1 /* mpn_mul -- Multiply two natural numbers.
3 THE HELPER FUNCTIONS IN THIS FILE (meaning everything except mpn_mul)
4 ARE INTERNAL FUNCTIONS WITH MUTABLE INTERFACES. IT IS ONLY SAFE TO REACH
5 THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST GUARANTEED
6 THAT THEY'LL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
9 Copyright (C) 1991, 1993, 1994, 1996, 1997, 1999, 2000 Free Software
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 2.1 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; see the file COPYING.LIB. If not, write to
26 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 MA 02111-1307, USA. */
32 /* Multiply the natural numbers u (pointed to by UP, with UN limbs) and v
33 (pointed to by VP, with VN limbs), and store the result at PRODP. The
34 result is UN + VN limbs. Return the most significant limb of the result.
36 NOTE: The space pointed to by PRODP is overwritten before finished with U
37 and V, so overlap is an error.
41 2. PRODP != UP and PRODP != VP, i.e. the destination must be distinct from
42 the multiplier and the multiplicand. */
46 mpn_sqr_n (mp_ptr prodp,
47 mp_srcptr up, mp_size_t un)
49 mpn_sqr_n (prodp, up, un)
55 if (un < KARATSUBA_SQR_THRESHOLD)
56 { /* plain schoolbook multiplication */
59 mpn_sqr_basecase (prodp, up, un);
61 else if (un < TOOM3_SQR_THRESHOLD)
62 { /* karatsuba multiplication */
66 tspace = (mp_ptr) TMP_ALLOC (2 * (un + BITS_PER_MP_LIMB) * BYTES_PER_MP_LIMB);
67 mpn_kara_sqr_n (prodp, up, un, tspace);
70 #if WANT_FFT || TUNE_PROGRAM_BUILD
71 else if (un < FFT_SQR_THRESHOLD)
75 { /* toom3 multiplication */
79 tspace = (mp_ptr) TMP_ALLOC (2 * (un + BITS_PER_MP_LIMB) * BYTES_PER_MP_LIMB);
80 mpn_toom3_sqr_n (prodp, up, un, tspace);
83 #if WANT_FFT || TUNE_PROGRAM_BUILD
86 /* schoenhage multiplication */
87 mpn_mul_fft_full (prodp, up, un, up, un);
94 mpn_mul (mp_ptr prodp,
95 mp_srcptr up, mp_size_t un,
96 mp_srcptr vp, mp_size_t vn)
98 mpn_mul (prodp, up, un, vp, vn)
109 if (up == vp && un == vn)
111 mpn_sqr_n (prodp, up, un);
112 return prodp[2 * un - 1];
115 if (vn < KARATSUBA_MUL_THRESHOLD)
116 { /* long multiplication */
117 mpn_mul_basecase (prodp, up, un, vp, vn);
118 return prodp[un + vn - 1];
121 mpn_mul_n (prodp, up, vp, vn);
135 /* Swap u's and v's. */
136 MPN_SRCPTR_SWAP (up,un, vp,vn);
139 ws = (mp_ptr) TMP_ALLOC (((vn >= KARATSUBA_MUL_THRESHOLD ? vn : un) + vn)
140 * BYTES_PER_MP_LIMB);
143 while (vn >= KARATSUBA_MUL_THRESHOLD)
145 mpn_mul_n (ws, up, vp, vn);
148 t += mpn_add_n (prodp, prodp, ws, l);
151 t = mpn_add_1 (prodp + l, ws + l, 2*vn - l, t);
157 c = mpn_add_n (prodp, prodp, ws, 2*vn);
158 t += mpn_add_1 (prodp + 2*vn, prodp + 2*vn, l - 2*vn, c);
166 /* Swap u's and v's. */
167 MPN_SRCPTR_SWAP (up,un, vp,vn);
173 mpn_mul_basecase (ws, up, un, vp, vn);
176 t += mpn_add_n (prodp, prodp, ws, l);
178 t = mpn_add_1 (prodp + l, ws + l, un + vn - l, t);
182 c = mpn_add_n (prodp, prodp, ws, un + vn);
183 t += mpn_add_1 (prodp + un + vn, prodp + un + vn, l - un - vn, c);
189 return prodp[un + vn - 1];