1 /* Implementation of the multiplication algorithm for Toom-Cook 8.5-way.
3 Contributed to the GNU project by Marco Bodrato.
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.
9 Copyright 2009, 2010 Free Software Foundation, Inc.
11 This file is part of the GNU MP Library.
13 The GNU MP Library is free software; you can redistribute it and/or modify
14 it under the terms of the GNU Lesser General Public License as published by
15 the Free Software Foundation; either version 3 of the License, or (at your
16 option) any later version.
18 The GNU MP Library is distributed in the hope that it will be useful, but
19 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
20 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
21 License for more details.
23 You should have received a copy of the GNU Lesser General Public License
24 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
31 #if GMP_NUMB_BITS < 29
32 #error Not implemented.
35 #if GMP_NUMB_BITS < 43
36 #define BIT_CORRECTION 1
37 #define CORRECTION_BITS GMP_NUMB_BITS
39 #define BIT_CORRECTION 0
40 #define CORRECTION_BITS 0
44 #if TUNE_PROGRAM_BUILD
45 #define MAYBE_mul_basecase 1
46 #define MAYBE_mul_toom22 1
47 #define MAYBE_mul_toom33 1
48 #define MAYBE_mul_toom44 1
49 #define MAYBE_mul_toom8h 1
51 #define MAYBE_mul_basecase \
52 (MUL_TOOM8H_THRESHOLD < 8 * MUL_TOOM22_THRESHOLD)
53 #define MAYBE_mul_toom22 \
54 (MUL_TOOM8H_THRESHOLD < 8 * MUL_TOOM33_THRESHOLD)
55 #define MAYBE_mul_toom33 \
56 (MUL_TOOM8H_THRESHOLD < 8 * MUL_TOOM44_THRESHOLD)
57 #define MAYBE_mul_toom44 \
58 (MUL_TOOM8H_THRESHOLD < 8 * MUL_TOOM6H_THRESHOLD)
59 #define MAYBE_mul_toom8h \
60 (MUL_FFT_THRESHOLD >= 8 * MUL_TOOM8H_THRESHOLD)
