1 files changed, 334 insertions, 158 deletions

diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index bfe7628ad4..5d62d88e8b 100644
--- a/src/lib/libcrypto/bn/bn_lib.c
+++ b/src/lib/libcrypto/bn/bn_lib.c
@@ -60,9 +60,68 @@
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
-char *BN_version="Big Number part of SSLeay 0.9.0b 29-Jun-1998";
+const char *BN_version="Big Number" OPENSSL_VERSION_PTEXT;
+
+/* For a 32 bit machine
+ * 2 -   4 ==  128
+ * 3 -   8 ==  256
+ * 4 -  16 ==  512
+ * 5 -  32 == 1024
+ * 6 -  64 == 2048
+ * 7 - 128 == 4096
+ * 8 - 256 == 8192
+ */
+OPENSSL_GLOBAL int bn_limit_bits=0;
+OPENSSL_GLOBAL int bn_limit_num=8;        /* (1<<bn_limit_bits) */
+OPENSSL_GLOBAL int bn_limit_bits_low=0;
+OPENSSL_GLOBAL int bn_limit_num_low=8;    /* (1<<bn_limit_bits_low) */
+OPENSSL_GLOBAL int bn_limit_bits_high=0;
+OPENSSL_GLOBAL int bn_limit_num_high=8;   /* (1<<bn_limit_bits_high) */
+OPENSSL_GLOBAL int bn_limit_bits_mont=0;
+OPENSSL_GLOBAL int bn_limit_num_mont=8;   /* (1<<bn_limit_bits_mont) */
+
+void BN_set_params(int mult, int high, int low, int mont)
+        {
+        if (mult >= 0)
+                {
+                if (mult > (sizeof(int)*8)-1)
+                        mult=sizeof(int)*8-1;
+                bn_limit_bits=mult;
+                bn_limit_num=1<<mult;
+                }
+        if (high >= 0)
+                {
+                if (high > (sizeof(int)*8)-1)
+                        high=sizeof(int)*8-1;
+                bn_limit_bits_high=high;
+                bn_limit_num_high=1<<high;
+                }
+        if (low >= 0)
+                {
+                if (low > (sizeof(int)*8)-1)
+                        low=sizeof(int)*8-1;
+                bn_limit_bits_low=low;
+                bn_limit_num_low=1<<low;
+                }
+        if (mont >= 0)
+                {
+                if (mont > (sizeof(int)*8)-1)
+                        mont=sizeof(int)*8-1;
+                bn_limit_bits_mont=mont;
+                bn_limit_num_mont=1<<mont;
+                }
+        }
 
-BIGNUM *BN_value_one()
+int BN_get_params(int which)
+        {
+        if      (which == 0) return(bn_limit_bits);
+        else if (which == 1) return(bn_limit_bits_high);
+        else if (which == 2) return(bn_limit_bits_low);
+        else if (which == 3) return(bn_limit_bits_mont);
+        else return(0);
+        }
+
+BIGNUM *BN_value_one(void)
         {
         static BN_ULONG data_one=1L;
         static BIGNUM const_one={&data_one,1,1,0};
@@ -70,7 +129,7 @@ BIGNUM *BN_value_one()
         return(&const_one);
         }
 
-char *BN_options()
+char *BN_options(void)
         {
         static int init=0;
         static char data[16];
@@ -89,10 +148,9 @@ char *BN_options()
         return(data);
         }
 
-int BN_num_bits_word(l)
-BN_ULONG l;
+int BN_num_bits_word(BN_ULONG l)
         {
-        static char bits[256]={
+        static const char bits[256]={
                 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,
                 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
                 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
@@ -111,24 +169,24 @@ BN_ULONG l;
                 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
                 };
 
