src/parsec/disk-image/parsec/parsec-benchmark/pkgs/libs/ssl/src/crypto/bn/bn_exp2.c - public/gem5-resources - Git at Google

 /* crypto/bn/bn_exp2.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.]
  */
 /* ====================================================================
  * Copyright (c) 1998-2000 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
  * are met:
  *
  * 1. Redistributions of source code must retain the above 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 acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    openssl-core@openssl.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED 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 OpenSSL PROJECT OR
  * ITS 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.
  * ====================================================================
  *
  * This product includes cryptographic software written by Eric Young
  * (eay@cryptsoft.com).  This product includes software written by Tim
  * Hudson (tjh@cryptsoft.com).
  *
  */

 #include <stdio.h>
 #include "cryptlib.h"
 #include "bn_lcl.h"

 #define TABLE_SIZE	32

 int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 	const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
 	BN_CTX *ctx, BN_MONT_CTX *in_mont)
 	{
 	int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
 	int r_is_one=1;
 	BIGNUM *d,*r;
 	const BIGNUM *a_mod_m;
 	/* Tables of variables obtained from 'ctx' */
 	BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
 	BN_MONT_CTX *mont=NULL;

 	bn_check_top(a1);
 	bn_check_top(p1);
 	bn_check_top(a2);
 	bn_check_top(p2);
 	bn_check_top(m);

 	if (!(m->d[0] & 1))
 		{
 		BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
 		return(0);
 		}
 	bits1=BN_num_bits(p1);
 	bits2=BN_num_bits(p2);
 	if ((bits1 == 0) && (bits2 == 0))
 		{
 		ret = BN_one(rr);
 		return ret;
 		}

 	bits=(bits1 > bits2)?bits1:bits2;

 	BN_CTX_start(ctx);
 	d = BN_CTX_get(ctx);
 	r = BN_CTX_get(ctx);
 	val1[0] = BN_CTX_get(ctx);
 	val2[0] = BN_CTX_get(ctx);
 	if(!d || !r || !val1[0] || !val2[0]) goto err;

 	if (in_mont != NULL)
 		mont=in_mont;
 	else
 		{
 		if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
 		if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
 		}

 	window1 = BN_window_bits_for_exponent_size(bits1);
 	window2 = BN_window_bits_for_exponent_size(bits2);

 	/*
 	 * Build table for a1:   val1[i] := a1^(2*i + 1) mod m  for i = 0 .. 2^(window1-1)
 	 */
 	if (a1->neg || BN_ucmp(a1,m) >= 0)
 		{
 		if (!BN_mod(val1[0],a1,m,ctx))
 			goto err;
 		a_mod_m = val1[0];
 		}
 	else
 		a_mod_m = a1;
 	if (BN_is_zero(a_mod_m))
 		{
 		BN_zero(rr);
 		ret = 1;
 		goto err;
 		}

 	if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err;
 	if (window1 > 1)
 		{
 		if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err;

 		j=1<<(window1-1);
 		for (i=1; i<j; i++)
 			{
 			if(((val1[i] = BN_CTX_get(ctx)) == NULL) ||
 					!BN_mod_mul_montgomery(val1[i],val1[i-1],
 						d,mont,ctx))
 				goto err;
 			}
 		}


 	/*
 	 * Build table for a2:   val2[i] := a2^(2*i + 1) mod m  for i = 0 .. 2^(window2-1)
 	 */
 	if (a2->neg || BN_ucmp(a2,m) >= 0)
 		{
 		if (!BN_mod(val2[0],a2,m,ctx))
 			goto err;
 		a_mod_m = val2[0];
 		}
 	else
 		a_mod_m = a2;
 	if (BN_is_zero(a_mod_m))
 		{
 		BN_zero(rr);
 		ret = 1;
 		goto err;
 		}
 	if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err;
 	if (window2 > 1)
 		{
 		if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err;

 		j=1<<(window2-1);
 		for (i=1; i<j; i++)
 			{
 			if(((val2[i] = BN_CTX_get(ctx)) == NULL) ||
 					!BN_mod_mul_montgomery(val2[i],val2[i-1],
 						d,mont,ctx))
 				goto err;
 			}
 		}


