9bf3b53533
SipHash appears to be the new gold standard for hashing smaller strings for hashtables these days, so let's make use of it.
136 lines
3.9 KiB
C
136 lines
3.9 KiB
C
/*
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SipHash reference C implementation
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Written in 2012 by
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Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
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Daniel J. Bernstein <djb@cr.yp.to>
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To the extent possible under law, the author(s) have dedicated all copyright
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and related and neighboring rights to this software to the public domain
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worldwide. This software is distributed without any warranty.
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You should have received a copy of the CC0 Public Domain Dedication along with
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this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
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(Minimal changes made by Lennart Poettering, to make clean for inclusion in systemd)
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include "siphash24.h"
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typedef uint64_t u64;
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typedef uint32_t u32;
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typedef uint8_t u8;
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#define ROTL(x,b) (u64)( ((x) << (b)) | ( (x) >> (64 - (b))) )
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#define U32TO8_LE(p, v) \
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(p)[0] = (u8)((v) ); (p)[1] = (u8)((v) >> 8); \
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(p)[2] = (u8)((v) >> 16); (p)[3] = (u8)((v) >> 24);
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#define U64TO8_LE(p, v) \
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U32TO8_LE((p), (u32)((v) )); \
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U32TO8_LE((p) + 4, (u32)((v) >> 32));
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#define U8TO64_LE(p) \
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(((u64)((p)[0]) ) | \
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((u64)((p)[1]) << 8) | \
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((u64)((p)[2]) << 16) | \
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((u64)((p)[3]) << 24) | \
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((u64)((p)[4]) << 32) | \
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((u64)((p)[5]) << 40) | \
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((u64)((p)[6]) << 48) | \
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((u64)((p)[7]) << 56))
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#define SIPROUND \
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do { \
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v0 += v1; v1=ROTL(v1,13); v1 ^= v0; v0=ROTL(v0,32); \
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v2 += v3; v3=ROTL(v3,16); v3 ^= v2; \
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v0 += v3; v3=ROTL(v3,21); v3 ^= v0; \
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v2 += v1; v1=ROTL(v1,17); v1 ^= v2; v2=ROTL(v2,32); \
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} while(0)
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/* SipHash-2-4 */
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void siphash24(uint8_t out[8], const void *_in, size_t inlen, const uint8_t k[16])
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{
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/* "somepseudorandomlygeneratedbytes" */
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u64 v0 = 0x736f6d6570736575ULL;
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u64 v1 = 0x646f72616e646f6dULL;
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u64 v2 = 0x6c7967656e657261ULL;
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u64 v3 = 0x7465646279746573ULL;
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u64 b;
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u64 k0 = U8TO64_LE( k );
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u64 k1 = U8TO64_LE( k + 8 );
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u64 m;
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const u8 *in = _in;
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const u8 *end = in + inlen - ( inlen % sizeof( u64 ) );
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const int left = inlen & 7;
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b = ( ( u64 )inlen ) << 56;
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v3 ^= k1;
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v2 ^= k0;
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v1 ^= k1;
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v0 ^= k0;
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for ( ; in != end; in += 8 )
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{
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m = U8TO64_LE( in );
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#ifdef DEBUG
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printf( "(%3d) v0 %08x %08x\n", ( int )inlen, ( u32 )( v0 >> 32 ), ( u32 )v0 );
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printf( "(%3d) v1 %08x %08x\n", ( int )inlen, ( u32 )( v1 >> 32 ), ( u32 )v1 );
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printf( "(%3d) v2 %08x %08x\n", ( int )inlen, ( u32 )( v2 >> 32 ), ( u32 )v2 );
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printf( "(%3d) v3 %08x %08x\n", ( int )inlen, ( u32 )( v3 >> 32 ), ( u32 )v3 );
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printf( "(%3d) compress %08x %08x\n", ( int )inlen, ( u32 )( m >> 32 ), ( u32 )m );
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#endif
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v3 ^= m;
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SIPROUND;
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SIPROUND;
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v0 ^= m;
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}
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switch( left )
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{
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case 7: b |= ( ( u64 )in[ 6] ) << 48;
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case 6: b |= ( ( u64 )in[ 5] ) << 40;
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case 5: b |= ( ( u64 )in[ 4] ) << 32;
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case 4: b |= ( ( u64 )in[ 3] ) << 24;
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case 3: b |= ( ( u64 )in[ 2] ) << 16;
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case 2: b |= ( ( u64 )in[ 1] ) << 8;
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case 1: b |= ( ( u64 )in[ 0] ); break;
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case 0: break;
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}
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#ifdef DEBUG
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printf( "(%3d) v0 %08x %08x\n", ( int )inlen, ( u32 )( v0 >> 32 ), ( u32 )v0 );
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printf( "(%3d) v1 %08x %08x\n", ( int )inlen, ( u32 )( v1 >> 32 ), ( u32 )v1 );
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printf( "(%3d) v2 %08x %08x\n", ( int )inlen, ( u32 )( v2 >> 32 ), ( u32 )v2 );
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printf( "(%3d) v3 %08x %08x\n", ( int )inlen, ( u32 )( v3 >> 32 ), ( u32 )v3 );
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printf( "(%3d) padding %08x %08x\n", ( int )inlen, ( u32 )( b >> 32 ), ( u32 )b );
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#endif
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v3 ^= b;
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SIPROUND;
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SIPROUND;
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v0 ^= b;
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#ifdef DEBUG
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printf( "(%3d) v0 %08x %08x\n", ( int )inlen, ( u32 )( v0 >> 32 ), ( u32 )v0 );
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printf( "(%3d) v1 %08x %08x\n", ( int )inlen, ( u32 )( v1 >> 32 ), ( u32 )v1 );
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printf( "(%3d) v2 %08x %08x\n", ( int )inlen, ( u32 )( v2 >> 32 ), ( u32 )v2 );
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printf( "(%3d) v3 %08x %08x\n", ( int )inlen, ( u32 )( v3 >> 32 ), ( u32 )v3 );
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#endif
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v2 ^= 0xff;
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SIPROUND;
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SIPROUND;
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SIPROUND;
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SIPROUND;
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b = v0 ^ v1 ^ v2 ^ v3;
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U64TO8_LE( out, b );
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}
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