4f9d991449
History squashed from internal development. Internal history has commit hash: e27a0e485c44a5003a802de2661ce3b21e120316
72 lines
1.7 KiB
C++
72 lines
1.7 KiB
C++
#pragma once
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#include <cstdint>
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#include <cstdlib>
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namespace xoroshiro
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{
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namespace detail
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{
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template<typename STATE, typename RESULT, STATE A, STATE B, STATE C>
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class XorOshiro
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{
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private:
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static constexpr unsigned STATE_BITS = 8 * sizeof(STATE);
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static constexpr unsigned RESULT_BITS = 8 * sizeof(RESULT);
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static_assert(
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STATE_BITS >= RESULT_BITS,
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"STATE must have at least as many bits as RESULT");
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STATE x;
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STATE y;
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static inline STATE rotl(STATE x, STATE k)
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{
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return (x << k) | (x >> (STATE_BITS - k));
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}
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public:
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XorOshiro(STATE x_ = 5489, STATE y_ = 0) : x(x_), y(y_)
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{
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// If both zero, then this does not work
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if (x_ == 0 && y_ == 0)
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abort();
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next();
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}
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void set_state(STATE x_, STATE y_ = 0)
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{
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// If both zero, then this does not work
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if (x_ == 0 && y_ == 0)
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abort();
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x = x_;
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y = y_;
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next();
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}
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RESULT next()
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{
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STATE r = x + y;
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y ^= x;
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x = rotl(x, A) ^ y ^ (y << B);
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y = rotl(y, C);
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// If both zero, then this does not work
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if (x == 0 && y == 0)
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abort();
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return r >> (STATE_BITS - RESULT_BITS);
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}
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};
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}
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using p128r64 = detail::XorOshiro<uint64_t, uint64_t, 55, 14, 36>;
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using p128r32 = detail::XorOshiro<uint64_t, uint32_t, 55, 14, 36>;
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using p64r32 = detail::XorOshiro<uint32_t, uint32_t, 27, 7, 20>;
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using p64r16 = detail::XorOshiro<uint32_t, uint16_t, 27, 7, 20>;
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using p32r16 = detail::XorOshiro<uint16_t, uint16_t, 13, 5, 10>;
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using p32r8 = detail::XorOshiro<uint16_t, uint8_t, 13, 5, 10>;
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using p16r8 = detail::XorOshiro<uint8_t, uint8_t, 4, 7, 3>;
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}
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