a)++ = __buf_##n##_8;
-#define BN_CASE_64_BIT(n,a)	case 8*(n)+7: __buf_##n##_8 = (a)[8*(n)+7];\
-				case 8*(n)+6: __buf_##n##_7 = (a)[8*(n)+6];\
-				case 8*(n)+5: __buf_##n##_6 = (a)[8*(n)+5];\
-				case 8*(n)+4: __buf_##n##_5 = (a)[8*(n)+4];\
-				case 8*(n)+3: __buf_##n##_4 = (a)[8*(n)+3];\
-				case 8*(n)+2: __buf_##n##_3 = (a)[8*(n)+2];\
-				case 8*(n)+1: __buf_##n##_2 = (a)[8*(n)+1];\
-				case 8*(n):   __buf_##n##_1 = (a)[8*(n)];
-#define BN_32_BIT_BUF(n)	BN_ULONG __buf_##n##_1 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_2 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_3 = (BN_ULONG)0;\
-				BN_ULONG __buf_##n##_4 = (BN_ULONG)0;
-#define BN_CP_32_TO_BUF(n)	__buf_##n##_1 = (a)[4*(n)];\
-				__buf_##n##_2 = (a)[4*(n)+1];\
-				__buf_##n##_3 = (a)[4*(n)+2];\
-				__buf_##n##_4 = (a)[4*(n)+3];
-#define BN_CP_32_FROM_BUF(a,n)	*(a)++ = __buf_##n##_1;\
-				*(a)++ = __buf_##n##_2;\
-				*(a)++ = __buf_##n##_3;\
-				*(a)++ = __buf_##n##_4;
-#define BN_CASE_32_BIT(n,a)	case 4*(n)+3: __buf_##n##_4 = (a)[4*(n)+3];\
-				case 4*(n)+2: __buf_##n##_3 = (a)[4*(n)+2];\
-				case 4*(n)+1: __buf_##n##_2 = (a)[4*(n)+1];\
-				case 4*(n):   __buf_##n##_1 = (a)[4*(n)];
+#define bn_cp_32(to, n, from, m) \
+	{ \
+	(to)[(n)*4]   = (from)[(m)*4];  \
+	(to)[(n)*4+1] = (from)[(m)*4+1];\
+	(to)[(n)*4+2] = (from)[(m)*4+2];\
+	(to)[(n)*4+3] = (from)[(m)*4+3];\
+	}
+#define bn_32_set_0(to, n) \
+	{ (to)[(n)*4]   = (BN_ULONG)0; (to)[(n)*4+1] = (BN_ULONG)0; \
+	  (to)[(n)*4+2] = (BN_ULONG)0; (to)[(n)*4+3] = (BN_ULONG)0; }
 #endif
+#endif /* BN_BITS2 != 64 */
 
 
-#define BN_192_SET(d,a1,a2,a3) \
-	{\
-	register BN_ULONG *td = (d);\
-	BN_CP_64_FROM_BUF(td,a3); BN_CP_64_FROM_BUF(td,a2);\
-	BN_CP_64_FROM_BUF(td,a1);\
+#define nist_set_192(to, from, a1, a2, a3) \
+	{ \
+	if (a3 != 0) bn_cp_64(to, 0, from, (a3) - 3) else bn_64_set_0(to, 0)\
+	bn_cp_64(to, 1, from, (a2) - 3) \
+	if (a1 != 0) bn_cp_64(to, 2, from, (a1) - 3) else bn_64_set_0(to, 2)\
 	}
 
 int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	BN_CTX *ctx)
 	{
-	int      top;
+	int      top = a->top, i;
 	BN_ULONG carry = 0;
-	register BN_ULONG *r_d, *a_d;
-	BN_ULONG t_d[BN_NIST_192_TOP];
-	BN_64_BIT_BUF(3)  BN_64_BIT_BUF(4)
-	BN_64_BIT_BUF(5)
+	register BN_ULONG *r_d, *a_d = a->d;
+	BN_ULONG t_d[BN_NIST_192_TOP],
+	         buf[BN_NIST_192_TOP];
 
-	top = BN_ucmp(field, a);
-	if (top == 0)
+	i = BN_ucmp(field, a);
+	if (i == 0)
 		{
 		BN_zero(r);
 		return 1;
 		}
-	else if (top > 0)
-		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
+	else if (i > 0)
+		return (r == a) ? 1 : (BN_copy(r ,a) != NULL);
 
