/* Copyright 2012
* Kaz Kylheku <kaz@kylheku.com>
* Vancouver, Canada
* All rights reserved.
*
* BSD License:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wctype.h>
#include <assert.h>
#include <limits.h>
#include <stdarg.h>
#include <dirent.h>
#include <setjmp.h>
#include <wchar.h>
#include <limits.h>
#include <time.h>
#include "config.h"
#include "lib.h"
#include "unwind.h"
#include "gc.h"
#include "arith.h"
#include "rand.h"
#if SIZEOF_INT == 4
typedef unsigned int rand32_t;
#elif SIZEOF_LONG == 4
typedef unsigned long rand32_t;
#endif
/*
* The algorithm here is WELL 512.
* (Francois Panneton, Pierre L'Ecuyer.)
*/
struct random_state {
rand32_t state[16];
int cur;
};
val random_state;
val random_state_s;
static struct cobj_ops random_state_ops = {
cobj_equal_op,
cobj_print_op,
cobj_destroy_free_op,
cobj_mark_op,
cobj_hash_op
};
static val make_state(void)
{
struct random_state *r = (struct random_state *) chk_malloc(sizeof *r);
return cobj((mem_t *) r, random_state_s, &random_state_ops);
}
val random_state_p(val obj)
{
return typeof(obj) == random_state_s ? t : nil;
}
static rand32_t rand32(struct random_state *r)
{
#define RSTATE(r,i) ((r)->state[((r)->cur + i) % 16])
rand32_t s0 = RSTATE(r, 0);
rand32_t s9 = RSTATE(r, 9);
rand32_t s13 = RSTATE(r, 13);
rand32_t s15 = RSTATE(r, 15);
rand32_t r1 = s0 ^ (s0 << 16) ^ s13 ^ (s13 << 15);
rand32_t r2 = s9 ^ (s9 >> 11);
rand32_t ns0 = RSTATE(r, 0) = r1 ^ r2;
rand32_t ns15 = s15 ^ (s15 << 2) ^ r1 ^ (r1 << 18) ^ r2 ^ (r2 << 28) ^
((ns0 ^ (ns0 << 5)) & 0xda442d24ul);
RSTATE(r, 15) = ns15;
r->cur = (r->cur + 15) % 16;
return ns15;
#undef RSTATE
}
val make_random_state(val seed)
{
val rs = make_state();
int i;
struct random_state *r = (struct random_state *)
cobj_handle(rs, random_state_s);
r->cur = 0;
if (bignump(seed)) {
int i, dig, bit;
mp_int *m = mp(seed);
for (i = 0, dig = 0, bit = 0; i < 16 && dig < m->used; i++) {
r->state[i] = (m->dp[dig] >> bit) & 0xFFFFFFFFul;
bit += 32;
if (bit >= MP_DIGIT_BIT)
dig++, bit = 0;
}
for (; i < 16; i++) {
r->state[i] = 0xAAAAAAAA;
}
} else if (fixnump(seed)) {
cnum s = c_num(seed) & NUM_MAX;
memset(r->state, 0xAA, sizeof r->state);
r->state[0] = s & 0xFFFFFFFFul;
#if SIZEOF_PTR >= 8
r->state[1] = (s >> 32) & 0xFFFFFFFFul;
#elif SIZEOF_PTR >= 16
r->state[2] = (s >> 64) & 0xFFFFFFFFul;
r->state[3] = (s >> 96) & 0xFFFFFFFFul;
#endif
} else if (nullp(seed)) {
r->state[0] = (rand32_t) time(0);
r->state[1] = (rand32_t) clock();
memset(r->state + 2, 0xAA, sizeof r->state - 2 * sizeof r->state[0]);
} else if (random_state_p(seed)) {
struct random_state *rseed = (struct random_state *)
cobj_handle(seed, random_state_s);
*r = *rseed;
} else {
uw_throwf(error_s, lit("make-random-state: seed ~s is not a number"),
seed, nao);
}
for (i = 0; i < 8; i++)
(void) rand32(r);
return rs;
}
val random_fixnum(val state)
{
uses_or2;
struct random_state *r = (struct random_state *)
cobj_handle(or2(state, random_state),
random_state_s);
return num(rand32(r) & NUM_MAX);
}
val random(val state, val modulus)
{
uses_or2;
struct random_state *r = (struct random_state *)
cobj_handle(or2(state, random_state),
random_state_s);
if (bignump(modulus)) {
mp_int *m = mp(modulus);
int bits = mp_count_bits(m);
int rands_needed = (bits + 32 - 1) / 32;
int msb_rand_bits = bits % 32;
rand32_t msb_rand_mask = ((rand32_t) -1) >> (32 - msb_rand_bits);
val out = make_bignum();
mp_int *om = mp(out);
for (;;) {
int i;
for (i = 0; i < rands_needed; i++) {
rand32_t rnd = rand32(r);
#if MP_DIGIT_SIZE >= 4
if (i > 0)
mp_mul_2d(om, 32, om);
else
rnd &= msb_rand_mask;
mp_add_d(om, rnd, om);
#else
if (i > 0)
mp_mul_2d(om, 16, om);
else
rnd &= msb_rand_mask;
mp_add_d(om, rnd & 0xFFFF, om);
mp_mul_2d(om, 16, om);
mp_add_d(om, rnd >> 16, om);
#endif
}
if (mp_cmp(om, m) != MP_LT) {
mp_zero(om);
continue;
}
break;
}
return normalize(out);
} else if (fixnump(modulus)) {
cnum m = c_num(modulus);
int bits = highest_bit(m);
#if SIZEOF_PTR >= 8
int rands_needed = (bits + 32 - 1) / 32;
#endif
int msb_rand_bits = bits % 32;
rand32_t msb_rand_mask = ((rand32_t) -1) >> (32 - msb_rand_bits);
if (m <= 0)
goto invalid;
for (;;) {
cnum out = 0;
#if SIZEOF_PTR >= 8
int i;
for (i = 0; i < rands_needed; i++) {
rand32_t rnd = rand32(r);
out <<= 32;
if (i == 0)
rnd &= msb_rand_mask;
out |= rnd;
}
#else
out = rand32(r) & msb_rand_mask;
#endif
if (out >= m)
continue;
return num(out);
}
}
invalid:
uw_throwf(numeric_error_s, lit("random: invalid modulus ~s"),
modulus, nao);
}
val rnd(val modulus, val state)
{
return random(state, modulus);
}
void rand_init(void)
{
prot1(&random_state);
random_state_s = intern(lit("random-state"), user_package);
random_state = make_random_state(num(42));
}