X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/pfilt.c?ds=sidebyside diff --git a/pfilt.c b/pfilt.c deleted file mode 100644 index ae99a9b6..00000000 --- a/pfilt.c +++ /dev/null @@ -1,329 +0,0 @@ -/* -*-c-*- - * - * $Id: pfilt.c,v 1.6 2004/04/08 01:36:15 mdw Exp $ - * - * Finding and testing prime numbers - * - * (c) 1999 Straylight/Edgeware - */ - -/*----- Licensing notice --------------------------------------------------* - * - * This file is part of Catacomb. - * - * Catacomb is free software; you can redistribute it and/or modify - * it under the terms of the GNU Library General Public License as - * published by the Free Software Foundation; either version 2 of the - * License, or (at your option) any later version. - * - * Catacomb is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU Library General Public License for more details. - * - * You should have received a copy of the GNU Library General Public - * License along with Catacomb; if not, write to the Free - * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, - * MA 02111-1307, USA. - */ - -/*----- Header files ------------------------------------------------------*/ - -#include "mp.h" -#include "mpint.h" -#include "pfilt.h" -#include "pgen.h" -#include "primetab.h" - -/*----- Main code ---------------------------------------------------------*/ - -/* --- @smallenough@ --- * - * - * Arguments: @mp *m@ = integer to test - * - * Returns: One of the @PGEN@ result codes. - * - * Use: Assuming that @m@ has been tested by trial division on every - * prime in the small-primes array, this function will return - * @PGEN_DONE@ if the number is less than the square of the - * largest small prime. - */ - -static int smallenough(mp *m) -{ - static mp *max = 0; - int rc = PGEN_TRY; - - if (!max) { - max = mp_fromuint(MP_NEW, MAXPRIME); - max = mp_sqr(max, max); - max->a->n--; /* Permanent allocation */ - } - if (MP_CMP(m, <=, MP_ONE)) - rc = PGEN_FAIL; - else if (MP_CMP(m, <, max)) - rc = PGEN_DONE; - return (rc); -} - -/* --- @pfilt_smallfactor@ --- * - * - * Arguments: @mp *m@ = integer to test - * - * Returns: One of the @PGEN@ result codes. - * - * Use: Tests a number by dividing by a number of small primes. This - * is a useful first step if you're testing random primes; for - * sequential searches, @pfilt_create@ works better. - */ - -int pfilt_smallfactor(mp *m) -{ - int rc = PGEN_TRY; - int i; - size_t sz = MP_LEN(m); - mparena *a = m->a ? m->a : MPARENA_GLOBAL; - mpw *v = mpalloc(a, sz); - - /* --- Fill in the residues --- */ - - for (i = 0; i < NPRIME; i++) { - if (!mpx_udivn(v, v + sz, m->v, m->vl, primetab[i])) { - if (MP_LEN(m) == 1 && m->v[0] == primetab[i]) - rc = PGEN_DONE; - else - rc = PGEN_FAIL; - break; - } - } - - /* --- Check for small primes --- */ - - if (rc == PGEN_TRY) - rc = smallenough(m); - - /* --- Done --- */ - - mpfree(a, v); - return (rc); -} - -/* --- @pfilt_create@ --- * - * - * Arguments: @pfilt *p@ = pointer to prime filtering context - * @mp *m@ = pointer to initial number to test - * - * Returns: One of the @PGEN@ result codes. - * - * Use: Tests an initial number for primality by computing its - * residue modulo various small prime numbers. This is fairly - * quick, but not particularly certain. If a @PGEN_TRY@ - * result is returned, perform Rabin-Miller tests to confirm. - */ - -int pfilt_create(pfilt *p, mp *m) -{ - int rc = PGEN_TRY; - int i; - size_t sz = MP_LEN(m); - mparena *a = m->a ? m->a : MPARENA_GLOBAL; - mpw *v = mpalloc(a, sz); - - /* --- Take a copy of the number --- */ - - mp_shrink(m); - p->m = MP_COPY(m); - - /* --- Fill in the residues --- */ - - for (i = 0; i < NPRIME; i++) { - p->r[i] = mpx_udivn(v, v + sz, m->v, m->vl, primetab[i]); - if (!p->r[i] && rc == PGEN_TRY) { - if (MP_LEN(m) == 1 && m->v[0] == primetab[i]) - rc = PGEN_DONE; - else - rc = PGEN_FAIL; - } - } - - /* --- Check for small primes --- */ - - if (rc == PGEN_TRY) - rc = smallenough(m); - - /* --- Done --- */ - - mpfree(a, v); - return (rc); -} - -/* --- @pfilt_destroy@ --- * - * - * Arguments: @pfilt *p@ = pointer to prime filtering context - * - * Returns: --- - * - * Use: Discards a context and all the resources it holds. - */ - -void pfilt_destroy(pfilt *p) -{ - mp_drop(p->m); -} - -/* --- @pfilt_step@ --- * - * - * Arguments: @pfilt *p@ = pointer to prime filtering context - * @mpw step@ = how much to step the number - * - * Returns: One of the @PGEN@ result codes. - * - * Use: Steps a number by a small amount. Stepping is much faster - * than initializing with a new number. The test performed is - * the same simple one used by @primetab_create@, so @PGEN_TRY@ - * results should be followed up by a Rabin-Miller test. - */ - -int pfilt_step(pfilt *p, mpw step) -{ - int rc = PGEN_TRY; - int i; - - /* --- Add the step on to the number --- */ - - p->m = mp_split(p->m); - mp_ensure(p->m, MP_LEN(p->m) + 1); - mpx_uaddn(p->m->v, p->m->vl, step); - mp_shrink(p->m); - - /* --- Update the residue table --- */ - - for (i = 0; i < NPRIME; i++) { - p->r[i] = (p->r[i] + step) % primetab[i]; - if (!p->r[i] && rc == PGEN_TRY) { - if (MP_LEN(p->m) == 1 && p->m->v[0] == primetab[i]) - rc = PGEN_DONE; - else - rc = PGEN_FAIL; - } - } - - /* --- Check for small primes --- */ - - if (rc == PGEN_TRY) - rc = smallenough(p->m); - - /* --- Done --- */ - - return (rc); -} - -/* --- @pfilt_muladd@ --- * - * - * Arguments: @pfilt *p@ = destination prime filtering context - * @const pfilt *q@ = source prime filtering context - * @mpw m@ = number to multiply by - * @mpw a@ = number to add - * - * Returns: One of the @PGEN@ result codes. - * - * Use: Multiplies the number in a prime filtering context by a - * small value and then adds a small value. The destination - * should either be uninitialized or the same as the source. - * - * Common things to do include multiplying by 2 and adding 0 to - * turn a prime into a jump for finding other primes with @q@ as - * a factor of @p - 1@, or multiplying by 2 and adding 1. - */ - -int pfilt_muladd(pfilt *p, const pfilt *q, mpw m, mpw a) -{ - int rc = PGEN_TRY; - int i; - - /* --- Multiply the big number --- */ - - { - mp *d = mp_new(MP_LEN(q->m) + 2, q->m->f); - mpx_umuln(d->v, d->vl, q->m->v, q->m->vl, m); - mpx_uaddn(d->v, d->vl, a); - if (p == q) - mp_drop(p->m); - mp_shrink(d); - p->m = d; - } - - /* --- Gallivant through the residue table --- */ - - for (i = 0; i < NPRIME; i++) { - p->r[i] = (q->r[i] * m + a) % primetab[i]; - if (!p->r[i] && rc == PGEN_TRY) { - if (MP_LEN(p->m) == 1 && p->m->v[0] == primetab[i]) - rc = PGEN_DONE; - else - rc = PGEN_FAIL; - } - } - - /* --- Check for small primes --- */ - - if (rc == PGEN_TRY) - rc = smallenough(p->m); - - /* --- Finished --- */ - - return (rc); -} - -/* --- @pfilt_jump@ --- * - * - * Arguments: @pfilt *p@ = pointer to prime filtering context - * @const pfilt *j@ = pointer to another filtering context - * - * Returns: One of the @PGEN@ result codes. - * - * Use: Steps a number by a large amount. Even so, jumping is much - * faster than initializing a new number. The test peformed is - * the same simple one used by @primetab_create@, so @PGEN_TRY@ - * results should be followed up by a Rabin-Miller test. - * - * Note that the number stored in the @j@ context is probably - * better off being even than prime. The important thing is - * that all of the residues for the number have already been - * computed. - */ - -int pfilt_jump(pfilt *p, const pfilt *j) -{ - int rc = PGEN_TRY; - int i; - - /* --- Add the step on --- */ - - p->m = mp_add(p->m, p->m, j->m); - - /* --- Update the residue table --- */ - - for (i = 0; i < NPRIME; i++) { - p->r[i] = p->r[i] + j->r[i]; - if (p->r[i] > primetab[i]) - p->r[i] -= primetab[i]; - if (!p->r[i] && rc == PGEN_TRY) { - if (MP_LEN(p->m) == 1 && p->m->v[0] == primetab[i]) - rc = PGEN_DONE; - else - rc = PGEN_FAIL; - } - } - - /* --- Check for small primes --- */ - - if (rc == PGEN_TRY) - rc = smallenough(p->m); - - /* --- Done --- */ - - return (rc); -} - -/*----- That's all, folks -------------------------------------------------*/