-	if (r != a)
-		if (!BN_ncopy(r, a, BN_NIST_192_TOP))
-			return 0;
+	if (top == BN_NIST_192_TOP)
+		return BN_usub(r, a, field);
 
-	r_d = r->d;
-	a_d = a->d;
-	top = a->top-1;
-
-	switch (top)
+	if (r != a)
 		{
-		BN_CASE_64_BIT(5, a_d)
-		BN_CASE_64_BIT(4, a_d)
-		BN_CASE_64_BIT(3, a_d)
-			break;
-		default: /* a->top == field->top */
-			return BN_usub(r, a, field);
+		if (!bn_wexpand(r, BN_NIST_192_TOP))
+			return 0;
+		r_d = r->d;
+		nist_cp_bn(r_d, a_d, BN_NIST_192_TOP);
 		}
+	else
+		r_d = a_d;
 
-	BN_192_SET(t_d,0,3,3)
+	nist_cp_bn_0(buf, a_d + BN_NIST_192_TOP, top - BN_NIST_192_TOP, BN_NIST_192_TOP);
+
+	nist_set_192(t_d, buf, 0, 3, 3);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP))
 		++carry;
 
-	BN_192_SET(t_d,4,4,0)
+	nist_set_192(t_d, buf, 4, 4, 0);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP))
 		++carry;
 
-	BN_192_SET(t_d,5,5,5)
+	nist_set_192(t_d, buf, 5, 5, 5)
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_192_TOP))
 		++carry;
 
@@ -373,70 +311,61 @@ int BN_nist_mod_192(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	return 1;
 	}
 
-#define BN_224_SET(d,a1,a2,a3,a4,a5,a6,a7) \
-	{\
-	register BN_ULONG *td = (d);\
-	BN_CP_32_FROM_BUF(td,a7); BN_CP_32_FROM_BUF(td,a6);\
-	BN_CP_32_FROM_BUF(td,a5); BN_CP_32_FROM_BUF(td,a4);\
-	BN_CP_32_FROM_BUF(td,a3); BN_CP_32_FROM_BUF(td,a2);\
-	BN_CP_32_FROM_BUF(td,a1);\
+#define nist_set_224(to, from, a1, a2, a3, a4, a5, a6, a7) \
+	{ \
+	if (a7 != 0) bn_cp_32(to, 0, from, (a7) - 7) else bn_32_set_0(to, 0)\
+	if (a6 != 0) bn_cp_32(to, 1, from, (a6) - 7) else bn_32_set_0(to, 1)\
+	if (a5 != 0) bn_cp_32(to, 2, from, (a5) - 7) else bn_32_set_0(to, 2)\
+	if (a4 != 0) bn_cp_32(to, 3, from, (a4) - 7) else bn_32_set_0(to, 3)\
+	if (a3 != 0) bn_cp_32(to, 4, from, (a3) - 7) else bn_32_set_0(to, 4)\
+	if (a2 != 0) bn_cp_32(to, 5, from, (a2) - 7) else bn_32_set_0(to, 5)\
+	if (a1 != 0) bn_cp_32(to, 6, from, (a1) - 7) else bn_32_set_0(to, 6)\
 	}
 
 int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	BN_CTX *ctx)
 	{
-#ifndef NO_32_BIT_TYPE
-	int	tmp_int;
+#if BN_BITS2 != 64
+	int	top = a->top, i;
 	int	carry = 0;
-	BN_ULONG *r_d, *a_d;
-	BN_ULONG t_d[BN_NIST_224_TOP];
-	BN_32_BIT_BUF(7)  BN_32_BIT_BUF(8)
-	BN_32_BIT_BUF(9)  BN_32_BIT_BUF(10)
-	BN_32_BIT_BUF(11) BN_32_BIT_BUF(12)
-	BN_32_BIT_BUF(13)
-
-	tmp_int = BN_ucmp(field, a);
-	if (tmp_int == 0)
+	BN_ULONG *r_d, *a_d = a->d;
+	BN_ULONG t_d[BN_NIST_224_TOP],
+	         buf[BN_NIST_224_TOP];
+
+	i = BN_ucmp(field, a);
+	if (i == 0)
 		{
 		BN_zero(r);
 		return 1;
 		}
-	else if (tmp_int > 0)
+	else if (i > 0)
 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 
-	if (r != a)
-		if (!BN_ncopy(r, a, BN_NIST_224_TOP))
-			return 0;
-
-	r_d = r->d;
-	a_d = a->d;
-
-	tmp_int = a->top-1;
+	if (top == BN_NIST_224_TOP)
+		return BN_usub(r, a, field);
 