-#ifdef SIXTY_FOUR_BIT_LONG
+#if defined(SIXTY_FOUR_BIT_LONG)
         if (l & 0xffffffff00000000L)
                 {
                 if (l & 0xffff000000000000L)
                         {
                         if (l & 0xff00000000000000L)
                                 {
-                                return(bits[l>>56]+56);
+                                return(bits[(int)(l>>56)]+56);
                                 }
-                        else    return(bits[l>>48]+48);
+                        else    return(bits[(int)(l>>48)]+48);
                         }
                 else
                         {
                         if (l & 0x0000ff0000000000L)
                                 {
-                                return(bits[l>>40]+40);
+                                return(bits[(int)(l>>40)]+40);
                                 }
-                        else    return(bits[l>>32]+32);
+                        else    return(bits[(int)(l>>32)]+32);
                         }
                 }
         else
@@ -140,17 +198,17 @@ BN_ULONG l;
                         {
                         if (l & 0xff00000000000000LL)
                                 {
-                                return(bits[l>>56]+56);
+                                return(bits[(int)(l>>56)]+56);
                                 }
-                        else    return(bits[l>>48]+48);
+                        else    return(bits[(int)(l>>48)]+48);
                         }
                 else
                         {
                         if (l & 0x0000ff0000000000LL)
                                 {
-                                return(bits[l>>40]+40);
+                                return(bits[(int)(l>>40)]+40);
                                 }
-                        else    return(bits[l>>32]+32);
+                        else    return(bits[(int)(l>>32)]+32);
                         }
                 }
         else
@@ -161,28 +219,29 @@ BN_ULONG l;
                 if (l & 0xffff0000L)
                         {
                         if (l & 0xff000000L)
-                                return(bits[l>>24L]+24);
-                        else    return(bits[l>>16L]+16);
+                                return(bits[(int)(l>>24L)]+24);
+                        else    return(bits[(int)(l>>16L)]+16);
                         }
                 else
 #endif
                         {
 #if defined(SIXTEEN_BIT) || defined(THIRTY_TWO_BIT) || defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG)
                         if (l & 0xff00L)
-                                return(bits[l>>8]+8);
+                                return(bits[(int)(l>>8)]+8);
                         else    
 #endif
-                                return(bits[l   ]  );
+                                return(bits[(int)(l   )]  );
                         }
                 }
         }
 
-int BN_num_bits(a)
-BIGNUM *a;
+int BN_num_bits(const BIGNUM *a)
         {
         BN_ULONG l;
         int i;
 
+        bn_check_top(a);
+
         if (a->top == 0) return(0);
         l=a->d[a->top-1];
         i=(a->top-1)*BN_BITS2;
@@ -196,126 +255,256 @@ BIGNUM *a;
         return(i+BN_num_bits_word(l));
         }
 
-void BN_clear_free(a)
-BIGNUM *a;
+void BN_clear_free(BIGNUM *a)
         {
+        int i;
+
         if (a == NULL) return;
         if (a->d != NULL)
                 {
                 memset(a->d,0,a->max*sizeof(a->d[0]));
-                Free(a->d);
+                if (!(BN_get_flags(a,BN_FLG_STATIC_DATA)))
+                        Free(a->d);
                 }
+        i=BN_get_flags(a,BN_FLG_MALLOCED);
         memset(a,0,sizeof(BIGNUM));
-        Free(a);
+        if (i)
+                Free(a);
         }
 
-void BN_free(a)
-BIGNUM *a;
+void BN_free(BIGNUM *a)
         {
         if (a == NULL) return;
-        if (a->d != NULL) Free(a->d);
-        Free(a);
+        if ((a->d != NULL) && !(BN_get_flags(a,BN_FLG_STATIC_DATA)))
+                Free(a->d);
+        a->flags|=BN_FLG_FREE; /* REMOVE? */
+        if (a->flags & BN_FLG_MALLOCED)
+                Free(a);
+        }
+
+void BN_init(BIGNUM *a)
+        {
+        memset(a,0,sizeof(BIGNUM));
         }
 
-BIGNUM *BN_new()
+BIGNUM *BN_new(void)
         {
         BIGNUM *ret;
-        BN_ULONG *p;
 