 	/* Now compute the power product, using independent windows. */
 	r_is_one=1;
 	wvalue1=0;  /* The 'value' of the first window */
 	wvalue2=0;  /* The 'value' of the second window */
 	wpos1=0;    /* If wvalue1 > 0, the bottom bit of the first window */
 	wpos2=0;    /* If wvalue2 > 0, the bottom bit of the second window */

 	if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
 	for (b=bits-1; b>=0; b--)
 		{
 		if (!r_is_one)
 			{
 			if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
 				goto err;
 			}

 		if (!wvalue1)
 			if (BN_is_bit_set(p1, b))
 				{
 				/* consider bits b-window1+1 .. b for this window */
 				i = b-window1+1;
 				while (!BN_is_bit_set(p1, i)) /* works for i<0 */
 					i++;
 				wpos1 = i;
 				wvalue1 = 1;
 				for (i = b-1; i >= wpos1; i--)
 					{
 					wvalue1 <<= 1;
 					if (BN_is_bit_set(p1, i))
 						wvalue1++;
 					}
 				}

 		if (!wvalue2)
 			if (BN_is_bit_set(p2, b))
 				{
 				/* consider bits b-window2+1 .. b for this window */
 				i = b-window2+1;
 				while (!BN_is_bit_set(p2, i))
 					i++;
 				wpos2 = i;
 				wvalue2 = 1;
 				for (i = b-1; i >= wpos2; i--)
 					{
 					wvalue2 <<= 1;
 					if (BN_is_bit_set(p2, i))
 						wvalue2++;
 					}
 				}

 		if (wvalue1 && b == wpos1)
 			{
 			/* wvalue1 is odd and < 2^window1 */
 			if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx))
 				goto err;
 			wvalue1 = 0;
 			r_is_one = 0;
 			}

 		if (wvalue2 && b == wpos2)
 			{
 			/* wvalue2 is odd and < 2^window2 */
 			if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx))
 				goto err;
 			wvalue2 = 0;
 			r_is_one = 0;
 			}
 		}
 	BN_from_montgomery(rr,r,mont,ctx);
 	ret=1;
 err:
 	if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
 	BN_CTX_end(ctx);
 	bn_check_top(rr);
 	return(ret);
 	}
	/* crypto/bn/bn_exp2.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.]
	*/
	/* ====================================================================
	* Copyright (c) 1998-2000 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
	* are met:
	*
	* 1. Redistributions of source code must retain the above 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 acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* openssl-core@openssl.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED 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 OpenSSL PROJECT OR
	* ITS 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.
	* ====================================================================
	*
	* This product includes cryptographic software written by Eric Young
	* (eay@cryptsoft.com). This product includes software written by Tim
	* Hudson (tjh@cryptsoft.com).
	*
	*/

	#include <stdio.h>
	#include "cryptlib.h"
	#include "bn_lcl.h"

	#define TABLE_SIZE 32

	int BN_mod_exp2_mont(BIGNUM rr, const BIGNUM a1, const BIGNUM *p1,
	const BIGNUM a2, const BIGNUM p2, const BIGNUM *m,
	BN_CTX ctx, BN_MONT_CTX in_mont)
	{
	int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
	int r_is_one=1;
	BIGNUM d,r;
	const BIGNUM *a_mod_m;
	/* Tables of variables obtained from 'ctx' */
	BIGNUM val1[TABLE_SIZE], val2[TABLE_SIZE];
	BN_MONT_CTX *mont=NULL;

	bn_check_top(a1);
	bn_check_top(p1);
	bn_check_top(a2);
	bn_check_top(p2);
	bn_check_top(m);

	if (!(m->d[0] & 1))
	{
	BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
	return(0);
	}
	bits1=BN_num_bits(p1);
	bits2=BN_num_bits(p2);
	if ((bits1 == 0) && (bits2 == 0))
	{
	ret = BN_one(rr);
	return ret;
	}

	bits=(bits1 > bits2)?bits1:bits2;

