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60f18e5554
git-svn-id: file:///Users/lillianskinner/Downloads/platinum/twl/TwlIPL/trunk@1 b08762b0-b915-fc4b-9d8c-17b2551a87ff
101 lines
1.8 KiB
C
101 lines
1.8 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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#ifndef OPT_BN_ASM
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#ifndef BN_DIV_WORDS
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#define BN_DIV_WORDS
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#endif
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#endif
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#ifdef BN_DIV_WORDS
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#if defined(BN_LLONG)
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BN_ULONG bn_div_words(h,l,d)
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BN_ULONG h,l,d;
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{
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return((BN_ULONG)(((((BN_ULLONG)h)<<BN_BITS2)|l)/(BN_ULLONG)d));
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}
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#else
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/* Divide h-l by d and return the result. */
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/* I need to test this some more */
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BN_ULONG bn_div_words(h,l,d)
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BN_ULONG h,l,d;
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{
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BN_ULONG dh,dl,q,ret=0,th,tl,t;
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int i,count=2;
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if (d == 0) return(BN_MASK2);
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i=BN_num_bits_word(d);
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if ((i != BN_BITS2) && (h > ((BN_ULONG)1)<<i))
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{
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return(0);
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}
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i=BN_BITS2-i;
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if (h >= d) h-=d;
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if (i)
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{
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d=(d<<i)&BN_MASK2;
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h=((h<<i)|(l>>(BN_BITS2-i)))&BN_MASK2;
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l=(l<<i)&BN_MASK2;
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}
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dh=(d>>BN_BITS4)&BN_MASK2lh;
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dl=(d&BN_MASK2l);
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for (;;)
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{
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if ((h>>BN_BITS4) == dh)
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q=BN_MASK2l;
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else
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q=h/dh;
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for (;;)
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{
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t=(h-q*dh)&BN_MASK2;
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if ((t&BN_MASK2h) ||
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(((dl*q)&BN_MASK2) <= ((
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(t<<BN_BITS4)+
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((l>>BN_BITS4)&BN_MASK2lh))&BN_MASK2)))
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break;
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q--;
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}
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th=(q*dh)&BN_MASK2;
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tl=(q*dl)&BN_MASK2;
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t=(tl>>BN_BITS4);
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tl=(tl&BN_MASK2lh)<<BN_BITS4;
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th=(th+t)&BN_MASK2;
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if (l < tl) th++;
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l=(l-tl)&BN_MASK2;
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if (h < th)
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{
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h=(h+d)&BN_MASK2;
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q--;
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}
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h=(h-th)&BN_MASK2;
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if (--count == 0) break;
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ret=(q&BN_MASK2lh)<<BN_BITS4;
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h=((h<<BN_BITS4)|(l>>BN_BITS4))&BN_MASK2;
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l=(l&BN_MASK2l)<<BN_BITS4;
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}
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ret|=q;
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return(ret);
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}
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#endif
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#endif /* BN_DIV_WORDS */
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