-        ret=(BIGNUM *)Malloc(sizeof(BIGNUM));
-        if (ret == NULL) goto err;
+        if ((ret=(BIGNUM *)Malloc(sizeof(BIGNUM))) == NULL)
+                {
+                BNerr(BN_F_BN_NEW,ERR_R_MALLOC_FAILURE);
+                return(NULL);
+                }
+        ret->flags=BN_FLG_MALLOCED;
         ret->top=0;
         ret->neg=0;
-        ret->max=(BN_DEFAULT_BITS/BN_BITS2);
-        p=(BN_ULONG *)Malloc(sizeof(BN_ULONG)*(ret->max+1));
-        if (p == NULL) goto err;
-        ret->d=p;
-
-        memset(p,0,(ret->max+1)*sizeof(p[0]));
+        ret->max=0;
+        ret->d=NULL;
         return(ret);
-err:
-        BNerr(BN_F_BN_NEW,ERR_R_MALLOC_FAILURE);
-        return(NULL);
         }
 
-BN_CTX *BN_CTX_new()
+
+BN_CTX *BN_CTX_new(void)
         {
         BN_CTX *ret;
-        BIGNUM *n;
-        int i,j;
 
         ret=(BN_CTX *)Malloc(sizeof(BN_CTX));
-        if (ret == NULL) goto err2;
-
-        for (i=0; i<BN_CTX_NUM; i++)
+        if (ret == NULL)
                 {
-                n=BN_new();
-                if (n == NULL) goto err;
-                ret->bn[i]=n;
+                BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
+                return(NULL);
                 }
 
-        /* There is actually an extra one, this is for debugging my
-         * stuff */
-        ret->bn[BN_CTX_NUM]=NULL;
-
-        ret->tos=0;
+        BN_CTX_init(ret);
+        ret->flags=BN_FLG_MALLOCED;
         return(ret);
-err:
-        for (j=0; j<i; j++)
-                BN_free(ret->bn[j]);
-        Free(ret);
-err2:
-        BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
-        return(NULL);
         }
 
-void BN_CTX_free(c)
-BN_CTX *c;
+void BN_CTX_init(BN_CTX *ctx)
+        {
+        memset(ctx,0,sizeof(BN_CTX));
+        ctx->tos=0;
+        ctx->flags=0;
+        }
+
+void BN_CTX_free(BN_CTX *c)
         {
         int i;
 
+        if(c == NULL)
+            return;
+
         for (i=0; i<BN_CTX_NUM; i++)
-                BN_clear_free(c->bn[i]);
-        Free(c);
+                BN_clear_free(&(c->bn[i]));
+        if (c->flags & BN_FLG_MALLOCED)
+                Free(c);
         }
 
-BIGNUM *bn_expand2(b, words)
-BIGNUM *b;
-int words;
+BIGNUM *bn_expand2(BIGNUM *b, int words)
         {
-        BN_ULONG *p;
+        BN_ULONG *A,*a;
+        const BN_ULONG *B;
+        int i;
+
+        bn_check_top(b);
 
