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60f18e5554
git-svn-id: file:///Users/lillianskinner/Downloads/platinum/twl/TwlIPL/trunk@1 b08762b0-b915-fc4b-9d8c-17b2551a87ff
64 lines
1.4 KiB
C
64 lines
1.4 KiB
C
/* $Id$ */
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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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#include "bn_lcl.h"
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/* rp has w words, the top w words are 0 */
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void bn_from_montgomery_words(ret,a,np,w,n0)
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BN_ULONG *ret;
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BN_ULONG *a;
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BN_ULONG *np;
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int w;
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BN_ULONG n0;
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{
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BN_ULONG v0,v1,*ap,*wap;
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int i;
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v1=0;
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ap=a;
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wap= &(a[w]);
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/* Consider putting this loop in ASM */
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for (i=0; i<w; i++)
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{
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v0=bn_mul_add_words(ap,np,w,((*ap)*n0)&BN_MASK2);
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v0=(v1+v0)&BN_MASK2;
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v1=(v0 < v1)?1:0;
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if (((*wap= *wap+v0)&BN_MASK2) < v0) v1++;
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ap++; wap++;
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}
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/* ap is now wap (&a[w]) */
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i=w-1;
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if (v1 == 0)
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{
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if (ap[i] == np[i]) /* GTCHECK */
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{
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/* i=w-1 */
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for (; i>0; i--)
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if (ap[i] != np[i]) break;
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}
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v1=(ap[i] >= np[i]);
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}
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if (v1)
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(void)bn_sub_words(ret,ap,np,w);
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else
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{
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#if 0 /* Alpha does not like Memcpy */
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Memcpy(ret,ap,sizeof(BN_ULONG)*w);
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#else
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for (i=0; i<w; i++)
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ret[i]=ap[i];
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#endif
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}
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}
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