/* crypto/bn/bn_shift.c */

 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

  * All rights reserved.

  *

  * This package is an SSL implementation written

  * by Eric Young (eay@cryptsoft.com).

  * The implementation was written so as to conform with Netscapes SSL.

  * 

  * This library is free for commercial and non-commercial use as long as

  * the following conditions are aheared to.  The following conditions

  * apply to all code found in this distribution, be it the RC4, RSA,

  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

  * included with this distribution is covered by the same copyright terms

  * except that the holder is Tim Hudson (tjh@cryptsoft.com).

  * 

  * Copyright remains Eric Young's, and as such any Copyright notices in

  * the code are not to be removed.

  * If this package is used in a product, Eric Young should be given attribution

  * as the author of the parts of the library used.

  * This can be in the form of a textual message at program startup or

  * in documentation (online or textual) provided with the package.

  * 

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  * 3. All advertising materials mentioning features or use of this software

  *    must display the following acknowledgement:

  *    "This product includes cryptographic software written by

  *     Eric Young (eay@cryptsoft.com)"

  *    The word 'cryptographic' can be left out if the rouines from the library

  *    being used are not cryptographic related :-).

  * 4. If you include any Windows specific code (or a derivative thereof) from 

  *    the apps directory (application code) you must include an acknowledgement:

  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

  * 

  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  * SUCH DAMAGE.

  * 

  * The licence and distribution terms for any publically available version or

  * derivative of this code cannot be changed.  i.e. this code cannot simply be

  * copied and put under another distribution licence

  * [including the GNU Public Licence.]

  */

 #include <stdio.h>

 #include "cryptlib.h"

 #include "bn_lcl.h"

 EXPORT_C 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_wexpand(r,a->top+1) == NULL) return(0);

 		r->top=a->top;

 		}

 	else

 		{

 		if (bn_wexpand(r,a->top+1) == NULL) return(0);

 		}

 	ap=a->d;

 	rp=r->d;

 	c=0;

 	for (i=0; i<a->top; i++)

 		{

 		t= *(ap++);

 		*(rp++)=((t<<1)|c)&BN_MASK2;

 		c=(t & BN_TBIT)?1:0;

 		}

 	if (c)

 		{

 		*rp=1;

 		r->top++;

 		}

 	bn_check_top(r);

 	return(1);

 	}

 EXPORT_C int BN_rshift1(BIGNUM *r, const BIGNUM *a)

 	{

 	BN_ULONG *ap,*rp,t,c;

 	int i;

 	bn_check_top(r);

 	bn_check_top(a);

 	if (BN_is_zero(a))

 		{

 		BN_zero(r);

 		return(1);

 		}

 	if (a != r)

 		{

 		if (bn_wexpand(r,a->top) == NULL) return(0);

 		r->top=a->top;

 		r->neg=a->neg;

 		}

 	ap=a->d;

 	rp=r->d;

 	c=0;

 	for (i=a->top-1; i>=0; i--)

 		{

 		t=ap[i];

 		rp[i]=((t>>1)&BN_MASK2)|c;

 		c=(t&1)?BN_TBIT:0;

 		}

 	bn_correct_top(r);

 	bn_check_top(r);

 	return(1);

 	}

 EXPORT_C 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;

 	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;

 	t=r->d;

 	t[a->top+nw]=0;

 	if (lb == 0)

 		for (i=a->top-1; i>=0; i--)

 			t[nw+i]=f[i];

 	else

 		for (i=a->top-1; i>=0; i--)

 			{

 			l=f[i];

 			t[nw+i+1]|=(l>>rb)&BN_MASK2;

 			t[nw+i]=(l<<lb)&BN_MASK2;

 			}

 	memset(t,0,nw*sizeof(t[0]));

 /*	for (i=0; i<nw; i++)

 		t[i]=0;*/

 	r->top=a->top+nw+1;

 	bn_correct_top(r);

 	bn_check_top(r);

 	return(1);

 	}

 EXPORT_C 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 || a->top == 0)

 		{

 		BN_zero(r);

 		return(1);

 		}

 	if (r != a)

 		{

 		r->neg=a->neg;

 		if (bn_wexpand(r,a->top-nw+1) == 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;

 	if (rb == 0)

 		{

 		for (i=j; i != 0; i--)

 			*(t++)= *(f++);

 		}

 	else

 		{

 		l= *(f++);

 		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;

 		}

 	bn_correct_top(r);

 	bn_check_top(r);

 	return(1);

 	}