53 lines
1.7 KiB
GLSL
53 lines
1.7 KiB
GLSL
/*
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* Copyright (c) 2019-2021, NVIDIA CORPORATION. All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* SPDX-FileCopyrightText: Copyright (c) 2019-2021 NVIDIA CORPORATION
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* SPDX-License-Identifier: Apache-2.0
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*/
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// Generate a random unsigned int from two unsigned int values, using 16 pairs
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// of rounds of the Tiny Encryption Algorithm. See Zafar, Olano, and Curtis,
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// "GPU Random Numbers via the Tiny Encryption Algorithm"
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uint tea(uint val0, uint val1)
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{
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uint v0 = val0;
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uint v1 = val1;
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uint s0 = 0;
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for(uint n = 0; n < 16; n++)
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{
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s0 += 0x9e3779b9;
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v0 += ((v1 << 4) + 0xa341316c) ^ (v1 + s0) ^ ((v1 >> 5) + 0xc8013ea4);
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v1 += ((v0 << 4) + 0xad90777d) ^ (v0 + s0) ^ ((v0 >> 5) + 0x7e95761e);
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}
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return v0;
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}
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// Generate a random unsigned int in [0, 2^24) given the previous RNG state
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// using the Numerical Recipes linear congruential generator
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uint lcg(inout uint prev)
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{
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uint LCG_A = 1664525u;
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uint LCG_C = 1013904223u;
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prev = (LCG_A * prev + LCG_C);
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return prev & 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 prev)
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{
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return (float(lcg(prev)) / float(0x01000000));
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}
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