1/* mpn_bdiv_dbm1c -- divide an mpn number by a divisor of B-1, where B is the 2 limb base. The dbm1c moniker means "Divisor of B Minus 1 with Carry". 3 4 THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY 5 SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST 6 GUARANTEED THAT IT'LL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE. 7 8Copyright 2008, 2009 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#include "longlong.h" 38 39 40mp_limb_t 41mpn_bdiv_dbm1c (mp_ptr qp, mp_srcptr ap, mp_size_t n, mp_limb_t bd, mp_limb_t h) 42{ 43 mp_limb_t a, p0, p1, cy; 44 mp_size_t i; 45 46 for (i = 0; i < n; i++) 47 { 48 a = ap[i]; 49 umul_ppmm (p1, p0, a, bd << GMP_NAIL_BITS); 50 p0 >>= GMP_NAIL_BITS; 51 cy = h < p0; 52 h = (h - p0) & GMP_NUMB_MASK; 53 qp[i] = h; 54 h = h - p1 - cy; 55 } 56 57 return h; 58} 59