-	switch (tmp_int)
+	if (r != a)
 		{
-		BN_CASE_32_BIT(13, a_d)
-		BN_CASE_32_BIT(12, a_d)
-		BN_CASE_32_BIT(11, a_d)
-		BN_CASE_32_BIT(10, a_d)
-		BN_CASE_32_BIT(9,  a_d)
-		BN_CASE_32_BIT(8,  a_d)
-		BN_CASE_32_BIT(7,  a_d)
-			break;
-		default: /* a->top == field->top */
-			return BN_usub(r, a, field);
+		if (!bn_wexpand(r, BN_NIST_224_TOP))
+			return 0;
+		r_d = r->d;
+		nist_cp_bn(r_d, a_d, BN_NIST_224_TOP);
 		}
+	else
+		r_d = a_d;
 
-	BN_224_SET(t_d,10,9,8,7,0,0,0)
+	nist_cp_bn_0(buf, a_d + BN_NIST_224_TOP, top - BN_NIST_224_TOP, BN_NIST_224_TOP);
+
+	nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP))
 		++carry;
-	BN_224_SET(t_d,0,13,12,11,0,0,0)
+	nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP))
 		++carry;
-	BN_224_SET(t_d,13,12,11,10,9,8,7)
+	nist_set_224(t_d, buf, 13, 12, 11, 10, 9, 8, 7);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP))
 		--carry;
-	BN_224_SET(t_d,0,0,0,0,13,12,11)
+	nist_set_224(t_d, buf, 0, 0, 0, 0, 13, 12, 11);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP))
 		--carry;
 
@@ -485,28 +414,28 @@ static void _init_256_data(void)
 	_is_set_256_data = 1;
 	}
 
-#define BN_256_SET(d,a1,a2,a3,a4,a5,a6,a7,a8) \
-	{\
-	register BN_ULONG *td = (d);\
-	BN_CP_32_FROM_BUF(td,a8); BN_CP_32_FROM_BUF(td,a7);\
-	BN_CP_32_FROM_BUF(td,a6); BN_CP_32_FROM_BUF(td,a5);\
-	BN_CP_32_FROM_BUF(td,a4); BN_CP_32_FROM_BUF(td,a3);\
-	BN_CP_32_FROM_BUF(td,a2); BN_CP_32_FROM_BUF(td,a1);\
+#define nist_set_256(to, from, a1, a2, a3, a4, a5, a6, a7, a8) \
+	{ \
+	if (a8 != 0) bn_cp_32(to, 0, from, (a8) - 8) else bn_32_set_0(to, 0)\
+	if (a7 != 0) bn_cp_32(to, 1, from, (a7) - 8) else bn_32_set_0(to, 1)\
+	if (a6 != 0) bn_cp_32(to, 2, from, (a6) - 8) else bn_32_set_0(to, 2)\
+	if (a5 != 0) bn_cp_32(to, 3, from, (a5) - 8) else bn_32_set_0(to, 3)\
+	if (a4 != 0) bn_cp_32(to, 4, from, (a4) - 8) else bn_32_set_0(to, 4)\
+	if (a3 != 0) bn_cp_32(to, 5, from, (a3) - 8) else bn_32_set_0(to, 5)\
+	if (a2 != 0) bn_cp_32(to, 6, from, (a2) - 8) else bn_32_set_0(to, 6)\
+	if (a1 != 0) bn_cp_32(to, 7, from, (a1) - 8) else bn_32_set_0(to, 7)\
 	}
 
