github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/generic/toom_eval_pm2rexp.c (about)

     1  /* mpn_toom_eval_pm2rexp -- Evaluate a polynomial in +2^-k and -2^-k
     2  
     3     Contributed to the GNU project by Marco Bodrato
     4  
     5     THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE.  IT IS ONLY
     6     SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES.  IN FACT, IT IS ALMOST
     7     GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
     8  
     9  Copyright 2009 Free Software Foundation, Inc.
    10  
    11  This file is part of the GNU MP Library.
    12  
    13  The GNU MP Library is free software; you can redistribute it and/or modify
    14  it under the terms of either:
    15  
    16    * the GNU Lesser General Public License as published by the Free
    17      Software Foundation; either version 3 of the License, or (at your
    18      option) any later version.
    19  
    20  or
    21  
    22    * the GNU General Public License as published by the Free Software
    23      Foundation; either version 2 of the License, or (at your option) any
    24      later version.
    25  
    26  or both in parallel, as here.
    27  
    28  The GNU MP Library is distributed in the hope that it will be useful, but
    29  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    30  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    31  for more details.
    32  
    33  You should have received copies of the GNU General Public License and the
    34  GNU Lesser General Public License along with the GNU MP Library.  If not,
    35  see https://www.gnu.org/licenses/.  */
    36  
    37  
    38  #include "gmp.h"
    39  #include "gmp-impl.h"
    40  
    41  #if HAVE_NATIVE_mpn_addlsh_n
    42  #define DO_mpn_addlsh_n(dst,src,n,s,ws) mpn_addlsh_n(dst,dst,src,n,s)
    43  #else
    44  static mp_limb_t
    45  DO_mpn_addlsh_n(mp_ptr dst, mp_srcptr src, mp_size_t n, unsigned int s, mp_ptr ws)
    46  {
    47  #if USE_MUL_1 && 0
    48    return mpn_addmul_1(dst,src,n,CNST_LIMB(1) <<(s));
    49  #else
    50    mp_limb_t __cy;
    51    __cy = mpn_lshift(ws,src,n,s);
    52    return    __cy + mpn_add_n(dst,dst,ws,n);
    53  #endif
    54  }
    55  #endif
    56  
    57  /* Evaluates a polynomial of degree k >= 3. */
    58  int
    59  mpn_toom_eval_pm2rexp (mp_ptr rp, mp_ptr rm,
    60  		      unsigned int q, mp_srcptr ap, mp_size_t n, mp_size_t t,
    61  		      unsigned int s, mp_ptr ws)
    62  {
    63    unsigned int i;
    64    int neg;
    65    /* {ap,q*n+t} -> {rp,n+1} {rm,n+1} , with {ws, n+1}*/
    66    ASSERT (n >= t);
    67    ASSERT (s != 0); /* or _eval_pm1 should be used */
    68    ASSERT (q > 1);
    69    ASSERT (s*q < GMP_NUMB_BITS);
    70    rp[n] = mpn_lshift(rp, ap, n, s*q);
    71    ws[n] = mpn_lshift(ws, ap+n, n, s*(q-1));
    72    if( (q & 1) != 0) {
    73      ASSERT_NOCARRY(mpn_add(ws,ws,n+1,ap+n*q,t));
    74      rp[n] += DO_mpn_addlsh_n(rp, ap+n*(q-1), n, s, rm);
    75    } else {
    76      ASSERT_NOCARRY(mpn_add(rp,rp,n+1,ap+n*q,t));
    77    }
    78    for(i=2; i<q-1; i++)
    79    {
    80      rp[n] += DO_mpn_addlsh_n(rp, ap+n*i, n, s*(q-i), rm);
    81      i++;
    82      ws[n] += DO_mpn_addlsh_n(ws, ap+n*i, n, s*(q-i), rm);
    83    };
    84  
    85    neg = (mpn_cmp (rp, ws, n + 1) < 0) ? ~0 : 0;
    86  
    87  #if HAVE_NATIVE_mpn_add_n_sub_n
    88    if (neg)
    89      mpn_add_n_sub_n (rp, rm, ws, rp, n + 1);
    90    else
    91      mpn_add_n_sub_n (rp, rm, rp, ws, n + 1);
    92  #else /* !HAVE_NATIVE_mpn_add_n_sub_n */
    93    if (neg)
    94      mpn_sub_n (rm, ws, rp, n + 1);
    95    else
    96      mpn_sub_n (rm, rp, ws, n + 1);
    97  
    98    ASSERT_NOCARRY (mpn_add_n (rp, rp, ws, n + 1));
    99  #endif /* !HAVE_NATIVE_mpn_add_n_sub_n */
   100  
   101    return neg;
   102  }