1 /* mpn_redc_2. Set cp[] <- 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, 2001, 2002, 2004, 2008 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 the GNU Lesser General Public License as published by 13 the Free Software Foundation; either version 3 of the License, or (at your 14 option) any later version. 15 16 The GNU MP Library is distributed in the hope that it will be useful, but 17 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 18 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 19 License for more details. 20 21 You should have received a copy of the GNU Lesser General Public License 22 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 23 24 #include "gmp.h" 25 #include "gmp-impl.h" 26 #include "longlong.h" 27 28 29 #if GMP_NAIL_BITS != 0 30 you lose 31 #endif 32 33 /* For testing purposes, define our own mpn_addmul_2 if there is none already 34 available. */ 35 #ifndef HAVE_NATIVE_mpn_addmul_2 36 mp_limb_t 37 mpn_addmul_2 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_srcptr vp) 38 { 39 rp[n] = mpn_addmul_1 (rp, up, n, vp[0]); 40 return mpn_addmul_1 (rp + 1, up, n, vp[1]); 41 } 42 #endif 43 44 #if defined (__GNUC__) && defined (__ia64) && W_TYPE_SIZE == 64 45 #define umul2low(ph, pl, uh, ul, vh, vl) \ 46 do { \ 47 mp_limb_t _ph, _pl; \ 48 __asm__ ("xma.hu %0 = %3, %5, f0\n\t" \ 49 "xma.l %1 = %3, %5, f0\n\t" \ 50 ";;\n\t" \ 51 "xma.l %0 = %3, %4, %0\n\t" \ 52 ";;\n\t" \ 53 "xma.l %0 = %2, %5, %0" \ 54 : "=&f" (ph), "=&f" (pl) \ 55 : "f" (uh), "f" (ul), "f" (vh), "f" (vl)); \ 56 } while (0) 57 #endif 58 59 #ifndef umul2low 60 #define umul2low(ph, pl, uh, ul, vh, vl) \ 61 do { \ 62 mp_limb_t _ph, _pl; \ 63 umul_ppmm (_ph, _pl, ul, vl); \ 64 (ph) = _ph + (ul) * (vh) + (uh) * (vl); \ 65 (pl) = _pl; \ 66 } while (0) 67 #endif 68 69 void 70 mpn_redc_2 (mp_ptr rp, mp_ptr up, mp_srcptr mp, mp_size_t n, mp_srcptr mip) 71 { 72 mp_limb_t q[2]; 73 mp_size_t j; 74 mp_limb_t upn; 75 mp_limb_t cy; 76 77 ASSERT (n > 0); 78 ASSERT_MPN (up, 2*n); 79 80 if ((n & 1) != 0) 81 { 82 up[0] = mpn_addmul_1 (up, mp, n, (up[0] * mip[0]) & GMP_NUMB_MASK); 83 up++; 84 } 85 86 for (j = n - 2; j >= 0; j -= 2) 87 { 88 umul2low (q[1], q[0], mip[1], mip[0], up[1], up[0]); 89 upn = up[n]; /* mpn_addmul_2 overwrites this */ 90 up[1] = mpn_addmul_2 (up, mp, n, q); 91 up[0] = up[n]; 92 up[n] = upn; 93 up += 2; 94 } 95 cy = mpn_add_n (rp, up, up - n, n); 96 if (cy != 0) 97 mpn_sub_n (rp, rp, mp, n); 98 } 99