 int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	BN_CTX *ctx)
 	{
-#ifndef NO_32_BIT_TYPE
-	int	tmp_int;
+#if BN_BITS2 != 64
+	int	i, top = a->top;
 	int	carry = 0;
-	register BN_ULONG *a_d, *r_d;
-	BN_ULONG t_d[BN_NIST_256_TOP];
-	BN_ULONG t_d2[BN_NIST_256_TOP];
-	BN_32_BIT_BUF(8)  BN_32_BIT_BUF(9)
-	BN_32_BIT_BUF(10) BN_32_BIT_BUF(11)
-	BN_32_BIT_BUF(12) BN_32_BIT_BUF(13)
-	BN_32_BIT_BUF(14) BN_32_BIT_BUF(15)
+	register BN_ULONG *a_d = a->d, *r_d;
+	BN_ULONG t_d[BN_NIST_256_TOP],
+	         t_d2[BN_NIST_256_TOP],
+	         buf[BN_NIST_256_TOP];
 
 	if (!_is_set_256_data)
 		{
@@ -518,42 +447,34 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 		CRYPTO_w_unlock(CRYPTO_LOCK_BN);
 		}
 	
-	tmp_int = BN_ucmp(field, a);
-	if (tmp_int == 0)
+	i = BN_ucmp(field, a);
+	if (i == 0)
 		{
 		BN_zero(r);
 		return 1;
 		}
-	else if (tmp_int > 0)
+	else if (i > 0)
 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 
-	if (r != a)
-		if (!BN_ncopy(r, a, BN_NIST_256_TOP))
-			return 0;
-
-	tmp_int = a->top-1;
+	if (top == BN_NIST_256_TOP)
+		return BN_usub(r, a, field);
 
-	a_d = a->d;
-	r_d = r->d;
-	switch (tmp_int)
+	if (r != a)
 		{
-		BN_CASE_32_BIT(15, a_d)
-		BN_CASE_32_BIT(14, a_d)
-		BN_CASE_32_BIT(13, a_d)
-		BN_CASE_32_BIT(12, a_d)
-		BN_CASE_32_BIT(11, a_d)
-		BN_CASE_32_BIT(10, a_d)
-		BN_CASE_32_BIT(9,  a_d)
-		BN_CASE_32_BIT(8,  a_d)
-			break;
-		default: /* a->top == field->top */
-			return BN_usub(r, a, field);
+		if (!bn_wexpand(r, BN_NIST_256_TOP))
+			return 0;
+		r_d = r->d;
+		nist_cp_bn(r_d, a_d, BN_NIST_256_TOP);
 		}
+	else
+		r_d = a_d;
+
+	nist_cp_bn_0(buf, a_d + BN_NIST_256_TOP, top - BN_NIST_256_TOP, BN_NIST_256_TOP);
 
 	/*S1*/
-	BN_256_SET(t_d,15,14,13,12,11,0,0,0)
+	nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
 	/*S2*/
-	BN_256_SET(t_d2,0,15,14,13,12,0,0,0)
+	nist_set_256(t_d2,buf, 0, 15, 14, 13, 12, 0, 0, 0);
 	if (bn_add_words(t_d, t_d, t_d2, BN_NIST_256_TOP))
 		carry = 2;
 	/* left shift */
@@ -561,7 +482,7 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 		register BN_ULONG *ap,t,c;
 		ap = t_d;
 		c=0;
-		for (tmp_int=BN_NIST_256_TOP; tmp_int != 0; --tmp_int)
+		for (i = BN_NIST_256_TOP; i != 0; --i)
 			{
 			t= *ap;
 			*(ap++)=((t<<1)|c)&BN_MASK2;
@@ -574,27 +495,27 @@ int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		++carry;
 	/*S3*/
-	BN_256_SET(t_d,15,14,0,0,0,10,9,8)
+	nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		++carry;
 	/*S4*/
-	BN_256_SET(t_d,8,13,15,14,13,11,10,9)
+	nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		++carry;
 	/*D1*/
-	BN_256_SET(t_d,10,8,0,0,0,13,12,11)
+	nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		--carry;
 	/*D2*/
-	BN_256_SET(t_d,11,9,0,0,15,14,13,12)
+	nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		--carry;
 	/*D3*/
-	BN_256_SET(t_d,12,0,10,9,8,15,14,13)
+	nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		--carry;
 	/*D4*/
-	BN_256_SET(t_d,13,0,11,10,9,0,15,14)
+	nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
 		--carry;
 	
@@ -643,31 +564,31 @@ static void _init_384_data(void)
 	_is_set_384_data = 1;
 	}
 
