246 lines
6.3 KiB
C
246 lines
6.3 KiB
C
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/***************************************************************************
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*
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Copyright 2013 CertiVox UK Ltd. *
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*
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This file is part of CertiVox MIRACL Crypto SDK. *
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*
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The CertiVox MIRACL Crypto SDK provides developers with an *
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extensive and efficient set of cryptographic functions. *
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For further information about its features and functionalities please *
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refer to http://www.certivox.com *
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*
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* The CertiVox MIRACL Crypto SDK is free software: you can *
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redistribute it and/or modify it under the terms of the *
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GNU Affero General Public License as published by the *
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Free Software Foundation, either version 3 of the License, *
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or (at your option) any later version. *
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*
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* The CertiVox MIRACL Crypto SDK is distributed in the hope *
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that it will be useful, but WITHOUT ANY WARRANTY; without even the *
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implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. *
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See the GNU Affero General Public License for more details. *
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*
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* You should have received a copy of the GNU Affero General Public *
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License along with CertiVox MIRACL Crypto SDK. *
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If not, see <http://www.gnu.org/licenses/>. *
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*
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You can be released from the requirements of the license by purchasing *
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a commercial license. Buying such a license is mandatory as soon as you *
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develop commercial activities involving the CertiVox MIRACL Crypto SDK *
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without disclosing the source code of your own applications, or shipping *
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the CertiVox MIRACL Crypto SDK with a closed source product. *
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*
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***************************************************************************/
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/*
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* MIRACL bit manipulation routines
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* mrbits.c
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*/
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#include <stdlib.h>
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#include "miracl.h"
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#ifdef MR_FP
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#include <math.h>
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#endif
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int logb2(_MIPD_ big x)
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{ /* returns number of bits in x */
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int xl,lg2;
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mr_small top;
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#ifdef MR_OS_THREADS
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miracl *mr_mip=get_mip();
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#endif
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if (mr_mip->ERNUM || size(x)==0) return 0;
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MR_IN(49)
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#ifndef MR_ALWAYS_BINARY
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if (mr_mip->base==mr_mip->base2)
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{
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#endif
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xl=(int)(x->len&MR_OBITS);
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lg2=mr_mip->lg2b*(xl-1);
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top=x->w[xl-1];
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while (top>=1)
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{
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lg2++;
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top/=2;
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}
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#ifndef MR_ALWAYS_BINARY
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}
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else
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{
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copy(x,mr_mip->w0);
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insign(PLUS,mr_mip->w0);
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lg2=0;
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while (mr_mip->w0->len>1)
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{
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#ifdef MR_FP_ROUNDING
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mr_sdiv(_MIPP_ mr_mip->w0,mr_mip->base2,mr_invert(mr_mip->base2),mr_mip->w0);
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#else
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mr_sdiv(_MIPP_ mr_mip->w0,mr_mip->base2,mr_mip->w0);
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#endif
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lg2+=mr_mip->lg2b;
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}
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while (mr_mip->w0->w[0]>=1)
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{
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lg2++;
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mr_mip->w0->w[0]/=2;
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}
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}
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#endif
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MR_OUT
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return lg2;
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}
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void sftbit(_MIPD_ big x,int n,big z)
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{ /* shift x by n bits */
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int m;
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mr_small sm;
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#ifdef MR_OS_THREADS
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miracl *mr_mip=get_mip();
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#endif
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if (mr_mip->ERNUM) return;
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copy(x,z);
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if (n==0) return;
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MR_IN(47)
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m=mr_abs(n);
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sm=mr_shiftbits((mr_small)1,m%mr_mip->lg2b);
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if (n>0)
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{ /* shift left */
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#ifndef MR_ALWAYS_BINARY
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if (mr_mip->base==mr_mip->base2)
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{
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#endif
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mr_shift(_MIPP_ z,n/mr_mip->lg2b,z);
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mr_pmul(_MIPP_ z,sm,z);
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#ifndef MR_ALWAYS_BINARY
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}
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else
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{
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expb2(_MIPP_ m,mr_mip->w1);
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multiply(_MIPP_ z,mr_mip->w1,z);
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}
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#endif
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}
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else
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{ /* shift right */
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#ifndef MR_ALWAYS_BINARY
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if (mr_mip->base==mr_mip->base2)
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{
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#endif
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mr_shift(_MIPP_ z,n/mr_mip->lg2b,z);
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#ifdef MR_FP_ROUNDING
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mr_sdiv(_MIPP_ z,sm,mr_invert(sm),z);
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#else
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mr_sdiv(_MIPP_ z,sm,z);
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#endif
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#ifndef MR_ALWAYS_BINARY
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}
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else
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{
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expb2(_MIPP_ m,mr_mip->w1);
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divide(_MIPP_ z,mr_mip->w1,z);
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}
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#endif
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}
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MR_OUT
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}
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void expb2(_MIPD_ int n,big x)
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{ /* sets x=2^n */
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int r,p;
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#ifndef MR_ALWAYS_BINARY
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int i;
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#endif
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#ifdef MR_OS_THREADS
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miracl *mr_mip=get_mip();
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#endif
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if (mr_mip->ERNUM) return;
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convert(_MIPP_ 1,x);
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if (n==0) return;
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MR_IN(149)
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if (n<0)
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{
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mr_berror(_MIPP_ MR_ERR_NEG_POWER);
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MR_OUT
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return;
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}
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r=n/mr_mip->lg2b;
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p=n%mr_mip->lg2b;
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#ifndef MR_ALWAYS_BINARY
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if (mr_mip->base==mr_mip->base2)
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{
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#endif
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mr_shift(_MIPP_ x,r,x);
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x->w[x->len-1]=mr_shiftbits(x->w[x->len-1],p);
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#ifndef MR_ALWAYS_BINARY
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}
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else
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{
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for (i=1;i<=r;i++)
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mr_pmul(_MIPP_ x,mr_mip->base2,x);
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mr_pmul(_MIPP_ x,mr_shiftbits((mr_small)1,p),x);
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}
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#endif
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MR_OUT
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}
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#ifndef MR_NO_RAND
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void bigbits(_MIPD_ int n,big x)
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{ /* sets x as random < 2^n */
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mr_small r;
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mr_lentype wlen;
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#ifdef MR_FP
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mr_small dres;
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#endif
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#ifdef MR_OS_THREADS
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miracl *mr_mip=get_mip();
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#endif
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zero(x);
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if (mr_mip->ERNUM || n<=0) return;
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MR_IN(150)
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expb2(_MIPP_ n,mr_mip->w1);
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wlen=mr_mip->w1->len;
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do
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{
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r=brand(_MIPPO_ );
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if (mr_mip->base==0) x->w[x->len++]=r;
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else x->w[x->len++]=MR_REMAIN(r,mr_mip->base);
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} while (x->len<wlen);
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#ifndef MR_ALWAYS_BINARY
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if (mr_mip->base==mr_mip->base2)
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{
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#endif
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x->w[wlen-1]=MR_REMAIN(x->w[wlen-1],mr_mip->w1->w[wlen-1]);
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mr_lzero(x);
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#ifndef MR_ALWAYS_BINARY
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}
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else
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{
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divide(_MIPP_ x,mr_mip->w1,mr_mip->w1);
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}
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#endif
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MR_OUT
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}
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#endif
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