         if (words > b->max)
                 {
-                p=(BN_ULONG *)Realloc(b->d,sizeof(BN_ULONG)*(words+1));
-                if (p == NULL)
+                bn_check_top(b);        
+                if (BN_get_flags(b,BN_FLG_STATIC_DATA))
+                        {
+                        BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
+                        return(NULL);
+                        }
+                a=A=(BN_ULONG *)Malloc(sizeof(BN_ULONG)*(words+1));
+                if (A == NULL)
                         {
                         BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE);
                         return(NULL);
                         }
-                b->d=p;
-                memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG));
+#if 1
+                B=b->d;
+                /* Check if the previous number needs to be copied */
+                if (B != NULL)
+                        {
+#if 0
+                        /* This lot is an unrolled loop to copy b->top 
+                         * BN_ULONGs from B to A
+                         */
+/*
+ * I have nothing against unrolling but it's usually done for
+ * several reasons, namely:
+ * - minimize percentage of decision making code, i.e. branches;
+ * - avoid cache trashing;
+ * - make it possible to schedule loads earlier;
+ * Now let's examine the code below. The cornerstone of C is
+ * "programmer is always right" and that's what we love it for:-)
+ * For this very reason C compilers have to be paranoid when it
+ * comes to data aliasing and assume the worst. Yeah, but what
+ * does it mean in real life? This means that loop body below will
+ * be compiled to sequence of loads immediately followed by stores
+ * as compiler assumes the worst, something in A==B+1 style. As a
+ * result CPU pipeline is going to starve for incoming data. Secondly
+ * if A and B happen to share same cache line such code is going to
+ * cause severe cache trashing. Both factors have severe impact on
+ * performance of modern CPUs and this is the reason why this
+ * particulare piece of code is #ifdefed away and replaced by more
+ * "friendly" version found in #else section below. This comment
+ * also applies to BN_copy function.
+ *
+ *                                      <appro@fy.chalmers.se>
+ */
+                        for (i=b->top&(~7); i>0; i-=8)
+                                {
+                                A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
+                                A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7];
+                                A+=8;
+                                B+=8;
+                                }
+                        switch (b->top&7)
+                                {
+                        case 7:
+                                A[6]=B[6];
+                        case 6:
+                                A[5]=B[5];
+                        case 5:
+                                A[4]=B[4];
+                        case 4:
+                                A[3]=B[3];
+                        case 3:
+                                A[2]=B[2];
+                        case 2:
+                                A[1]=B[1];
+                        case 1:
+                                A[0]=B[0];
+                        case 0:
+                                /* I need the 'case 0' entry for utrix cc.
+                                 * If the optimiser is turned on, it does the
+                                 * switch table by doing
+                                 * a=top&7
+                                 * a--;
+                                 * goto jump_table[a];
+                                 * If top is 0, this makes us jump to 0xffffffc 
+                                 * which is rather bad :-(.
+                                 * eric 23-Apr-1998
+                                 */
+                                ;
+                                }
+#else
+                        for (i=b->top>>2; i>0; i--,A+=4,B+=4)
+                                {
+                                /*
+                                 * The fact that the loop is unrolled
+                                 * 4-wise is a tribute to Intel. It's
+                                 * the one that doesn't have enough
+                                 * registers to accomodate more data.
+                                 * I'd unroll it 8-wise otherwise:-)
+                                 *
+                                 *              <appro@fy.chalmers.se>
+                                 */
+                                BN_ULONG a0,a1,a2,a3;
+                                a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
+                                A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
+                                }
+                        switch (b->top&3)
+                                {
+                                case 3: A[2]=B[2];
+                                case 2: A[1]=B[1];
+                                case 1: A[0]=B[0];
+                                case 0: ; /* ultrix cc workaround, see above */
+                                }
+#endif
+                        Free(b->d);
+                        }
+
+                b->d=a;
                 b->max=words;
+
+                /* Now need to zero any data between b->top and b->max */
+
+                A= &(b->d[b->top]);
+                for (i=(b->max - b->top)>>3; i>0; i--,A+=8)
+                        {
+                        A[0]=0; A[1]=0; A[2]=0; A[3]=0;
+                        A[4]=0; A[5]=0; A[6]=0; A[7]=0;
+                        }
+                for (i=(b->max - b->top)&7; i>0; i--,A++)
+                        A[0]=0;
+#else
+                        memset(A,0,sizeof(BN_ULONG)*(words+1));
+                        memcpy(A,b->d,sizeof(b->d[0])*b->top);
+                        b->d=a;
+                        b->max=words;
+#endif
+                
+/*              memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */
+/*      { int i; for (i=b->max; i<words+1; i++) p[i]=i;} */
+
                 }
         return(b);
         }
 
-BIGNUM *BN_dup(a)
-BIGNUM *a;
+BIGNUM *BN_dup(const BIGNUM *a)
         {
         BIGNUM *r;
 
+        if (a == NULL) return NULL;
+
+        bn_check_top(a);
+
         r=BN_new();
         if (r == NULL) return(NULL);
         return((BIGNUM *)BN_copy(r,a));
         }
 
