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|
// file kernel/x/c/random.c: random extensible integers
/*-----------------------------------------------------------------------+
| Copyright 2005-2006, Michel Quercia (michel.quercia@prepas.org) |
| |
| This file is part of Numerix. Numerix is free software; you can |
| redistribute it and/or modify it under the terms of the GNU Lesser |
| General Public License as published by the Free Software Foundation; |
| either version 2.1 of the License, or (at your option) any later |
| version. |
| |
| The Numerix Library 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU MP Library; see the file COPYING. If not, |
| write to the Free Software Foundation, Inc., 59 Temple Place - |
| Suite 330, Boston, MA 02111-1307, USA. |
+-----------------------------------------------------------------------+
| |
| Nombres alatoires |
| |
+-----------------------------------------------------------------------*/
#include <time.h>
/* initialisation du gnrateur alatoire */
#ifdef c_api
void xx(random_init)(long n) {
if (n == 0) n = time(NULL);
srandom(n);
}
#elif defined(caml_api) || defined(ocaml_api)
value xx(random_init)(long n) {
n = Long_val(n);
if (n == 0) n = time(NULL);
srandom(n);
return Val_unit;
}
#endif /* api */
/* ---------------------------------------- Nombre alatoire
entre :
_a = NULL ou pointeur vers un entier extensible
n = longueur >= 0
mode = long C
sortie :
a <- entier alatoire entre -2^n-1 et 2^n-1
les bits 0 et 1 de mode restreignent la plage alatoire de la manire suivante :
b0=0 => le signe est forc >= 0
b1=1 => le bit de rang n-1 est forc = 1 si n > 0
si _a != NULL, *_a <- a
retourne a
erreur :
NEGATIVE_SIZE si n < 0
*/
xint xx(private_random)(xint *_a, long n, long mode) {
long l,s;
xint a;
xx_push_roots_1(_a);
#ifdef caml_api
#define _a __lr._a
#endif
#if defined(caml_api) || defined(ocaml_api)
n = Long_val(n);
#endif
if (n < 0) xx(failwith)(NEGATIVE_SIZE);
if (n == 0) {
a = xx(enlarge)(_a,0);
a->hd = 0;
xx_update_and_return(_a,a);
}
/* tire la valeur absolue au hasard */
l = (n + HW-1)/HW; n %= HW;
a = xx(enlarge)(_a,l);
xn(random)(a->val,l);
/* signe */
if (mode&1) s = (random()&1) ? SIGN_m : 0;
else s = 0;
/* corrige le chiffre de poids fort */
if (n) a->val[l-1] &= ((chiffre)1 << n) - 1;
if (mode&2) a->val[l-1] |= (n) ? (chiffre)1 << (n-1) : BASE_2;
/* longueur et signe du rsultat */
xx(make_head)(a,l,s);
xx_update_and_return(_a,a);
#undef _a
}
#if defined(caml_api) || defined(ocaml_api)
/*
nrandom(n) -> [0, 2^n[
zrandom(n) -> ]-2^n, 2^n[
nrandom1(n) -> [2^(n-1), 2^n[
zrandom1(n) -> ]-2^n, -2^(n-1)] U [2^(n-1), 2^n[
*/
xint xx(nrandom) (xint *_a, long n) {return xx(private_random)(_a,n,0);}
xint xx(zrandom) (xint *_a, long n) {return xx(private_random)(_a,n,1);}
xint xx(nrandom1)(xint *_a, long n) {return xx(private_random)(_a,n,2);}
xint xx(zrandom1)(xint *_a, long n) {return xx(private_random)(_a,n,3);}
xint xx(f_nrandom) (long n) {return xx(private_random)(xx_null,n,0);}
xint xx(f_zrandom) (long n) {return xx(private_random)(xx_null,n,1);}
xint xx(f_nrandom1) (long n) {return xx(private_random)(xx_null,n,2);}
xint xx(f_zrandom1) (long n) {return xx(private_random)(xx_null,n,3);}
#endif /* defined(caml_api) || defined(ocaml_api) */
|
