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git-svn-id: file:///Users/lillianskinner/Downloads/platinum/twl/TwlIPL/trunk@72 b08762b0-b915-fc4b-9d8c-17b2551a87ff
321 lines
6.4 KiB
C
321 lines
6.4 KiB
C
/*---------------------------------------------------------------------------*
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Project: TwlIPL
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File:
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Copyright 2007 Nintendo. All rights reserved.
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These coded instructions, statements, and computer programs contain
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proprietary information of Nintendo of America Inc. and/or Nintendo
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Company Ltd., and are protected by Federal copyright law. They may
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not be disclosed to third parties or copied or duplicated in any form,
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in whole or in part, without the prior written consent of Nintendo.
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$Date:: $
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$Rev$
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$Author$
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*---------------------------------------------------------------------------*/
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/*
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* Copyright (C) 1998-2002 RSA Security Inc. All rights reserved.
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*
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* This work contains proprietary information of RSA Security.
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* Distribution is limited to authorized licensees of RSA
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* Security. Any unauthorized reproduction, distribution or
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* modification of this work is strictly prohibited.
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*
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*/
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/**
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* @file bn_add.c
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* @brief BIGNUM addition and subtraction functions
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*/
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#include "bn_lcl.h"
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#if !(defined(NO_SPLIT) && defined(SPLIT_FILE))
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#ifdef NO_SPLIT
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#define SPLIT_BN_ADD
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#define SPLIT_BN_UADD
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#define SPLIT_BN_USUB
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#define SPLIT_BN_SUB
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#endif /* NO_SPLIT */
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#ifdef SPLIT_BN_ADD
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/* r can == a or b */
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int BN_add(r, a, b)
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BIGNUM *r;
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BIGNUM *a;
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BIGNUM *b;
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{
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BIGNUM *tmp;
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bn_check_top(a);
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bn_check_top(b);
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/* a + b a+b
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* a + -b a-b
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* -a + b b-a
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* -a + -b -(a+b)
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*/
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if (a->neg ^ b->neg)
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{
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/* only one is negative */
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if (a->neg)
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{ tmp=a; a=b; b=tmp; }
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/* we are now a - b */
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if (BN_ucmp(a,b) < 0)
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{
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if (!BN_usub(r,b,a)) return(0);
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r->neg=1;
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}
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else
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{
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if (!BN_usub(r,a,b)) return(0);
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r->neg=0;
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}
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return(1);
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}
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if (a->neg) /* both are neg */
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r->neg=1;
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else
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r->neg=0;
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if (!BN_uadd(r,a,b)) return(0);
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return(1);
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}
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#endif
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#ifdef SPLIT_BN_UADD
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/* unsigned add of b to a, r must be large enough */
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int BN_uadd(r,a,b)
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BIGNUM *r;
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BIGNUM *a;
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BIGNUM *b;
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{
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register int i;
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int max,min;
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BN_ULONG *ap,*bp,*rp,carry,t1;
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BIGNUM *tmp;
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bn_check_top(a);
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bn_check_top(b);
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if (a->top < b->top)
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{ tmp=a; a=b; b=tmp; }
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max=a->top;
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min=b->top;
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if (bn_wexpand(r,max+1) == NULL)
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return(0);
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r->top=max;
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ap=a->d;
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bp=b->d;
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rp=r->d;
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carry=0;
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carry=bn_add_words(rp,ap,bp,min);
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rp+=min;
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ap+=min;
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bp+=min;
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i=min;
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if (carry)
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{
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while (i < max)
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{
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i++;
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t1= *(ap++);
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if ((*(rp++)=(t1+1)&BN_MASK2) >= t1)
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{
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carry=0;
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break;
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}
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}
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if ((i >= max) && carry)
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{
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*(rp++)=1;
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r->top++;
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}
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}
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if (rp != ap)
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{
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for (; i<max; i++)
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*(rp++)= *(ap++);
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}
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/* Memcpy(rp,ap,sizeof(*ap)*(max-i));*/
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return(1);
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}
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#endif
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/**
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* perform unsigned subtraction of <tt>b</tt> from <tt>a</tt>
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* @param r result of subtraction
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* @param a pointer to a BIGNUM
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* @param b pointer to a BIGNUM
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* @pre <tt>a</tt> must be larger than <tt>b</tt>
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* @return 1 on success, 0 on failure
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* @todo On next IRIX port check the validity of IRIX_CC_BUG.
