1 /* mpn_submul_1 -- multiply the N long limb vector pointed to by UP by VL, 2 subtract the N least significant limbs of the product from the limb 3 vector pointed to by RP. Return the most significant limb of the 4 product, adjusted for carry-out from the subtraction. 5 6 Copyright 1992, 1993, 1994, 1996, 2000, 2002, 2004 Free Software Foundation, 7 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 31 mp_limb_t 32 mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl) 33 { 34 mp_limb_t ul, cl, hpl, lpl, rl; 35 36 ASSERT (n >= 1); 37 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n)); 38 39 cl = 0; 40 do 41 { 42 ul = *up++; 43 umul_ppmm (hpl, lpl, ul, vl); 44 45 lpl += cl; 46 cl = (lpl < cl) + hpl; 47 48 rl = *rp; 49 lpl = rl - lpl; 50 cl += lpl > rl; 51 *rp++ = lpl; 52 } 53 while (--n != 0); 54 55 return cl; 56 } 57 58 #endif 59 60 #if GMP_NAIL_BITS == 1 61 62 mp_limb_t 63 mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl) 64 { 65 mp_limb_t shifted_vl, ul, rl, lpl, hpl, prev_hpl, cl, xl, c1, c2, c3; 66 67 ASSERT (n >= 1); 68 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n)); 69 ASSERT_MPN (rp, n); 70 ASSERT_MPN (up, n); 71 ASSERT_LIMB (vl); 72 73 shifted_vl = vl << GMP_NAIL_BITS; 74 cl = 0; 75 prev_hpl = 0; 76 do 77 { 78 ul = *up++; 79 rl = *rp; 80 umul_ppmm (hpl, lpl, ul, shifted_vl); 81 lpl >>= GMP_NAIL_BITS; 82 SUBC_LIMB (c1, xl, rl, prev_hpl); 83 SUBC_LIMB (c2, xl, xl, lpl); 84 SUBC_LIMB (c3, xl, xl, cl); 85 cl = c1 + c2 + c3; 86 *rp++ = xl; 87 prev_hpl = hpl; 88 } 89 while (--n != 0); 90 91 return prev_hpl + cl; 92 } 93 94 #endif 95 96 #if GMP_NAIL_BITS >= 2 97 98 mp_limb_t 99 mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl) 100 { 101 mp_limb_t shifted_vl, ul, rl, lpl, hpl, prev_hpl, xw, cl, xl; 102 103 ASSERT (n >= 1); 104 ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n)); 105 ASSERT_MPN (rp, n); 106 ASSERT_MPN (up, n); 107 ASSERT_LIMB (vl); 108 109 shifted_vl = vl << GMP_NAIL_BITS; 110 cl = 0; 111 prev_hpl = 0; 112 do 113 { 114 ul = *up++; 115 rl = *rp; 116 umul_ppmm (hpl, lpl, ul, shifted_vl); 117 lpl >>= GMP_NAIL_BITS; 118 xw = rl - (prev_hpl + lpl) + cl; 119 cl = (mp_limb_signed_t) xw >> GMP_NUMB_BITS; /* FIXME: non-portable */ 120 xl = xw & GMP_NUMB_MASK; 121 *rp++ = xl; 122 prev_hpl = hpl; 123 } 124 while (--n != 0); 125 126 return prev_hpl - cl; 127 } 128 129 #endif 130