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/* SPDX-License-Identifier: Apache-2.0
* Copyright 2011-2022 Blender Foundation */
#pragma once
#include "util/types.h"
CCL_NAMESPACE_BEGIN
/*
* Performs base-2 Owen scrambling on a reversed-bit unsigned integer.
*
* This is equivalent to the Laine-Karras permutation, but much higher
* quality. See https://psychopath.io/post/2021_01_30_building_a_better_lk_hash
*/
ccl_device_inline uint reversed_bit_owen(uint n, uint seed)
{
n ^= n * 0x3d20adea;
n += seed;
n *= (seed >> 16) | 1;
n ^= n * 0x05526c56;
n ^= n * 0x53a22864;
return n;
}
/*
* Performs base-2 Owen scrambling on an unsigned integer.
*/
ccl_device_inline uint nested_uniform_scramble(uint i, uint seed)
{
return reverse_integer_bits(reversed_bit_owen(reverse_integer_bits(i), seed));
}
CCL_NAMESPACE_END
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