/* $Id$ */
/*
 * Copyright (C) 1998-2002 RSA Security Inc. All rights reserved.
 *
 * This work contains proprietary information of RSA Security.
 * Distribution is limited to authorized licensees of RSA
 * Security. Any unauthorized reproduction, distribution or
 * modification of this work is strictly prohibited.
 *
 */
#include "bn_lcl.h"

/* rp has w words, the top w words are 0 */
void bn_from_montgomery_words(ret,a,np,w,n0)
BN_ULONG *ret;
BN_ULONG *a;
BN_ULONG *np;
int w;
BN_ULONG n0;
    {
    BN_ULONG v0,v1,*ap,*wap;
    int i;

    v1=0;

    ap=a;
    wap= &(a[w]);
    /* Consider putting this loop in ASM */
    for (i=0; i<w; i++)
        {
        v0=bn_mul_add_words(ap,np,w,((*ap)*n0)&BN_MASK2);
        v0=(v1+v0)&BN_MASK2;
        v1=(v0 < v1)?1:0;
        if (((*wap= *wap+v0)&BN_MASK2) < v0) v1++;
        ap++; wap++;
        }

    /* ap is now wap (&a[w]) */
    i=w-1;
    if (v1 == 0)
        {
        if (ap[i] == np[i]) /* GTCHECK */
            {
            /* i=w-1 */
            for (; i>0; i--)
                if (ap[i] != np[i]) break;
            }
        v1=(ap[i] >= np[i]);
        }
    if (v1)
        (void)bn_sub_words(ret,ap,np,w);
    else
        {
#if 0 /* Alpha does not like Memcpy */
        Memcpy(ret,ap,sizeof(BN_ULONG)*w);
#else
        for (i=0; i<w; i++)
            ret[i]=ap[i];
#endif
        }
    }