63 #define TOOM8H_MUL_N_REC(p, a, b, n, ws) \
65 if (MAYBE_mul_basecase \
66 && BELOW_THRESHOLD (n, MUL_TOOM22_THRESHOLD)) \
67 mpn_mul_basecase (p, a, n, b, n); \
68 else if (MAYBE_mul_toom22 \
69 && BELOW_THRESHOLD (n, MUL_TOOM33_THRESHOLD)) \
70 mpn_toom22_mul (p, a, n, b, n, ws); \
71 else if (MAYBE_mul_toom33 \
72 && BELOW_THRESHOLD (n, MUL_TOOM44_THRESHOLD)) \
73 mpn_toom33_mul (p, a, n, b, n, ws); \
74 else if (MAYBE_mul_toom44 \
75 && BELOW_THRESHOLD (n, MUL_TOOM6H_THRESHOLD)) \
76 mpn_toom44_mul (p, a, n, b, n, ws); \
77 else if (! MAYBE_mul_toom8h \
78 || BELOW_THRESHOLD (n, MUL_TOOM8H_THRESHOLD)) \
79 mpn_toom6h_mul (p, a, n, b, n, ws); \
81 mpn_toom8h_mul (p, a, n, b, n, ws); \
84 #define TOOM8H_MUL_REC(p, a, na, b, nb, ws) \
85 do { mpn_mul (p, a, na, b, nb); \
88 /* Toom-8.5 , compute the product {pp,an+bn} <- {ap,an} * {bp,bn}
89 With: an >= bn >= 86, an*5 < bn * 11.
90 It _may_ work with bn<=?? and bn*?? < an*? < bn*??
92 Evaluate in: infinity, +8,-8,+4,-4,+2,-2,+1,-1,+1/2,-1/2,+1/4,-1/4,+1/8,-1/8,0.
94 /* Estimate on needed scratch:
95 S(n) <= (n+7)\8*13+5+MAX(S((n+7)\8),1+2*(n+7)\8),
96 since n>80; S(n) <= ceil(log(n/10)/log(8))*(13+5)+n*15\8 < n*15\8 + lg2(n)*6
100 mpn_toom8h_mul (mp_ptr pp,
101 mp_srcptr ap, mp_size_t an,
102 mp_srcptr bp, mp_size_t bn, mp_ptr scratch)
108 /***************************** decomposition *******************************/
111 /* Can not handle too small operands */
113 /* Can not handle too much unbalancement */
114 ASSERT (an*4 <= bn*13);
115 ASSERT (GMP_NUMB_BITS > 12*3 || an*4 <= bn*12);
116 ASSERT (GMP_NUMB_BITS > 11*3 || an*5 <= bn*11);
117 ASSERT (GMP_NUMB_BITS > 10*3 || an*6 <= bn*10);
118 ASSERT (GMP_NUMB_BITS > 9*3 || an*7 <= bn* 9);
120 /* Limit num/den is a rational number between
121 (16/15)^(log(6)/log(2*6-1)) and (16/15)^(log(8)/log(2*8-1)) */
122 #define LIMIT_numerator (21)
123 #define LIMIT_denominat (20)
125 if (LIKELY (an == bn) || an * (LIMIT_denominat>>1) < LIMIT_numerator * (bn>>1) ) /* is 8*... < 8*... */
128 n = 1 + ((an - 1)>>3);
135 if (an * 13 < 16 * bn) /* (an*7*LIMIT_numerator<LIMIT_denominat*9*bn) */
137 else if (GMP_NUMB_BITS <= 9*3 ||
138 an *(LIMIT_denominat>>1) < (LIMIT_numerator/7*9) * (bn>>1))
140 else if (an * 10 < 33 * (bn>>1)) /* (an*3*LIMIT_numerator<LIMIT_denominat*5*bn) */
142 else if (GMP_NUMB_BITS <= 10*3 ||
143 an * (LIMIT_denominat/5) < (LIMIT_numerator/3) * bn)
145 else if (an * 6 < 13 * bn) /*(an * 5 * LIMIT_numerator < LIMIT_denominat *11 * bn)*/
147 else if (GMP_NUMB_BITS <= 11*3 ||
150 else if (an *(LIMIT_numerator/3) < LIMIT_denominat * bn ) /* is 4*... <12*... */
152 else if (GMP_NUMB_BITS <= 12*3 ||
153 an * 9 < 28 * bn ) /* is 4*... <12*... */
159 n = 1 + (q * an >= p * bn ? (an - 1) / (size_t) p : (bn - 1) / (size_t) q);
165 if(half) { /* Recover from badly chosen splitting */
166 if (s<1) {p--; s+=n; half=0;}
167 else if (t<1) {q--; t+=n; half=0;}
170 #undef LIMIT_numerator
171 #undef LIMIT_denominat
173 ASSERT (0 < s && s <= n);
174 ASSERT (0 < t && t <= n);
175 ASSERT (half || s + t > 3);
178 #define r6 (pp + 3 * n) /* 3n+1 */
179 #define r4 (pp + 7 * n) /* 3n+1 */
180 #define r2 (pp +11 * n) /* 3n+1 */
181 #define r0 (pp +15 * n) /* s+t <= 2*n */
182 #define r7 (scratch) /* 3n+1 */
183 #define r5 (scratch + 3 * n + 1) /* 3n+1 */
184 #define r3 (scratch + 6 * n + 2) /* 3n+1 */
185 #define r1 (scratch + 9 * n + 3) /* 3n+1 */