-#define BN_384_SET(d,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
-	{\
-	register BN_ULONG *td = (d);\
-	BN_CP_32_FROM_BUF(td,a12); BN_CP_32_FROM_BUF(td,a11);\
-	BN_CP_32_FROM_BUF(td,a10); BN_CP_32_FROM_BUF(td,a9);\
-	BN_CP_32_FROM_BUF(td,a8);  BN_CP_32_FROM_BUF(td,a7);\
-	BN_CP_32_FROM_BUF(td,a6);  BN_CP_32_FROM_BUF(td,a5);\
-	BN_CP_32_FROM_BUF(td,a4);  BN_CP_32_FROM_BUF(td,a3);\
-	BN_CP_32_FROM_BUF(td,a2);  BN_CP_32_FROM_BUF(td,a1);\
+#define nist_set_384(to,from,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
+	{ \
+	if (a12 != 0) bn_cp_32(to, 0, from,  (a12) - 12) else bn_32_set_0(to, 0)\
+	if (a11 != 0) bn_cp_32(to, 1, from,  (a11) - 12) else bn_32_set_0(to, 1)\
+	if (a10 != 0) bn_cp_32(to, 2, from,  (a10) - 12) else bn_32_set_0(to, 2)\
+	if (a9 != 0)  bn_cp_32(to, 3, from,  (a9) - 12)  else bn_32_set_0(to, 3)\
+	if (a8 != 0)  bn_cp_32(to, 4, from,  (a8) - 12)  else bn_32_set_0(to, 4)\
+	if (a7 != 0)  bn_cp_32(to, 5, from,  (a7) - 12)  else bn_32_set_0(to, 5)\
+	if (a6 != 0)  bn_cp_32(to, 6, from,  (a6) - 12)  else bn_32_set_0(to, 6)\
+	if (a5 != 0)  bn_cp_32(to, 7, from,  (a5) - 12)  else bn_32_set_0(to, 7)\
+	if (a4 != 0)  bn_cp_32(to, 8, from,  (a4) - 12)  else bn_32_set_0(to, 8)\
+	if (a3 != 0)  bn_cp_32(to, 9, from,  (a3) - 12)  else bn_32_set_0(to, 9)\
+	if (a2 != 0)  bn_cp_32(to, 10, from, (a2) - 12)  else bn_32_set_0(to, 10)\
+	if (a1 != 0)  bn_cp_32(to, 11, from, (a1) - 12)  else bn_32_set_0(to, 11)\
 	}
 
 int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	BN_CTX *ctx)
 	{
-#ifndef NO_32_BIT_TYPE
-	int	tmp_int;
+#if BN_BITS2 != 64
+	int	i, top = a->top;
 	int	carry = 0;
-	register BN_ULONG *r_d, *a_d;
-	BN_ULONG t_d[BN_NIST_384_TOP];
-	BN_32_BIT_BUF(12) BN_32_BIT_BUF(13)
-	BN_32_BIT_BUF(14) BN_32_BIT_BUF(15)
-	BN_32_BIT_BUF(16) BN_32_BIT_BUF(17)
-	BN_32_BIT_BUF(18) BN_32_BIT_BUF(19)
-	BN_32_BIT_BUF(20) BN_32_BIT_BUF(21)
-	BN_32_BIT_BUF(22) BN_32_BIT_BUF(23)
+	register BN_ULONG *r_d, *a_d = a->d;
+	BN_ULONG t_d[BN_NIST_384_TOP],
+	         buf[BN_NIST_384_TOP];
 
 	if (!_is_set_384_data)
 		{
@@ -679,50 +600,38 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 		CRYPTO_w_unlock(CRYPTO_LOCK_BN);
 		}
 
-	tmp_int = BN_ucmp(field, a);
-	if (tmp_int == 0)
+	i = BN_ucmp(field, a);
+	if (i == 0)
 		{
 		BN_zero(r);
 		return 1;
 		}
-	else if (tmp_int > 0)
+	else if (i > 0)
 		return (r == a)? 1 : (BN_copy(r ,a) != NULL);
 
-	if (r != a)
-		if (!BN_ncopy(r, a, BN_NIST_384_TOP))
-			return 0;
-
-	r_d = r->d;
-	a_d = a->d;
-	tmp_int = a->top-1;
+	if (top == BN_NIST_384_TOP)
+		return BN_usub(r, a, field);
 
