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45 lines
1 KiB
C
45 lines
1 KiB
C
#ifndef ADDRESS_HASH_H
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#define ADDRESS_HASH_H
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#include <stdint.h>
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static uintptr_t hash_address(uintptr_t x) {
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if (sizeof (x) < 8) {
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// Chris Wellon's lowbias32, from https://nullprogram.com/blog/2018/07/31/.
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x ^= x >> 16;
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x *= 0x7feb352dU;
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x ^= x >> 15;
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x *= 0x846ca68bU;
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x ^= x >> 16;
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return x;
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} else {
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// Sebastiano Vigna's splitmix64 integer mixer, from
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// https://prng.di.unimi.it/splitmix64.c.
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x ^= x >> 30;
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x *= 0xbf58476d1ce4e5b9U;
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x ^= x >> 27;
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x *= 0x94d049bb133111ebU;
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x ^= x >> 31;
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return x;
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}
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}
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// Inverse of hash_address from https://nullprogram.com/blog/2018/07/31/.
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static uintptr_t unhash_address(uintptr_t x) {
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if (sizeof (x) < 8) {
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x ^= x >> 16;
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x *= 0x43021123U;
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x ^= x >> 15 ^ x >> 30;
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x *= 0x1d69e2a5U;
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x ^= x >> 16;
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return x;
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} else {
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x ^= x >> 31 ^ x >> 62;
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x *= 0x319642b2d24d8ec3U;
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x ^= x >> 27 ^ x >> 54;
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x *= 0x96de1b173f119089U;
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x ^= x >> 30 ^ x >> 60;
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return x;
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}
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}
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#endif // ADDRESS_HASH_H
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