GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcrypto/crypto/../../libssl/src/crypto/bn/bn_sqr.c Lines: 84 99 84.8 %
Date: 2016-12-06 Branches: 40 52 76.9 %

Line Branch Exec Source
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/* $OpenBSD: bn_sqr.c,v 1.12 2015/02/09 15:49:22 jsing Exp $ */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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 * All rights reserved.
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 *
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 * This package is an SSL implementation written
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 * by Eric Young (eay@cryptsoft.com).
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 * The implementation was written so as to conform with Netscapes SSL.
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 *
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 * This library is free for commercial and non-commercial use as long as
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 * the following conditions are aheared to.  The following conditions
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 * apply to all code found in this distribution, be it the RC4, RSA,
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 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
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 * included with this distribution is covered by the same copyright terms
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 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
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 *
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 * Copyright remains Eric Young's, and as such any Copyright notices in
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 * the code are not to be removed.
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 * If this package is used in a product, Eric Young should be given attribution
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 * as the author of the parts of the library used.
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 * This can be in the form of a textual message at program startup or
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 * in documentation (online or textual) provided with the package.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. All advertising materials mentioning features or use of this software
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 *    must display the following acknowledgement:
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 *    "This product includes cryptographic software written by
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 *     Eric Young (eay@cryptsoft.com)"
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 *    The word 'cryptographic' can be left out if the rouines from the library
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 *    being used are not cryptographic related :-).
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 * 4. If you include any Windows specific code (or a derivative thereof) from
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 *    the apps directory (application code) you must include an acknowledgement:
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 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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 *
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 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 *
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 * The licence and distribution terms for any publically available version or
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 * derivative of this code cannot be changed.  i.e. this code cannot simply be
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 * copied and put under another distribution licence
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 * [including the GNU Public Licence.]
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 */
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#include <stdio.h>
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#include <string.h>
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62
#include "bn_lcl.h"
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64
/* r must not be a */
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/* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96 */
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int
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BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
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378022
{
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	int max, al;
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378022
	int ret = 0;
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	BIGNUM *tmp, *rr;
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73
#ifdef BN_COUNT
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	fprintf(stderr, "BN_sqr %d * %d\n", a->top, a->top);
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#endif
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	bn_check_top(a);
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78
378022
	al = a->top;
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378022
	if (al <= 0) {
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94
		r->top = 0;
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94
		r->neg = 0;
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94
		return 1;
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	}
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85
377928
	BN_CTX_start(ctx);
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377928
	rr = (a != r) ? r : BN_CTX_get(ctx);
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377928
	tmp = BN_CTX_get(ctx);
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377928
	if (rr == NULL || tmp == NULL)
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		goto err;
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91
377928
	max = 2 * al; /* Non-zero (from above) */
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377928
	if (bn_wexpand(rr, max) == NULL)
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		goto err;
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95
377928
	if (al == 4) {
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#ifndef BN_SQR_COMBA
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		BN_ULONG t[8];
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		bn_sqr_normal(rr->d, a->d, 4, t);
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#else
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5959
		bn_sqr_comba4(rr->d, a->d);
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#endif
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371969
	} else if (al == 8) {
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#ifndef BN_SQR_COMBA
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		BN_ULONG t[16];
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		bn_sqr_normal(rr->d, a->d, 8, t);
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#else
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126084
		bn_sqr_comba8(rr->d, a->d);
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#endif
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	} else {
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#if defined(BN_RECURSION)
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245885
		if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
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			BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL*2];
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245874
			bn_sqr_normal(rr->d, a->d, al, t);
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		} else {
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			int j, k;
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117
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			j = BN_num_bits_word((BN_ULONG)al);
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11
			j = 1 << (j - 1);
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11
			k = j + j;
