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-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 43 static mp_limb_t 44 DO_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. */ 57 int 58 mpn_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