1 /* mpn_redc_2. Set rp[] <- up[]/R^n mod mp[]. Clobber up[].
2 mp[] is n limbs; up[] is 2n limbs.
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 Copyright (C) 2000-2002, 2004, 2008, 2012 Free Software Foundation, Inc.
8
9 This file is part of the GNU MP Library.
10
11 The GNU MP Library is free software; you can redistribute it and/or modify
12 it under the terms of either:
13
14 * the GNU Lesser General Public License as published by the Free
15 Software Foundation; either version 3 of the License, or (at your
16 option) any later version.
17
18 or
19
20 * the GNU General Public License as published by the Free Software
21 Foundation; either version 2 of the License, or (at your option) any
22 later version.
23
24 or both in parallel, as here.
25
26 The GNU MP Library is distributed in the hope that it will be useful, but
27 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
28 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
29 for more details.
30
31 You should have received copies of the GNU General Public License and the
32 GNU Lesser General Public License along with the GNU MP Library. If not,
33 see https://www.gnu.org/licenses/. */
34
35 #include "gmp-impl.h"
36 #include "longlong.h"
37
38
39 #if GMP_NAIL_BITS != 0
40 you lose
41 #endif
42
43 /* For testing purposes, define our own mpn_addmul_2 if there is none already
44 available. */
45 #ifndef HAVE_NATIVE_mpn_addmul_2
46 #undef mpn_addmul_2
47 static mp_limb_t
mpn_addmul_2(mp_ptr rp,mp_srcptr up,mp_size_t n,mp_srcptr vp)48 mpn_addmul_2 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_srcptr vp)
49 {
50 rp[n] = mpn_addmul_1 (rp, up, n, vp[0]);
51 return mpn_addmul_1 (rp + 1, up, n, vp[1]);
52 }
53 #endif
54
55 #if defined (__GNUC__) && ! defined (NO_ASM) \
56 && defined (__ia64) && W_TYPE_SIZE == 64
57 #define umul2low(ph, pl, uh, ul, vh, vl) \
58 do { \
59 mp_limb_t _ph, _pl; \
60 __asm__ ("xma.hu %0 = %3, %5, f0\n\t" \
61 "xma.l %1 = %3, %5, f0\n\t" \
62 ";;\n\t" \
63 "xma.l %0 = %3, %4, %0\n\t" \
64 ";;\n\t" \
65 "xma.l %0 = %2, %5, %0" \
66 : "=&f" (ph), "=&f" (pl) \
67 : "f" (uh), "f" (ul), "f" (vh), "f" (vl)); \
68 } while (0)
69 #endif
70
71 #ifndef umul2low
72 #define umul2low(ph, pl, uh, ul, vh, vl) \
73 do { \
74 mp_limb_t _ph, _pl; \
75 umul_ppmm (_ph, _pl, ul, vl); \
76 (ph) = _ph + (ul) * (vh) + (uh) * (vl); \
77 (pl) = _pl; \
78 } while (0)
79 #endif
80
81 mp_limb_t
mpn_redc_2(mp_ptr rp,mp_ptr up,mp_srcptr mp,mp_size_t n,mp_srcptr mip)82 mpn_redc_2 (mp_ptr rp, mp_ptr up, mp_srcptr mp, mp_size_t n, mp_srcptr mip)
83 {
84 mp_limb_t q[2];
85 mp_size_t j;
86 mp_limb_t upn;
87 mp_limb_t cy;
88
89 ASSERT (n > 0);
90 ASSERT_MPN (up, 2*n);
91
92 if ((n & 1) != 0)
93 {
94 up[0] = mpn_addmul_1 (up, mp, n, (up[0] * mip[0]) & GMP_NUMB_MASK);
95 up++;
96 }
97
98 for (j = n - 2; j >= 0; j -= 2)
99 {
100 umul2low (q[1], q[0], mip[1], mip[0], up[1], up[0]);
101 upn = up[n]; /* mpn_addmul_2 overwrites this */
102 up[1] = mpn_addmul_2 (up, mp, n, q);
103 up[0] = up[n];
104 up[n] = upn;
105 up += 2;
106 }
107
108 cy = mpn_add_n (rp, up, up - n, n);
109 return cy;
110 }
111