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https://github.com/ClickHouse/ClickHouse.git
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130 lines
2.4 KiB
C++
130 lines
2.4 KiB
C++
/// Taken from SMHasher.
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#pragma once
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#include <cstdint>
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//-----------------------------------------------------------------------------
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// Xorshift RNG based on code by George Marsaglia
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// http://en.wikipedia.org/wiki/Xorshift
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struct Rand
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{
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uint32_t x;
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uint32_t y;
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uint32_t z;
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uint32_t w;
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Rand()
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{
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reseed(static_cast<uint32_t>(0));
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}
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explicit Rand(uint32_t seed)
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{
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reseed(seed);
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}
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void reseed(uint32_t seed)
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{
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x = 0x498b3bc5 ^ seed;
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y = 0;
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z = 0;
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w = 0;
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for (int i = 0; i < 10; i++)
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mix();
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}
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void reseed(uint64_t seed)
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{
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x = 0x498b3bc5 ^ static_cast<uint32_t>(seed >> 0);
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y = 0x5a05089a ^ static_cast<uint32_t>(seed >> 32);
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z = 0;
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w = 0;
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for (int i = 0; i < 10; i++)
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mix();
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}
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//-----------------------------------------------------------------------------
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void mix(void)
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{
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uint32_t t = x ^ (x << 11);
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x = y;
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y = z;
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z = w;
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w = w ^ (w >> 19) ^ t ^ (t >> 8);
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}
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uint32_t rand_u32(void)
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{
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mix();
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return x;
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}
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uint64_t rand_u64(void)
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{
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mix();
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uint64_t a = x;
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uint64_t b = y;
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return (a << 32) | b;
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}
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void rand_p(void * blob, int bytes)
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{
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uint32_t * blocks = reinterpret_cast<uint32_t *>(blob);
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while (bytes >= 4)
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{
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blocks[0] = rand_u32();
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blocks++;
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bytes -= 4;
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}
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uint8_t * tail = reinterpret_cast<uint8_t *>(blocks);
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for (int i = 0; i < bytes; i++)
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{
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tail[i] = static_cast<uint8_t>(rand_u32());
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}
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}
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};
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//-----------------------------------------------------------------------------
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extern Rand g_rand1;
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inline uint32_t rand_u32(void)
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{
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return g_rand1.rand_u32();
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}
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inline uint64_t rand_u64(void)
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{
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return g_rand1.rand_u64();
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}
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inline void rand_p(void * blob, int bytes)
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{
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uint32_t * blocks = static_cast<uint32_t *>(blob);
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while (bytes >= 4)
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{
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*blocks++ = rand_u32();
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bytes -= 4;
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}
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uint8_t * tail = reinterpret_cast<uint8_t *>(blocks);
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for (int i = 0; i < bytes; i++)
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{
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tail[i] = static_cast<uint8_t>(rand_u32());
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}
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}
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//-----------------------------------------------------------------------------
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