-	switch (tmp_int)
+	if (r != a)
 		{
-		BN_CASE_32_BIT(23, a_d)
-		BN_CASE_32_BIT(22, a_d)
-		BN_CASE_32_BIT(21, a_d)
-		BN_CASE_32_BIT(20, a_d)
-		BN_CASE_32_BIT(19, a_d)
-		BN_CASE_32_BIT(18, a_d)
-		BN_CASE_32_BIT(17, a_d)
-		BN_CASE_32_BIT(16, a_d)
-		BN_CASE_32_BIT(15, a_d)
-		BN_CASE_32_BIT(14, a_d)
-		BN_CASE_32_BIT(13, a_d)
-		BN_CASE_32_BIT(12, a_d)
-			break;
-		default: /* a->top == field->top */
-			return BN_usub(r, a, field);
+		if (!bn_wexpand(r, BN_NIST_384_TOP))
+			return 0;
+		r_d = r->d;
+		nist_cp_bn(r_d, a_d, BN_NIST_384_TOP);
 		}
+	else
+		r_d = a_d;
+
+	nist_cp_bn_0(buf, a_d + BN_NIST_384_TOP, top - BN_NIST_384_TOP, BN_NIST_384_TOP);
 
 	/*S1*/
-	BN_256_SET(t_d,0,0,0,0,0,23,22,21)
+	nist_set_256(t_d, buf, 0, 0, 0, 0, 0, 23-4, 22-4, 21-4);
 		/* left shift */
 		{
 		register BN_ULONG *ap,t,c;
 		ap = t_d;
 		c=0;
-		for (tmp_int=BN_NIST_256_TOP; tmp_int != 0; --tmp_int)
+		for (i = BN_NIST_256_TOP; i != 0; --i)
 			{
 			t= *ap;
 			*(ap++)=((t<<1)|c)&BN_MASK2;
@@ -732,37 +641,36 @@ int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	if (bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
 		t_d, BN_NIST_256_TOP))
 		++carry;
-	/*S2*/
-	BN_384_SET(t_d,23,22,21,20,19,18,17,16,15,14,13,12)
-	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
+	/*S2 */
+	if (bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP))
 		++carry;
 	/*S3*/
-	BN_384_SET(t_d,20,19,18,17,16,15,14,13,12,23,22,21)
+	nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 		++carry;
 	/*S4*/
-	BN_384_SET(t_d,19,18,17,16,15,14,13,12,20,0,23,0)
+	nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 		++carry;
 	/*S5*/
-	BN_256_SET(t_d,0,0,0,0,23,22,21,20)
+	nist_set_256(t_d, buf, 0, 0, 0, 0, 23-4, 22-4, 21-4, 20-4);
 	if (bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
 		t_d, BN_NIST_256_TOP))
 		++carry;
 	/*S6*/
-	BN_384_SET(t_d,0,0,0,0,0,0,23,22,21,0,0,20)
+	nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
 	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 		++carry;
 	/*D1*/
-	BN_384_SET(t_d,22,21,20,19,18,17,16,15,14,13,12,23)
+	nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 		--carry;
 	/*D2*/
-	BN_384_SET(t_d,0,0,0,0,0,0,0,23,22,21,20,0)
+	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 		--carry;
 	/*D3*/
-	BN_384_SET(t_d,0,0,0,0,0,0,0,23,23,0,0,0)
+	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
 	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
 		--carry;
 	
@@ -820,17 +728,19 @@ int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
 	if (!tmp)
 		goto err;
 
-	if (!BN_ncopy(tmp, a, BN_NIST_521_TOP))
-		return 0;
-	if (!BN_rshift(r, a, 521))
-		return 0;
-
-	if (tmp->top == BN_NIST_521_TOP)
-		tmp->d[BN_NIST_521_TOP-1]  &= BN_NIST_521_TOP_MASK;
+	if (!bn_wexpand(tmp, BN_NIST_521_TOP))
+		goto err;
+	nist_cp_bn(tmp->d, a->d, BN_NIST_521_TOP);
 
+	tmp->top = BN_NIST_521_TOP;
+        tmp->d[BN_NIST_521_TOP-1]  &= BN_NIST_521_TOP_MASK;
 	bn_correct_top(tmp);
+
+	if (!BN_rshift(r, a, 521))
+		goto err;
+
 	if (!BN_uadd(r, tmp, r))
-		return 0;
+		goto err;
 	top = r->top;
 	r_d = r->d;
 	if (top == BN_NIST_521_TOP  &&