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 9Copyright 2009 Free Software Foundation, Inc. 10 11This file is part of the GNU MP Library. 12 13The GNU MP Library is free software; you can redistribute it and/or modify 14it 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 20or 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 26or both in parallel, as here. 27 28The GNU MP Library is distributed in the hope that it will be useful, but 29WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 30or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 31for more details. 32 33You should have received copies of the GNU General Public License and the 34GNU Lesser General Public License along with the GNU MP Library. If not, 35see https://www.gnu.org/licenses/. */ 36 37 38#include "gmp-impl.h" 39 40#if HAVE_NATIVE_mpn_addlsh_n 41#define DO_mpn_addlsh_n(dst,src,n,s,ws) mpn_addlsh_n(dst,dst,src,n,s) 42#else 43static mp_limb_t 44DO_mpn_addlsh_n(mp_ptr dst, mp_srcptr src, mp_size_t n, unsigned int s, mp_ptr ws) 45{ 46#if USE_MUL_1 && 0 47 return mpn_addmul_1(dst,src,n,CNST_LIMB(1) <<(s)); 48#else 49 mp_limb_t __cy; 50 __cy = mpn_lshift(ws,src,n,s); 51 return __cy + mpn_add_n(dst,dst,ws,n); 52#endif 53} 54#endif 55 56/* Evaluates a polynomial of degree k >= 3. */ 57int 58mpn_toom_eval_pm2rexp (mp_ptr rp, mp_ptr rm, 59 unsigned int q, mp_srcptr ap, mp_size_t n, mp_size_t t, 60 unsigned int s, mp_ptr ws) 61{ 62 unsigned int i; 63 int neg; 64 /* {ap,q*n+t} -> {rp,n+1} {rm,n+1} , with {ws, n+1}*/ 65 ASSERT (n >= t); 66 ASSERT (s != 0); /* or _eval_pm1 should be used */ 67 ASSERT (q > 1); 68 ASSERT (s*q < GMP_NUMB_BITS); 69 rp[n] = mpn_lshift(rp, ap, n, s*q); 70 ws[n] = mpn_lshift(ws, ap+n, n, s*(q-1)); 71 if( (q & 1) != 0) { 72 ASSERT_NOCARRY(mpn_add(ws,ws,n+1,ap+n*q,t)); 73 rp[n] += DO_mpn_addlsh_n(rp, ap+n*(q-1), n, s, rm); 74 } else { 75 ASSERT_NOCARRY(mpn_add(rp,rp,n+1,ap+n*q,t)); 76 } 77 for(i=2; i<q-1; i++) 78 { 79 rp[n] += DO_mpn_addlsh_n(rp, ap+n*i, n, s*(q-i), rm); 80 i++; 81 ws[n] += DO_mpn_addlsh_n(ws, ap+n*i, n, s*(q-i), rm); 82 }; 83 84 neg = (mpn_cmp (rp, ws, n + 1) < 0) ? ~0 : 0; 85 86#if HAVE_NATIVE_mpn_add_n_sub_n 87 if (neg) 88 mpn_add_n_sub_n (rp, rm, ws, rp, n + 1); 89 else 90 mpn_add_n_sub_n (rp, rm, rp, ws, n + 1); 91#else /* !HAVE_NATIVE_mpn_add_n_sub_n */ 92 if (neg) 93 mpn_sub_n (rm, ws, rp, n + 1); 94 else 95 mpn_sub_n (rm, rp, ws, n + 1); 96 97 ASSERT_NOCARRY (mpn_add_n (rp, rp, ws, n + 1)); 98#endif /* !HAVE_NATIVE_mpn_add_n_sub_n */ 99 100 return neg; 101} 102