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11
			if (al == j) {
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10
				if (bn_wexpand(tmp, k * 2) == NULL)
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					goto err;
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				bn_sqr_recursive(rr->d, a->d, al, tmp->d);
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			} else {
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1
				if (bn_wexpand(tmp, max) == NULL)
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					goto err;
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1
				bn_sqr_normal(rr->d, a->d, al, tmp->d);
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			}
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		}
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#else
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		if (bn_wexpand(tmp, max) == NULL)
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			goto err;
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		bn_sqr_normal(rr->d, a->d, al, tmp->d);
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#endif
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	}
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377928
	rr->neg = 0;
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	/* If the most-significant half of the top word of 'a' is zero, then
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	 * the square of 'a' will max-1 words. */
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377928
	if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l))
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259262
		rr->top = max - 1;
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	else
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118666
		rr->top = max;
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377928
	if (rr != r)
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		BN_copy(r, rr);
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377928
	ret = 1;
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377928
err:
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	bn_check_top(rr);
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	bn_check_top(tmp);
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377928
	BN_CTX_end(ctx);
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377928
	return (ret);
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}
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/* tmp must have 2*n words */
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void
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bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
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245875
{
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	int i, j, max;
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	const BN_ULONG *ap;
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	BN_ULONG *rp;
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245875
	max = n * 2;
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245875
	ap = a;
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245875
	rp = r;
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245875
	rp[0] = rp[max - 1] = 0;
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245875
	rp++;
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245875
	j = n;
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170
245875
	if (--j > 0) {
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55127
		ap++;
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55127
		rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
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55127
		rp += 2;
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	}
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415045
	for (i = n - 2; i > 0; i--) {
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169170
		j--;
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169170
		ap++;
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169170
		rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
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169170
		rp += 2;
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	}
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245875
	bn_add_words(r, r, r, max);
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	/* There will not be a carry */
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245875
	bn_sqr_words(tmp, a, n);
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245875
	bn_add_words(r, r, tmp, max);
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245875
}
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#ifdef BN_RECURSION
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/* r is 2*n words in size,
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 * a and b are both n words in size.    (There's not actually a 'b' here ...)
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 * n must be a power of 2.
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 * We multiply and return the result.
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 * t must be 2*n words in size
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 * We calculate
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 * a[0]*b[0]
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 * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
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 * a[1]*b[1]
202
 */
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void
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bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
205
76
{
206
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	int n = n2 / 2;
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	int zero, c1;
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	BN_ULONG ln, lo, *p;
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210
#ifdef BN_COUNT
211
	fprintf(stderr, " bn_sqr_recursive %d * %d\n", n2, n2);
212
#endif
213
76
	if (n2 == 4) {
214
#ifndef BN_SQR_COMBA
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		bn_sqr_normal(r, a, 4, t);
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#else
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		bn_sqr_comba4(r, a);
218
#endif
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		return;
220
76
	} else if (n2 == 8) {
221
#ifndef BN_SQR_COMBA
222
		bn_sqr_normal(r, a, 8, t);
223
#else
224
54
		bn_sqr_comba8(r, a);
225
#endif
226
54
		return;
227
	}
228
22
	if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
229
		bn_sqr_normal(r, a, n2, t);
230
		return;
231
	}
232
	/* r=(a[0]-a[1])*(a[1]-a[0]) */
233
22
	c1 = bn_cmp_words(a, &(a[n]), n);
234
22
	zero = 0;
235
22
	if (c1 > 0)
236
17
		bn_sub_words(t, a, &(a[n]), n);
237
5
	else if (c1 < 0)
238
5
		bn_sub_words(t, &(a[n]), a, n);
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	else
240
		zero = 1;
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242
	/* The result will always be negative unless it is zero */
243
22
	p = &(t[n2*2]);
244
245
22
	if (!zero)
246
22
		bn_sqr_recursive(&(t[n2]), t, n, p);
247
	else
248
		memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
249
22
	bn_sqr_recursive(r, a, n, p);
250
22
	bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
251
252
	/* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
253
	 * r[10] holds (a[0]*b[0])
254
	 * r[32] holds (b[1]*b[1])
255
	 */
256
257
22
	c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
258
259
	/* t[32] is negative */
260
22
	c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
261
262
	/* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
263
	 * r[10] holds (a[0]*a[0])
264
	 * r[32] holds (a[1]*a[1])
265
	 * c1 holds the carry bits
266
	 */
267
22
	c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
268
22
	if (c1) {
269
8
		p = &(r[n + n2]);
270
8
		lo= *p;
271
8
		ln = (lo + c1) & BN_MASK2;
272
8
		*p = ln;
273
274
		/* The overflow will stop before we over write
275
		 * words we should not overwrite */
276
8
		if (ln < (BN_ULONG)c1) {
277
			do {
278
				p++;
279
				lo= *p;
280
				ln = (lo + 1) & BN_MASK2;
281
				*p = ln;
282
			} while (ln == 0);
283
		}
284
	}
285
}
286
#endif