39 lines
2.4 KiB
C
39 lines
2.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/morton.h"
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/**
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* Interleaves bits.
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* @see https://en.wikipedia.org/wiki/Z-order_curve
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* @see unmorton()
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*/
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unsigned long(morton)(unsigned long y, unsigned long x) {
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x = (x | x << 020) & 0x0000FFFF0000FFFF;
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x = (x | x << 010) & 0x00FF00FF00FF00FF;
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x = (x | x << 004) & 0x0F0F0F0F0F0F0F0F;
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x = (x | x << 002) & 0x3333333333333333;
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x = (x | x << 001) & 0x5555555555555555;
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y = (y | y << 020) & 0x0000FFFF0000FFFF;
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y = (y | y << 010) & 0x00FF00FF00FF00FF;
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y = (y | y << 004) & 0x0F0F0F0F0F0F0F0F;
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y = (y | y << 002) & 0x3333333333333333;
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y = (y | y << 001) & 0x5555555555555555;
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return x | y << 1;
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}
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