37 lines
1.1 KiB
Text
37 lines
1.1 KiB
Text
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/* Copyright (c) 2023, Sascha Willems
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*
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* SPDX-License-Identifier: MIT
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*
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*/
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// Tiny Encryption Algorithm
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// By Fahad Zafar, Marc Olano and Aaron Curtis, see https://www.highperformancegraphics.org/previous/www_2010/media/GPUAlgorithms/HPG2010_GPUAlgorithms_Zafar.pdf
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uint tea(uint val0, uint val1)
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{
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uint sum = 0;
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uint v0 = val0;
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uint v1 = val1;
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for (uint n = 0; n < 16; n++)
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{
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sum += 0x9E3779B9;
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v0 += ((v1 << 4) + 0xA341316C) ^ (v1 + sum) ^ ((v1 >> 5) + 0xC8013EA4);
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v1 += ((v0 << 4) + 0xAD90777D) ^ (v0 + sum) ^ ((v0 >> 5) + 0x7E95761E);
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}
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return v0;
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}
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// Linear congruential generator based on the previous RNG state
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// See https://en.wikipedia.org/wiki/Linear_congruential_generator
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uint lcg(inout uint previous)
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{
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const uint multiplier = 1664525u;
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const uint increment = 1013904223u;
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previous = (multiplier * previous + increment);
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return previous & 0x00FFFFFF;
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}
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// Generate a random float in [0, 1) given the previous RNG state
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float rnd(inout uint previous)
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{
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return (float(lcg(previous)) / float(0x01000000));
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}
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