-BIGNUM *BN_copy(a, b)
-BIGNUM *a;
-BIGNUM *b;
+BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
         {
         int i;
-        BN_ULONG *A,*B;
+        BN_ULONG *A;
+        const BN_ULONG *B;
+
+        bn_check_top(b);
 
         if (a == b) return(a);
         if (bn_wexpand(a,b->top) == NULL) return(NULL);
@@ -323,35 +512,18 @@ BIGNUM *b;
 #if 1
         A=a->d;
         B=b->d;
-        for (i=b->top&(~7); i>0; i-=8)
+        for (i=b->top>>2; i>0; i--,A+=4,B+=4)
                 {
-                A[0]=B[0];
-                A[1]=B[1];
-                A[2]=B[2];
-                A[3]=B[3];
-                A[4]=B[4];
-                A[5]=B[5];
-                A[6]=B[6];
-                A[7]=B[7];
-                A+=8;
-                B+=8;
+                BN_ULONG a0,a1,a2,a3;
+                a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
+                A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
                 }
-        switch (b->top&7)
+        switch (b->top&3)
                 {
-        case 7:
-                A[6]=B[6];
-        case 6:
-                A[5]=B[5];
-        case 5:
-                A[4]=B[4];
-        case 4:
-                A[3]=B[3];
-        case 3:
-                A[2]=B[2];
-        case 2:
-                A[1]=B[1];
-        case 1:
-                A[0]=B[0];
+                case 3: A[2]=B[2];
+                case 2: A[1]=B[1];
+                case 1: A[0]=B[0];
+                case 0: ; /* ultrix cc workaround, see comments in bn_expand2 */
                 }
 #else
         memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
@@ -359,52 +531,47 @@ BIGNUM *b;
 
 /*      memset(&(a->d[b->top]),0,sizeof(a->d[0])*(a->max-b->top));*/
         a->top=b->top;
-        if (a->top == 0)
+        if ((a->top == 0) && (a->d != NULL))
                 a->d[0]=0;
         a->neg=b->neg;
         return(a);
         }
 
-void BN_clear(a)
-BIGNUM *a;
+void BN_clear(BIGNUM *a)
         {
-        memset(a->d,0,a->max*sizeof(a->d[0]));
+        if (a->d != NULL)
+                memset(a->d,0,a->max*sizeof(a->d[0]));
         a->top=0;
         a->neg=0;
         }
 
-unsigned long BN_get_word(a)
-BIGNUM *a;
+BN_ULONG BN_get_word(BIGNUM *a)
         {
         int i,n;
-        unsigned long ret=0;
+        BN_ULONG ret=0;
 
         n=BN_num_bytes(a);
-        if (n > sizeof(unsigned long))
-#ifdef SIXTY_FOUR_BIT_LONG
+        if (n > sizeof(BN_ULONG))
                 return(BN_MASK2);
-#else
-                return(0xFFFFFFFFL);
-#endif
         for (i=a->top-1; i>=0; i--)
                 {
 #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
                 ret<<=BN_BITS4; /* stops the compiler complaining */
                 ret<<=BN_BITS4;
+#else
+                ret=0;
 #endif
                 ret|=a->d[i];
                 }
         return(ret);
         }
 
-int BN_set_word(a,w)
-BIGNUM *a;
-unsigned long w;
+int BN_set_word(BIGNUM *a, BN_ULONG w)
         {
         int i,n;
-        if (bn_expand(a,sizeof(unsigned long)*8) == NULL) return(0);
+        if (bn_expand(a,sizeof(BN_ULONG)*8) == NULL) return(0);
 
-        n=sizeof(unsigned long)/BN_BYTES;
+        n=sizeof(BN_ULONG)/BN_BYTES;
         a->neg=0;
         a->top=0;
         a->d[0]=(BN_ULONG)w&BN_MASK2;
@@ -417,6 +584,8 @@ unsigned long w;
 #ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
                 w>>=BN_BITS4;
                 w>>=BN_BITS4;
+#else
+                w=0;
 #endif
                 a->d[i]=(BN_ULONG)w&BN_MASK2;
                 if (a->d[i] != 0) a->top=i+1;
@@ -425,10 +594,7 @@ unsigned long w;
         }
 
