1/* mpn_mullo_basecase -- Internal routine to multiply two natural 2 numbers of length n and return the low part. 3 4 THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE. IT IS ONLY 5 SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES. 6 7 8Copyright (C) 2000, 2002, 2004, 2015 Free Software Foundation, Inc. 9 10This file is part of the GNU MP Library. 11 12The GNU MP Library is free software; you can redistribute it and/or modify 13it under the terms of either: 14 15 * the GNU Lesser General Public License as published by the Free 16 Software Foundation; either version 3 of the License, or (at your 17 option) any later version. 18 19or 20 21 * the GNU General Public License as published by the Free Software 22 Foundation; either version 2 of the License, or (at your option) any 23 later version. 24 25or both in parallel, as here. 26 27The GNU MP Library is distributed in the hope that it will be useful, but 28WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 29or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 30for more details. 31 32You should have received copies of the GNU General Public License and the 33GNU Lesser General Public License along with the GNU MP Library. If not, 34see https://www.gnu.org/licenses/. */ 35 36#include "gmp-impl.h" 37 38/* FIXME: Should optionally use mpn_mul_2/mpn_addmul_2. */ 39 40#ifndef MULLO_VARIANT 41#define MULLO_VARIANT 2 42#endif 43 44 45#if MULLO_VARIANT == 1 46void 47mpn_mullo_basecase (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n) 48{ 49 mp_size_t i; 50 51 mpn_mul_1 (rp, up, n, vp[0]); 52 53 for (i = n - 1; i > 0; i--) 54 { 55 vp++; 56 rp++; 57 mpn_addmul_1 (rp, up, i, vp[0]); 58 } 59} 60#endif 61 62 63#if MULLO_VARIANT == 2 64void 65mpn_mullo_basecase (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n) 66{ 67 mp_limb_t h; 68 69 h = up[0] * vp[n - 1]; 70 71 if (n != 1) 72 { 73 mp_size_t i; 74 mp_limb_t v0; 75 76 v0 = *vp++; 77 h += up[n - 1] * v0 + mpn_mul_1 (rp, up, n - 1, v0); 78 rp++; 79 80 for (i = n - 2; i > 0; i--) 81 { 82 v0 = *vp++; 83 h += up[i] * v0 + mpn_addmul_1 (rp, up, i, v0); 84 rp++; 85 } 86 } 87 88 rp[0] = h; 89} 90#endif 91