/* crypto/bn/bn_shift.c */
-/* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
+/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* [including the GNU Public Licence.]
*/
-#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"
-int BN_lshift1(r, a)
-BIGNUM *r;
-BIGNUM *a;
+int BN_lshift1(BIGNUM *r, const BIGNUM *a)
{
register BN_ULONG *ap,*rp,t,c;
int i;
+ bn_check_top(r);
+ bn_check_top(a);
+
if (r != a)
{
r->neg=a->neg;
- if (bn_expand(r,(a->top+1)*BN_BITS2) == NULL) return(0);
+ if (bn_wexpand(r,a->top+1) == NULL) return(0);
r->top=a->top;
}
else
{
- if (bn_expand(r,(a->top+1)*BN_BITS2) == NULL) return(0);
+ if (bn_wexpand(r,a->top+1) == NULL) return(0);
}
ap=a->d;
rp=r->d;
*rp=1;
r->top++;
}
+ bn_check_top(r);
return(1);
}
-int BN_rshift1(r, a)
-BIGNUM *r;
-BIGNUM *a;
+int BN_rshift1(BIGNUM *r, const BIGNUM *a)
{
BN_ULONG *ap,*rp,t,c;
- int i;
+ int i,j;
+
+ bn_check_top(r);
+ bn_check_top(a);
if (BN_is_zero(a))
{
BN_zero(r);
return(1);
}
+ i = a->top;
+ ap= a->d;
+ j = i-(ap[i-1]==1);
if (a != r)
{
- if (bn_expand(r,a->top*BN_BITS2) == NULL) return(0);
- r->top=a->top;
+ if (bn_wexpand(r,j) == NULL) return(0);
r->neg=a->neg;
}
- ap=a->d;
rp=r->d;
- c=0;
- for (i=a->top-1; i>=0; i--)
+ t=ap[--i];
+ c=(t&1)?BN_TBIT:0;
+ if (t>>=1) rp[i]=t;
+ while (i>0)
{
- t=ap[i];
+ t=ap[--i];
rp[i]=((t>>1)&BN_MASK2)|c;
c=(t&1)?BN_TBIT:0;
}
- bn_fix_top(r);
+ r->top=j;
+ bn_check_top(r);
return(1);
}
-int BN_lshift(r, a, n)
-BIGNUM *r;
-BIGNUM *a;
-int n;
+int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
{
int i,nw,lb,rb;
BN_ULONG *t,*f;
BN_ULONG l;
+ bn_check_top(r);
+ bn_check_top(a);
+
r->neg=a->neg;
- if (bn_expand(r,(a->top*BN_BITS2)+n) == NULL) return(0);
nw=n/BN_BITS2;
+ if (bn_wexpand(r,a->top+nw+1) == NULL) return(0);
lb=n%BN_BITS2;
rb=BN_BITS2-lb;
f=a->d;
/* for (i=0; i<nw; i++)
t[i]=0;*/
r->top=a->top+nw+1;
- bn_fix_top(r);
+ bn_correct_top(r);
+ bn_check_top(r);
return(1);
}
-int BN_rshift(r, a, n)
-BIGNUM *r;
-BIGNUM *a;
-int n;
+int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
{
int i,j,nw,lb,rb;
BN_ULONG *t,*f;
BN_ULONG l,tmp;
+ bn_check_top(r);
+ bn_check_top(a);
+
nw=n/BN_BITS2;
rb=n%BN_BITS2;
lb=BN_BITS2-rb;
- if (nw > a->top)
+ if (nw >= a->top || a->top == 0)
{
BN_zero(r);
return(1);
}
+ i = (BN_num_bits(a)-n+(BN_BITS2-1))/BN_BITS2;
if (r != a)
{
r->neg=a->neg;
- if (bn_expand(r,(a->top-nw+1)*BN_BITS2) == NULL) return(0);
+ if (bn_wexpand(r,i) == NULL) return(0);
+ }
+ else
+ {
+ if (n == 0)
+ return 1; /* or the copying loop will go berserk */
}
f= &(a->d[nw]);
t=r->d;
j=a->top-nw;
- r->top=j;
+ r->top=i;
if (rb == 0)
{
- for (i=j+1; i > 0; i--)
+ for (i=j; i != 0; i--)
*(t++)= *(f++);
}
else
{
l= *(f++);
- for (i=1; i<j; i++)
+ for (i=j-1; i != 0; i--)
{
tmp =(l>>rb)&BN_MASK2;
l= *(f++);
*(t++) =(tmp|(l<<lb))&BN_MASK2;
}
- *(t++) =(l>>rb)&BN_MASK2;
+ if ((l = (l>>rb)&BN_MASK2)) *(t) = l;
}
- *t=0;
- bn_fix_top(r);
+ bn_check_top(r);
return(1);
}