mirror of
https://libwebsockets.org/repo/libwebsockets
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81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/*
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* libwebsockets - small server side websockets and web server implementation
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*
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* Copyright (C) 2010 - 2021 Andy Green <andy@warmcat.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* After Public Domain implementations
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*
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* https://github.com/svaarala/duktape/tree/master/misc
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*/
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#include <private-lib-core.h>
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static inline uint64_t rol64(uint64_t x, int k)
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{
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return (x << k) | (x >> (64 - k));
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}
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uint64_t
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lws_xos(struct lws_xos *xos)
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{
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uint64_t *s = &xos->s[0];
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uint64_t const result = rol64(s[1] * 5, 7) * 9;
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uint64_t const c = s[1] << 17;
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s[2] ^= s[0];
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s[3] ^= s[1];
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s[1] ^= s[2];
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s[0] ^= s[3];
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s[2] ^= c;
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s[3] = rol64(s[3], 45);
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return result;
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}
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static uint64_t
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splitmix64(uint64_t *s)
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{
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uint64_t r = *s;
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*s = r + 0x9E3779B97F4A7C15ull;
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r = (r ^ (r >> 30)) * 0xBF58476D1CE4E5B9ull;
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r = (r ^ (r >> 27)) * 0x94D049BB133111EBull;
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return r ^ (r >> 31);
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}
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void
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lws_xos_init(struct lws_xos *xos, uint64_t seed)
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{
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int n;
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for (n = 0; n < 4; n++)
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xos->s[n] = splitmix64(&seed);
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}
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int
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lws_xos_percent(struct lws_xos *xos, int percent)
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{
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return (int)(lws_xos(xos) % 100) < percent;
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}
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