92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
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/* mpn_toom_eval_pm2rexp -- Evaluate a polynomial in +2^-k and -2^-k
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Contributed to the GNU project by Marco Bodrato
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THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
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SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
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GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
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Copyright 2009 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
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#include "mpir.h"
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#include "gmp-impl.h"
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#if HAVE_NATIVE_mpn_addlsh_n
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#define DO_mpn_addlsh_n(dst,src,n,s,ws) mpn_addlsh_n(dst,dst,src,n,s)
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#else
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static mp_limb_t
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DO_mpn_addlsh_n(mp_ptr dst, mp_srcptr src, mp_size_t n, unsigned int s, mp_ptr ws)
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{
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#if USE_MUL_1 && 0
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return mpn_addmul_1(dst,src,n,CNST_LIMB(1) <<(s));
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#else
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mp_limb_t __cy;
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__cy = mpn_lshift(ws,src,n,s);
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return __cy + mpn_add_n(dst,dst,ws,n);
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#endif
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}
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#endif
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/* Evaluates a polynomial of degree k >= 3. */
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int
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mpn_toom_eval_pm2rexp (mp_ptr rp, mp_ptr rm,
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unsigned int q, mp_srcptr ap, mp_size_t n, mp_size_t t,
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unsigned int s, mp_ptr ws)
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{
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unsigned int i;
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int neg;
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/* {ap,q*n+t} -> {rp,n+1} {rm,n+1} , with {ws, n+1}*/
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ASSERT (n >= t);
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ASSERT (s != 0); /* or _eval_pm1 should be used */
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ASSERT (q > 1);
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ASSERT (s*q < GMP_NUMB_BITS);
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rp[n] = mpn_lshift(rp, ap, n, s*q);
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ws[n] = mpn_lshift(ws, ap+n, n, s*(q-1));
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if( (q & 1) != 0) {
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ASSERT_NOCARRY(mpn_add(ws,ws,n+1,ap+n*q,t));
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rp[n] += DO_mpn_addlsh_n(rp, ap+n*(q-1), n, s, rm);
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} else {
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ASSERT_NOCARRY(mpn_add(rp,rp,n+1,ap+n*q,t));
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}
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for(i=2; i<q-1; i++)
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{
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rp[n] += DO_mpn_addlsh_n(rp, ap+n*i, n, s*(q-i), rm);
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i++;
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ws[n] += DO_mpn_addlsh_n(ws, ap+n*i, n, s*(q-i), rm);
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};
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neg = (mpn_cmp (rp, ws, n + 1) < 0) ? ~0 : 0;
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#if HAVE_NATIVE_mpn_add_n_sub_n
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if (neg)
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mpn_add_n_sub_n (rp, rm, ws, rp, n + 1);
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else
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mpn_add_n_sub_n (rp, rm, rp, ws, n + 1);
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#else /* !HAVE_NATIVE_mpn_add_n_sub_n */
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if (neg)
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mpn_sub_n (rm, ws, rp, n + 1);
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else
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mpn_sub_n (rm, rp, ws, n + 1);
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ASSERT_NOCARRY (mpn_add_n (rp, rp, ws, n + 1));
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#endif /* !HAVE_NATIVE_mpn_add_n_sub_n */
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return neg;
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}
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