1 /* mpn_sbpi1_div_qr -- Schoolbook division using the Möller-Granlund 3/2
4 Contributed to the GNU project by Torbjorn Granlund.
6 THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
7 SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
8 GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
10 Copyright 2007, 2009 Free Software Foundation, Inc.
12 This file is part of the GNU MP Library.
14 The GNU MP Library is free software; you can redistribute it and/or modify
15 it under the terms of the GNU Lesser General Public License as published by
16 the Free Software Foundation; either version 3 of the License, or (at your
17 option) any later version.
19 The GNU MP Library is distributed in the hope that it will be useful, but
20 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
21 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
22 License for more details.
24 You should have received a copy of the GNU Lesser General Public License
25 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
33 mpn_sbpi1_div_qr (mp_ptr qp,
34 mp_ptr np, mp_size_t nn,
35 mp_srcptr dp, mp_size_t dn,
47 ASSERT ((dp[dn-1] & GMP_NUMB_HIGHBIT) != 0);
51 qh = mpn_cmp (np - dn, dp, dn) >= 0;
53 mpn_sub_n (np - dn, np - dn, dp, dn);
57 dn -= 2; /* offset dn by 2 for main division loops,
58 saving two iterations in mpn_submul_1. */
66 for (i = nn - (dn + 2); i > 0; i--)
69 if (UNLIKELY (n1 == d1) && np[1] == d0)
72 mpn_submul_1 (np - dn, dp, dn + 2, q);
73 n1 = np[1]; /* update n1, last loop's value will now be invalid */
77 udiv_qr_3by2 (q, n1, n0, n1, np[1], np[0], d1, d0, dinv);
79 cy = mpn_submul_1 (np - dn, dp, dn, q);
82 n0 = (n0 - cy) & GMP_NUMB_MASK;
84 n1 = (n1 - cy1) & GMP_NUMB_MASK;
87 if (UNLIKELY (cy != 0))
89 n1 += d1 + mpn_add_n (np - dn, np - dn, dp, dn + 1);