 /* ignore negative */
-BIGNUM *BN_bin2bn(s, len, ret)
-unsigned char *s;
-int len;
-BIGNUM *ret;
+BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
         {
         unsigned int i,m;
         unsigned int n;
@@ -465,9 +631,7 @@ BIGNUM *ret;
         }
 
 /* ignore negative */
-int BN_bn2bin(a, to)
-BIGNUM *a;
-unsigned char *to;
+int BN_bn2bin(const BIGNUM *a, unsigned char *to)
         {
         int n,i;
         BN_ULONG l;
@@ -481,13 +645,14 @@ unsigned char *to;
         return(n);
         }
 
-int BN_ucmp(a, b)
-BIGNUM *a;
-BIGNUM *b;
+int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
         {
         int i;
         BN_ULONG t1,t2,*ap,*bp;
 
+        bn_check_top(a);
+        bn_check_top(b);
+
         i=a->top-b->top;
         if (i != 0) return(i);
         ap=a->d;
@@ -502,9 +667,7 @@ BIGNUM *b;
         return(0);
         }
 
-int BN_cmp(a, b)
-BIGNUM *a;
-BIGNUM *b;
+int BN_cmp(const BIGNUM *a, const BIGNUM *b)
         {
         int i;
         int gt,lt;
@@ -519,6 +682,10 @@ BIGNUM *b;
                 else
                         return(0);
                 }
+
+        bn_check_top(a);
+        bn_check_top(b);
+
         if (a->neg != b->neg)
                 {
                 if (a->neg)
@@ -541,27 +708,25 @@ BIGNUM *b;
         return(0);
         }
 
-int BN_set_bit(a, n)
-BIGNUM *a;
-int n;
+int BN_set_bit(BIGNUM *a, int n)
         {
-        int i,j;
+        int i,j,k;
 
         i=n/BN_BITS2;
         j=n%BN_BITS2;
         if (a->top <= i)
                 {
-                if (bn_expand(a,n) == NULL) return(0);
+                if (bn_wexpand(a,i+1) == NULL) return(0);
+                for(k=a->top; k<i+1; k++)
+                        a->d[k]=0;
                 a->top=i+1;
                 }
 
-        a->d[i]|=(1L<<j);
+        a->d[i]|=(((BN_ULONG)1)<<j);
         return(1);
         }
 
-int BN_clear_bit(a, n)
-BIGNUM *a;
-int n;
+int BN_clear_bit(BIGNUM *a, int n)
         {
         int i,j;
 
@@ -569,13 +734,12 @@ int n;
         j=n%BN_BITS2;
         if (a->top <= i) return(0);
 
-        a->d[i]&=(~(1L<<j));
+        a->d[i]&=(~(((BN_ULONG)1)<<j));
+        bn_fix_top(a);
         return(1);
         }
 
-int BN_is_bit_set(a, n)
-BIGNUM *a;
-int n;
+int BN_is_bit_set(const BIGNUM *a, int n)
         {
         int i,j;
 
@@ -586,9 +750,7 @@ int n;
         return((a->d[i]&(((BN_ULONG)1)<<j))?1:0);
         }
 
-int BN_mask_bits(a,n)
-BIGNUM *a;
-int n;
+int BN_mask_bits(BIGNUM *a, int n)
         {
         int b,w;
 
@@ -601,11 +763,25 @@ int n;
                 {
                 a->top=w+1;
                 a->d[w]&= ~(BN_MASK2<<b);
-                while ((w >= 0) && (a->d[w] == 0))
-                        {
-                        a->top--;
-                        w--;
-                        }
                 }
+        bn_fix_top(a);
         return(1);
         }
+
+int bn_cmp_words(BN_ULONG *a, BN_ULONG *b, int n)
+        {
+        int i;
+        BN_ULONG aa,bb;
+
+        aa=a[n-1];
+        bb=b[n-1];
+        if (aa != bb) return((aa > bb)?1:-1);
+        for (i=n-2; i>=0; i--)
+                {
+                aa=a[i];
+                bb=b[i];
+                if (aa != bb) return((aa > bb)?1:-1);
+                }
+        return(0);
+        }
+