toom54_mul.c revision 1.1.1.1
1/* Implementation of the algorithm for Toom-Cook 4.5-way. 2 3 Contributed to the GNU project by Marco Bodrato. 4 5 THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY 6 SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST 7 GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE. 8 9Copyright 2009, 2012 Free Software Foundation, Inc. 10 11This file is part of the GNU MP Library. 12 13The GNU MP Library is free software; you can redistribute it and/or modify 14it under the terms of the GNU Lesser General Public License as published by 15the Free Software Foundation; either version 3 of the License, or (at your 16option) any later version. 17 18The GNU MP Library is distributed in the hope that it will be useful, but 19WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 20or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 21License for more details. 22 23You should have received a copy of the GNU Lesser General Public License 24along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 25 26#include "gmp.h" 27#include "gmp-impl.h" 28 29 30/* Toom-4.5, the splitting 5x4 unbalanced version. 31 Evaluate in: infinity, +4, -4, +2, -2, +1, -1, 0. 32 33 <--s-><--n--><--n--><--n--><--n--> 34 ____ ______ ______ ______ ______ 35 |_a4_|__a3__|__a2__|__a1__|__a0__| 36 |b3_|__b2__|__b1__|__b0__| 37 <-t-><--n--><--n--><--n--> 38 39*/ 40#define TOOM_54_MUL_N_REC(p, a, b, n, ws) \ 41 do { mpn_mul_n (p, a, b, n); \ 42 } while (0) 43 44#define TOOM_54_MUL_REC(p, a, na, b, nb, ws) \ 45 do { mpn_mul (p, a, na, b, nb); \ 46 } while (0) 47 48void 49mpn_toom54_mul (mp_ptr pp, 50 mp_srcptr ap, mp_size_t an, 51 mp_srcptr bp, mp_size_t bn, mp_ptr scratch) 52{ 53 mp_size_t n, s, t; 54 int sign; 55 56 /***************************** decomposition *******************************/ 57#define a4 (ap + 4 * n) 58#define b3 (bp + 3 * n) 59 60 ASSERT (an >= bn); 61 n = 1 + (4 * an >= 5 * bn ? (an - 1) / (size_t) 5 : (bn - 1) / (size_t) 4); 62 63 s = an - 4 * n; 64 t = bn - 3 * n; 65 66 ASSERT (0 < s && s <= n); 67 ASSERT (0 < t && t <= n); 68 /* Required by mpn_toom_interpolate_8pts. */ 69 ASSERT ( s + t >= n ); 70 ASSERT ( s + t > 4); 71 ASSERT ( n > 2); 72 73#define r8 pp /* 2n */ 74#define r7 scratch /* 3n+1 */ 75#define r5 (pp + 3*n) /* 3n+1 */ 76#define v0 (pp + 3*n) /* n+1 */ 77#define v1 (pp + 4*n+1) /* n+1 */ 78#define v2 (pp + 5*n+2) /* n+1 */ 79#define v3 (pp + 6*n+3) /* n+1 */ 80#define r3 (scratch + 3 * n + 1) /* 3n+1 */ 81#define r1 (pp + 7*n) /* s+t <= 2*n */ 82#define ws (scratch + 6 * n + 2) /* ??? */ 83 84 /* Alloc also 3n+1 limbs for ws... mpn_toom_interpolate_8pts may 85 need all of them, when DO_mpn_sublsh_n usea a scratch */ 86 /********************** evaluation and recursive calls *********************/ 87 /* $\pm4$ */ 88 sign = mpn_toom_eval_pm2exp (v2, v0, 4, ap, n, s, 2, pp) 89 ^ mpn_toom_eval_pm2exp (v3, v1, 3, bp, n, t, 2, pp); 90 TOOM_54_MUL_N_REC(pp, v0, v1, n + 1, ws); /* A(-4)*B(-4) */ 91 TOOM_54_MUL_N_REC(r3, v2, v3, n + 1, ws); /* A(+4)*B(+4) */ 92 mpn_toom_couple_handling (r3, 2*n+1, pp, sign, n, 2, 4); 93 94 /* $\pm1$ */ 95 sign = mpn_toom_eval_pm1 (v2, v0, 4, ap, n, s, pp) 96 ^ mpn_toom_eval_dgr3_pm1 (v3, v1, bp, n, t, pp); 97 TOOM_54_MUL_N_REC(pp, v0, v1, n + 1, ws); /* A(-1)*B(-1) */ 98 TOOM_54_MUL_N_REC(r7, v2, v3, n + 1, ws); /* A(1)*B(1) */ 99 mpn_toom_couple_handling (r7, 2*n+1, pp, sign, n, 0, 0); 100 101 /* $\pm2$ */ 102 sign = mpn_toom_eval_pm2 (v2, v0, 4, ap, n, s, pp) 103 ^ mpn_toom_eval_dgr3_pm2 (v3, v1, bp, n, t, pp); 104 TOOM_54_MUL_N_REC(pp, v0, v1, n + 1, ws); /* A(-2)*B(-2) */ 105 TOOM_54_MUL_N_REC(r5, v2, v3, n + 1, ws); /* A(+2)*B(+2) */ 106 mpn_toom_couple_handling (r5, 2*n+1, pp, sign, n, 1, 2); 107 108 /* A(0)*B(0) */ 109 TOOM_54_MUL_N_REC(pp, ap, bp, n, ws); 110 111 /* Infinity */ 112 if (s > t) { 113 TOOM_54_MUL_REC(r1, a4, s, b3, t, ws); 114 } else { 115 TOOM_54_MUL_REC(r1, b3, t, a4, s, ws); 116 }; 117 118 mpn_toom_interpolate_8pts (pp, n, r3, r7, s + t, ws); 119 120#undef a4 121#undef b3 122#undef r1 123#undef r3 124#undef r5 125#undef v0 126#undef v1 127#undef v2 128#undef v3 129#undef r7 130#undef r8 131#undef ws 132} 133