186 #define v0 (pp +11 * n) /* n+1 */
187 #define v1 (pp +12 * n+1) /* n+1 */
188 #define v2 (pp +13 * n+2) /* n+1 */
189 #define v3 (scratch +12 * n + 4) /* n+1 */
190 #define wsi (scratch +12 * n + 4) /* 3n+1 */
191 #define wse (scratch +13 * n + 5) /* 2n+1 */
193 /* Alloc also 3n+1 limbs for wsi... toom_interpolate_16pts may
195 /* if (scratch == NULL) */
196 /* scratch = TMP_SALLOC_LIMBS(mpn_toom8_sqr_itch(n * 8)); */
197 ASSERT (15 * n + 6 <= mpn_toom8h_mul_itch (an, bn));
198 ASSERT (15 * n + 6 <= mpn_toom8_sqr_itch (n * 8));
200 /********************** evaluation and recursive calls *********************/
203 sign = mpn_toom_eval_pm2rexp (v2, v0, p, ap, n, s, 3, pp) ^
204 mpn_toom_eval_pm2rexp (v3, v1, q, bp, n, t, 3, pp);
205 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-1/8)*B(-1/8)*8^. */
206 TOOM8H_MUL_N_REC(r7, v2, v3, n + 1, wse); /* A(+1/8)*B(+1/8)*8^. */
207 mpn_toom_couple_handling (r7, 2 * n + 1 + BIT_CORRECTION, pp, sign, n, 3*(1+half), 3*(half));
210 sign = mpn_toom_eval_pm2rexp (v2, v0, p, ap, n, s, 2, pp) ^
211 mpn_toom_eval_pm2rexp (v3, v1, q, bp, n, t, 2, pp);
212 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-1/4)*B(-1/4)*4^. */
213 TOOM8H_MUL_N_REC(r5, v2, v3, n + 1, wse); /* A(+1/4)*B(+1/4)*4^. */
214 mpn_toom_couple_handling (r5, 2 * n + 1, pp, sign, n, 2*(1+half), 2*(half));
217 sign = mpn_toom_eval_pm2 (v2, v0, p, ap, n, s, pp) ^
218 mpn_toom_eval_pm2 (v3, v1, q, bp, n, t, pp);
219 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-2)*B(-2) */
220 TOOM8H_MUL_N_REC(r3, v2, v3, n + 1, wse); /* A(+2)*B(+2) */
221 mpn_toom_couple_handling (r3, 2 * n + 1, pp, sign, n, 1, 2);
224 sign = mpn_toom_eval_pm2exp (v2, v0, p, ap, n, s, 3, pp) ^
225 mpn_toom_eval_pm2exp (v3, v1, q, bp, n, t, 3, pp);
226 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-8)*B(-8) */
227 TOOM8H_MUL_N_REC(r1, v2, v3, n + 1, wse); /* A(+8)*B(+8) */
228 mpn_toom_couple_handling (r1, 2 * n + 1 + BIT_CORRECTION, pp, sign, n, 3, 6);
231 sign = mpn_toom_eval_pm2rexp (v2, v0, p, ap, n, s, 1, pp) ^
232 mpn_toom_eval_pm2rexp (v3, v1, q, bp, n, t, 1, pp);
233 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-1/2)*B(-1/2)*2^. */
234 TOOM8H_MUL_N_REC(r6, v2, v3, n + 1, wse); /* A(+1/2)*B(+1/2)*2^. */
235 mpn_toom_couple_handling (r6, 2 * n + 1, pp, sign, n, 1+half, half);
238 sign = mpn_toom_eval_pm1 (v2, v0, p, ap, n, s, pp);
240 sign ^= mpn_toom_eval_dgr3_pm1 (v3, v1, bp, n, t, pp);
242 sign ^= mpn_toom_eval_pm1 (v3, v1, q, bp, n, t, pp);
243 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-1)*B(-1) */
244 TOOM8H_MUL_N_REC(r4, v2, v3, n + 1, wse); /* A(1)*B(1) */
245 mpn_toom_couple_handling (r4, 2 * n + 1, pp, sign, n, 0, 0);
248 sign = mpn_toom_eval_pm2exp (v2, v0, p, ap, n, s, 2, pp) ^
249 mpn_toom_eval_pm2exp (v3, v1, q, bp, n, t, 2, pp);
250 TOOM8H_MUL_N_REC(pp, v0, v1, n + 1, wse); /* A(-4)*B(-4) */
251 TOOM8H_MUL_N_REC(r2, v2, v3, n + 1, wse); /* A(+4)*B(+4) */
252 mpn_toom_couple_handling (r2, 2 * n + 1, pp, sign, n, 2, 4);
261 TOOM8H_MUL_N_REC(pp, ap, bp, n, wsi);
266 TOOM8H_MUL_REC(r0, ap + p * n, s, bp + q * n, t, wsi);
268 TOOM8H_MUL_REC(r0, bp + q * n, t, ap + p * n, s, wsi);
272 mpn_toom_interpolate_16pts (pp, r1, r3, r5, r7, n, s+t, half, wsi);
284 #undef TOOM8H_MUL_N_REC
285 #undef TOOM8H_MUL_REC
286 #undef MAYBE_mul_basecase
287 #undef MAYBE_mul_toom22
288 #undef MAYBE_mul_toom33
289 #undef MAYBE_mul_toom44
290 #undef MAYBE_mul_toom8h