230 lines
6.8 KiB
C
230 lines
6.8 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 flash exponential and logs
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* mrflsh2.c
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*/
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#include <math.h>
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#include "miracl.h"
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#ifdef MR_FLASH
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static int expon(_MIPD_ big w,int n)
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{ /* generator for C.F. of e */
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if (n==0) return 2;
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if (n%3==2) return 2*(n/3)+2;
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else return 1;
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}
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void fexp(_MIPD_ flash x,flash y)
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{ /* calculates y=exp(x) */
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int i,n,nsq,m,sqrn,op[5];
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BOOL minus,rem;
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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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if (size(x)==0)
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{
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convert(_MIPP_ 1,y);
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return;
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}
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copy(x,y);
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MR_IN(54)
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minus=FALSE;
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if (size(y)<0)
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{
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minus=TRUE;
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negify(y,y);
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}
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ftrunc(_MIPP_ y,y,mr_mip->w9);
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n=size(y);
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if (n==MR_TOOBIG)
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{
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mr_berror(_MIPP_ MR_ERR_FLASH_OVERFLOW);
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MR_OUT
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return;
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}
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if (n==0) convert(_MIPP_ 1,y);
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else
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{
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build(_MIPP_ y,expon);
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if (minus)
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{ /* underflow to zero - bit of a bodge */
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rem=mr_mip->ERCON;
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mr_mip->ERCON=TRUE;
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fpower(_MIPP_ y,n,y);
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mr_mip->ERCON=rem;
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if (mr_mip->ERNUM)
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{
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mr_mip->ERNUM=0;
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zero(y);
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MR_OUT
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return;
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}
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}
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else fpower(_MIPP_ y,n,y);
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}
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if (size(mr_mip->w9)==0)
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{
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if (minus) frecip(_MIPP_ y,y);
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MR_OUT
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return;
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}
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sqrn=isqrt(mr_mip->lg2b*mr_mip->workprec,mr_mip->lg2b);
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nsq=0;
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copy(mr_mip->w9,mr_mip->w8);
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frecip(_MIPP_ mr_mip->w9,mr_mip->w9);
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ftrunc(_MIPP_ mr_mip->w9,mr_mip->w9,mr_mip->w9);
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m=logb2(_MIPP_ mr_mip->w9);
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if (m<sqrn)
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{ /* scale fraction down */
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nsq=sqrn-m;
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expb2(_MIPP_ nsq,mr_mip->w9);
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fdiv(_MIPP_ mr_mip->w8,mr_mip->w9,mr_mip->w8);
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}
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zero(mr_mip->w10);
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op[0]=0x4B; /* set up for x/(C+y) */
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op[1]=1;
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op[2]=0;
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for (m=sqrn;m>0;m--)
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{ /* Unwind C.F. expansion for exp(x)-1 */
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if (m%2==0) op[4]=2,op[3]=1;
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else op[4]=m,op[3]=(-1);
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flop(_MIPP_ mr_mip->w8,mr_mip->w10,op,mr_mip->w10);
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}
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op[0]=0x2C; /* set up for (x+2).y */
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op[1]=op[3]=1;
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op[2]=2;
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op[4]=0;
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for (i=0;i<nsq;i++)
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{ /* now square it back up again */
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flop(_MIPP_ mr_mip->w10,mr_mip->w10,op,mr_mip->w10);
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}
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op[2]=1;
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flop(_MIPP_ mr_mip->w10,y,op,y);
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if (minus) frecip(_MIPP_ y,y);
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MR_OUT
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}
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void flog(_MIPD_ flash x,flash y)
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{ /* calculate y=log(x) to base e */
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BOOL hack;
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int op[5];
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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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copy(x,y);
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if (mr_mip->ERNUM) return;
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if (size(y)==1)
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{
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zero(y);
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return;
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}
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MR_IN(55)
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if (size(y)<=0)
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{
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mr_berror(_MIPP_ MR_ERR_NEG_LOG);
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MR_OUT
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return;
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}
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hack=FALSE;
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if (mr_lent(y)<=2)
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{ /* for 'simple' values of y */
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hack=TRUE;
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build(_MIPP_ mr_mip->w11,expon);
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fdiv(_MIPP_ y,mr_mip->w11,y);
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}
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op[0]=0x68;
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op[1]=op[3]=1;
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op[2]=(-1);
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op[4]=0;
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mr_mip->workprec=mr_mip->stprec;
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dconv(_MIPP_ log(fdsize(_MIPP_ y)),mr_mip->w11);
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while (mr_mip->workprec!=mr_mip->nib)
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{ /* Newtons iteration w11=w11+(y-exp(w11))/exp(w11) */
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if (mr_mip->workprec<mr_mip->nib) mr_mip->workprec*=2;
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if (mr_mip->workprec>=mr_mip->nib) mr_mip->workprec=mr_mip->nib;
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else if (mr_mip->workprec*2>mr_mip->nib) mr_mip->workprec=(mr_mip->nib+1)/2;
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fexp(_MIPP_ mr_mip->w11,mr_mip->w12);
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flop(_MIPP_ y,mr_mip->w12,op,mr_mip->w12);
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fadd(_MIPP_ mr_mip->w12,mr_mip->w11,mr_mip->w11);
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}
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copy(mr_mip->w11,y);
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if (hack) fincr(_MIPP_ y,1,1,y);
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MR_OUT
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}
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void fpowf(_MIPD_ flash x,flash y,flash z)
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{ /* raise flash number to flash power *
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* z=x^y -> z=exp(y.log(x)) */
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int n;
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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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MR_IN(56)
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n=size(y);
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if (mr_abs(n)<MR_TOOBIG)
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{ /* y is small int */
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fpower(_MIPP_ x,n,z);
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MR_OUT
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return;
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}
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frecip(_MIPP_ y,mr_mip->w13);
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n=size(mr_mip->w13);
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if (mr_abs(n)<MR_TOOBIG)
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{ /* 1/y is small int */
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froot(_MIPP_ x,n,z);
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MR_OUT
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return;
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}
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copy(x,z);
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flog(_MIPP_ z,z);
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fdiv(_MIPP_ z,mr_mip->w13,z);
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fexp(_MIPP_ z,z);
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MR_OUT
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}
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#endif
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