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Diffstat (limited to 'lib/libc/stdlib/random.h')
| -rw-r--r-- | lib/libc/stdlib/random.h | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/lib/libc/stdlib/random.h b/lib/libc/stdlib/random.h new file mode 100644 index 000000000000..c7d4f2c18b77 --- /dev/null +++ b/lib/libc/stdlib/random.h @@ -0,0 +1,83 @@ +/*- + * Copyright 2020 Conrad Meyer <cem@FreeBSD.org>. All rights reserved. + * + * 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. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#pragma once + +/* + * For each of the currently supported random number generators, we have a + * break value on the amount of state information (you need at least this + * many bytes of state info to support this random number generator), a degree + * for the polynomial (actually a trinomial) that the R.N.G. is based on, and + * the separation between the two lower order coefficients of the trinomial. + */ +#define TYPE_0 0 /* linear congruential */ +#define BREAK_0 8 +#define DEG_0 0 +#define SEP_0 0 + +#define TYPE_1 1 /* x**7 + x**3 + 1 */ +#define BREAK_1 32 +#define DEG_1 7 +#define SEP_1 3 + +#define TYPE_2 2 /* x**15 + x + 1 */ +#define BREAK_2 64 +#define DEG_2 15 +#define SEP_2 1 + +#define TYPE_3 3 /* x**31 + x**3 + 1 */ +#define BREAK_3 128 +#define DEG_3 31 +#define SEP_3 3 + +#define TYPE_4 4 /* x**63 + x + 1 */ +#define BREAK_4 256 +#define DEG_4 63 +#define SEP_4 1 + +/* + * Array versions of the above information to make code run faster -- + * relies on fact that TYPE_i == i. + */ +#define MAX_TYPES 5 /* max number of types above */ + +/* A full instance of the random(3) generator. */ +struct __random_state { + uint32_t *rst_fptr; + uint32_t *rst_rptr; + uint32_t *rst_state; + int rst_type; + int rst_deg; + int rst_sep; + uint32_t *rst_end_ptr; + /* Flexible array member must be last. */ + uint32_t rst_randtbl[]; +}; + +struct __random_state *allocatestate(unsigned type); +int initstate_r(struct __random_state *, unsigned, uint32_t *, size_t); +long random_r(struct __random_state *); +void srandom_r(struct __random_state *, unsigned); +void srandomdev_r(struct __random_state *); |