100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/*
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dnl Copyright 2009 Jason Moxham
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dnl This file is part of the MPIR Library.
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dnl The MPIR Library is free software; you can redistribute it and/or modify
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dnl it under the terms of the GNU Lesser General Public License as published
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dnl by the Free Software Foundation; either version 2.1 of the License, or (at
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dnl your option) any later version.
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dnl The MPIR Library is distributed in the hope that it will be useful, but
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dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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dnl License for more details.
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dnl You should have received a copy of the GNU Lesser General Public License
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dnl along with the MPIR Library; see the file COPYING.LIB. If not, write
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dnl to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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dnl Boston, MA 02110-1301, USA.
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*/
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#include "mpir.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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// d is mormalized
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#define udiv_inverse(i,d) do{mp_limb_t __X;udiv_qrnnd(i,__X,~(d),GMP_LIMB_MAX,d);}while(0)
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// note double lenght inverse can easily be calculated from single length inverse
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// d is normalize
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#define udiv_double_inverse(ih,il,d) \
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do{mp_limb_t __X;udiv_qrnnd(ih,__X,~(d),GMP_LIMB_MAX,d);udiv_qrnnd(il,__X,__X,GMP_LIMB_MAX,d);}while(0)
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// set to 1=store or 0=not store
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#define STORE_QUOTIENT 1
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// set to 0=udiv 1=gmp-preinv 2-barrett
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#define UDIV_METHOD 1
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#if UDIV_NEEDS_NORMALIZATION==1 || UDIV_METHOD==1
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#define NORMALIZE 1
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#else
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#define NORMALIZE 0
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#endif
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#if UDIV_METHOD==0
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#define UDIV(q,r,h,l,d,i) udiv_qrnnd(q,r,h,l,d)
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#endif
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#if UDIV_METHOD==1
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#define UDIV udiv_qrnnd_preinv
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#endif
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#if UDIV_METHOD==2
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#define UDIV udiv_qrnnd_barrett
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#endif
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#if STORE_QUOTIENT
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mp_limb_t mpn_divrem_euclidean_qr_1(mp_ptr qp,mp_size_t qxn, mp_srcptr xp,mp_size_t n,mp_limb_t d)
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#else
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mp_limb_t mpn_divrem_euclidean_r_1(mp_srcptr xp,mp_size_t n,mp_limb_t d)
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#endif
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{mp_size_t j;
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mp_limb_t r=0,s=0,h,l,q,i;
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#if STORE_QUOTIENT
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ASSERT_ALWAYS(qxn==0);
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#endif
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ASSERT(n>0);ASSERT(d!=0);ASSERT_MPN(xp,n);
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#if STORE_QUOTIENT
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ASSERT(MPN_SAME_OR_SEPARATE_P(qp,xp,n));
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#endif
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// for n=1 or n=2 probably faster to do a special case
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#if NORMALIZE==1
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count_leading_zeros(s,d);d=d<<s;
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invert_limb(i,d);
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#endif
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for(j=n-1;j>=0;j--)
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{l=xp[j]; // out dlimb is (h=r,l)
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h=(l>>((GMP_LIMB_BITS-1-s))>>1);l=l<<s;// shift dlimb left by s
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h=h+r; // carry in
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UDIV(q,r,h,l,d,i); // carry out , carry-out to carry-in is the critical latency bottleneck
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#if STORE_QUOTIENT
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qp[j]=q;
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#endif
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}
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ASSERT((r<<(GMP_LIMB_BITS-1-s)<<1)==0);// ie bottom s bits of r are zero
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r>>=s;
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return r;} // so (xp,n) = (qp,n)*d +r and 0 <= r < d
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/*
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in hensel-div we use shiftout which means we can use mmx shifting and dont need to always use it
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in euclid-div shiftout needs a final div for the remainder
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*/
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