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*/
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#ifdef SPLIT_BN_USUB
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int BN_usub(r, a, b)
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BIGNUM *r;
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BIGNUM *a;
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BIGNUM *b;
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{
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int max,min;
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register BN_ULONG t1,t2,*ap,*bp,*rp;
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int i,carry;
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#if defined(IRIX_CC_BUG) && !defined(LINT)
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int dummy;
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#endif
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bn_check_top(a);
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bn_check_top(b);
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/*
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* check for pre-condition violation
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*/
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if (a->top < b->top)
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{
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#ifndef NO_ERR
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BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3);
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#endif
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return(0);
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}
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max=a->top;
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min=b->top;
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if (bn_wexpand(r,max) == NULL) return(0);
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ap=a->d;
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bp=b->d;
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rp=r->d;
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/*
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* perform the subtraction and see if we
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* have a (final) carry
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*/
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carry=0;
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for (i=0; i<min; i++)
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{
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t1= *(ap++);
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t2= *(bp++);
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if (carry)
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{
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carry=(t1 <= t2);
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t1=(t1-t2-1)&BN_MASK2;
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}
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else
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{
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carry=(t1 < t2);
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t1=(t1-t2)&BN_MASK2;
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}
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#if defined(IRIX_CC_BUG) && !defined(LINT)
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dummy=t1;
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#endif
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*(rp++)=t1&BN_MASK2;
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}
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if (carry) /* subtracted */
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{
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while (i < max)
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{
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i++;
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t1= *(ap++);
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t2=(t1-1)&BN_MASK2;
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*(rp++)=t2;
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if (t1 > t2) break;
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}
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}
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if (rp != ap)
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{
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#ifdef BN_LIBRARY_SMALL
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Memcpy(rp,ap,sizeof(*rp)*(max-i));
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#else /* BN_LIBRARY_SMALL */
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for (;;)
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{
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if (i++ >= max) break;
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rp[0]=ap[0];
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if (i++ >= max) break;
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rp[1]=ap[1];
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if (i++ >= max) break;
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rp[2]=ap[2];
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if (i++ >= max) break;
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rp[3]=ap[3];
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rp+=4;
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ap+=4;
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}
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#endif /* BN_LIBRARY_SMALL */
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}
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r->top=max;
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bn_fix_top(r);
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return(1);
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}
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#endif
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#ifdef SPLIT_BN_SUB
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int BN_sub(r, a, b)
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BIGNUM *r;
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BIGNUM *a;
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BIGNUM *b;
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{
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int max;
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int add=0,neg=0;
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BIGNUM *tmp;
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bn_check_top(a);
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bn_check_top(b);
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/* a - b a-b
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* a - -b a+b
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* -a - b -(a+b)
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* -a - -b b-a
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*/
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if (a->neg)
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{
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if (b->neg)
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{ tmp=a; a=b; b=tmp; }
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else
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{ add=1; neg=1; }
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}
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else
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{
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if (b->neg) { add=1; neg=0; }
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}
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if (add)
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{
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if (!BN_uadd(r,a,b)) return(0);
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r->neg=neg;
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return(1);
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}
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/* We are actually doing a - b */
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max=(a->top > b->top)?a->top:b->top;
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if (bn_wexpand(r,max) == NULL) return(0);
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if (BN_ucmp(a,b) < 0)
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{
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if (!BN_usub(r,b,a)) return(0);
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r->neg=1;
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}
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else
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{
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if (!BN_usub(r,a,b)) return(0);
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r->neg=0;
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}
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return(1);
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}
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#endif
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#endif
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