	BN_CTX_start(ctx);
	d = BN_CTX_get(ctx);
	r = BN_CTX_get(ctx);
	val1[0] = BN_CTX_get(ctx);
	val2[0] = BN_CTX_get(ctx);
	if(!d \|\| !r \|\| !val1[0] \|\| !val2[0]) goto err;

	if (in_mont != NULL)
	mont=in_mont;
	else
	{
	if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
	if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
	}

	window1 = BN_window_bits_for_exponent_size(bits1);
	window2 = BN_window_bits_for_exponent_size(bits2);

	/*
	* Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
	*/
	if (a1->neg \|\| BN_ucmp(a1,m) >= 0)
	{
	if (!BN_mod(val1[0],a1,m,ctx))
	goto err;
	a_mod_m = val1[0];
	}
	else
	a_mod_m = a1;
	if (BN_is_zero(a_mod_m))
	{
	BN_zero(rr);
	ret = 1;
	goto err;
	}

	if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err;
	if (window1 > 1)
	{
	if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err;

	j=1<<(window1-1);
	for (i=1; i<j; i++)
	{
	if(((val1[i] = BN_CTX_get(ctx)) == NULL) \|\|
	!BN_mod_mul_montgomery(val1[i],val1[i-1],
	d,mont,ctx))
	goto err;
	}
	}


	/*
	* Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
	*/
	if (a2->neg \|\| BN_ucmp(a2,m) >= 0)
	{
	if (!BN_mod(val2[0],a2,m,ctx))
	goto err;
	a_mod_m = val2[0];
	}
	else
	a_mod_m = a2;
	if (BN_is_zero(a_mod_m))
	{
	BN_zero(rr);
	ret = 1;
	goto err;
	}
	if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err;
	if (window2 > 1)
	{
	if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err;

	j=1<<(window2-1);
	for (i=1; i<j; i++)
	{
	if(((val2[i] = BN_CTX_get(ctx)) == NULL) \|\|
	!BN_mod_mul_montgomery(val2[i],val2[i-1],
	d,mont,ctx))
	goto err;
	}
	}


	/* Now compute the power product, using independent windows. */
	r_is_one=1;
	wvalue1=0; /* The 'value' of the first window */
	wvalue2=0; /* The 'value' of the second window */
	wpos1=0; /* If wvalue1 > 0, the bottom bit of the first window */
	wpos2=0; /* If wvalue2 > 0, the bottom bit of the second window */

	if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
	for (b=bits-1; b>=0; b--)
	{
	if (!r_is_one)
	{
	if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
	goto err;
	}

	if (!wvalue1)
	if (BN_is_bit_set(p1, b))
	{
	/* consider bits b-window1+1 .. b for this window */
	i = b-window1+1;
	while (!BN_is_bit_set(p1, i)) /* works for i<0 */
	i++;
	wpos1 = i;
	wvalue1 = 1;
	for (i = b-1; i >= wpos1; i--)
	{
	wvalue1 <<= 1;
	if (BN_is_bit_set(p1, i))
	wvalue1++;
	}
	}

	if (!wvalue2)
	if (BN_is_bit_set(p2, b))
	{
	/* consider bits b-window2+1 .. b for this window */
	i = b-window2+1;
	while (!BN_is_bit_set(p2, i))
	i++;
	wpos2 = i;
	wvalue2 = 1;
	for (i = b-1; i >= wpos2; i--)
	{
	wvalue2 <<= 1;
	if (BN_is_bit_set(p2, i))
	wvalue2++;
	}
	}

	if (wvalue1 && b == wpos1)
	{
	/* wvalue1 is odd and < 2^window1 */
	if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx))
	goto err;
	wvalue1 = 0;
	r_is_one = 0;
	}

	if (wvalue2 && b == wpos2)
	{
	/* wvalue2 is odd and < 2^window2 */
	if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx))
	goto err;
	wvalue2 = 0;
	r_is_one = 0;
	}
	}
	BN_from_montgomery(rr,r,mont,ctx);
	ret=1;
	err:
	if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
	BN_CTX_end(ctx);
	bn_check_top(rr);
	return(ret);
	}