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75 lines
1.2 KiB
75 lines
1.2 KiB
3 months ago
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/*
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* UCW Library -- Unbiased Random Numbers
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*
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* (c) 1998--2006 Martin Mares <mj@ucw.cz>
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* (c) 2020 Pavel Charvat <pchar@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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#include <ucw/lib.h>
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#include <ucw/random.h>
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#include <stdlib.h>
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/* We expect the random generator in libc to give at least 30 bits of randomness */
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COMPILE_ASSERT(RAND_MAX_RANGE_TEST, RAND_MAX >= (1 << 30)-1);
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void
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random_set_seed(uint seed)
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{
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srandom(seed);
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}
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uint
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random_gen_seed(void)
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{
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uint seed = fastrand_gen_seed_value();
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random_set_seed(seed);
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return seed;
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}
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uint
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random_u32(void)
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{
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return (random() & 0xffff) | ((random() & 0xffff) << 16);
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}
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uint
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random_max(uint max)
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{
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uint r, l;
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ASSERT(max <= (1 << 30));
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l = (RAND_MAX + 1U) - ((RAND_MAX + 1U) % max);
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do
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r = random();
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while (r >= l);
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return r % max;
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}
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u64
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random_u64(void)
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{
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return
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((u64)(random() & 0xffff) << 48) |
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((u64)(random() & 0xffffff) << 24) |
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(random() & 0xffffff);
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}
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u64
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random_max_u64(u64 max)
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{
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if (max < (1 << 30))
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return random_max(max);
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u64 r, l, m;
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m = 0xffffffffffffffff;
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l = m - (m % max);
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do
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r = random_u64();
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while (r >= l);
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return r % max;
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}
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