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hl2sdk/tier1/generichash.cpp
2017-05-30 15:22:52 -05:00

304 lines
9.0 KiB
C++

//======= Copyright © 2005, , Valve Corporation, All rights reserved. =========
//
// Purpose: Variant Pearson Hash general purpose hashing algorithm described
// by Cargill in C++ Report 1994. Generates a 16-bit result.
//
//=============================================================================
#include <stdlib.h>
#include "tier0/basetypes.h"
#include "tier0/platform.h"
#include "generichash.h"
#include <ctype.h>
//-----------------------------------------------------------------------------
//
// Table of randomly shuffled values from 0-255 generated by:
//
//-----------------------------------------------------------------------------
/*
void MakeRandomValues()
{
int i, j, r;
unsigned t;
srand( 0xdeadbeef );
for ( i = 0; i < 256; i++ )
{
g_nRandomValues[i] = (unsigned )i;
}
for (j = 0; j < 8; j++)
{
for (i = 0; i < 256; i++)
{
r = rand() & 0xff;
t = g_nRandomValues[i];
g_nRandomValues[i] = g_nRandomValues[r];
g_nRandomValues[r] = t;
}
}
printf("static unsigned g_nRandomValues[256] =\n{\n");
for (i = 0; i < 256; i += 16)
{
printf("\t");
for (j = 0; j < 16; j++)
printf(" %3d,", g_nRandomValues[i+j]);
printf("\n");
}
printf("};\n");
}
*/
static unsigned g_nRandomValues[256] =
{
238, 164, 191, 168, 115, 16, 142, 11, 213, 214, 57, 151, 248, 252, 26, 198,
13, 105, 102, 25, 43, 42, 227, 107, 210, 251, 86, 66, 83, 193, 126, 108,
131, 3, 64, 186, 192, 81, 37, 158, 39, 244, 14, 254, 75, 30, 2, 88,
172, 176, 255, 69, 0, 45, 116, 139, 23, 65, 183, 148, 33, 46, 203, 20,
143, 205, 60, 197, 118, 9, 171, 51, 233, 135, 220, 49, 71, 184, 82, 109,
36, 161, 169, 150, 63, 96, 173, 125, 113, 67, 224, 78, 232, 215, 35, 219,
79, 181, 41, 229, 149, 153, 111, 217, 21, 72, 120, 163, 133, 40, 122, 140,
208, 231, 211, 200, 160, 182, 104, 110, 178, 237, 15, 101, 27, 50, 24, 189,
177, 130, 187, 92, 253, 136, 100, 212, 19, 174, 70, 22, 170, 206, 162, 74,
247, 5, 47, 32, 179, 117, 132, 195, 124, 123, 245, 128, 236, 223, 12, 84,
54, 218, 146, 228, 157, 94, 106, 31, 17, 29, 194, 34, 56, 134, 239, 246,
241, 216, 127, 98, 7, 204, 154, 152, 209, 188, 48, 61, 87, 97, 225, 85,
90, 167, 155, 112, 145, 114, 141, 93, 250, 4, 201, 156, 38, 89, 226, 196,
1, 235, 44, 180, 159, 121, 119, 166, 190, 144, 10, 91, 76, 230, 221, 80,
207, 55, 58, 53, 175, 8, 6, 52, 68, 242, 18, 222, 103, 249, 147, 129,
138, 243, 28, 185, 62, 59, 240, 202, 234, 99, 77, 73, 199, 137, 95, 165,
};
//-----------------------------------------------------------------------------
// String
//-----------------------------------------------------------------------------
unsigned FASTCALL HashString( const char *pszKey )
{
const uint8 *k = (const uint8 *)pszKey;
unsigned even = 0,
odd = 0,
n;
while ((n = *k++) != 0)
{
even = g_nRandomValues[odd ^ n];
if ((n = *k++) != 0)
odd = g_nRandomValues[even ^ n];
else
break;
}
return (even << 8) | odd ;
}
//-----------------------------------------------------------------------------
// Case-insensitive string
//-----------------------------------------------------------------------------
unsigned FASTCALL HashStringCaseless( const char *pszKey )
{
const uint8 *k = (const uint8 *) pszKey;
unsigned even = 0,
odd = 0,
n;
while ((n = toupper(*k++)) != 0)
{
even = g_nRandomValues[odd ^ n];
if ((n = toupper(*k++)) != 0)
odd = g_nRandomValues[even ^ n];
else
break;
}
return (even << 8) | odd;
}
//-----------------------------------------------------------------------------
// 32 bit conventional case-insensitive string
//-----------------------------------------------------------------------------
unsigned FASTCALL HashStringCaselessConventional( const char *pszKey )
{
unsigned hash = 0xAAAAAAAA; // Alternating 1's and 0's to maximize the effect of the later multiply and add
for( ; *pszKey ; pszKey++ )
{
hash = ( ( hash << 5 ) + hash ) + (uint8)tolower(*pszKey);
}
return hash;
}
//-----------------------------------------------------------------------------
// int hash
//-----------------------------------------------------------------------------
unsigned FASTCALL HashInt( const int n )
{
unsigned even, odd;
even = g_nRandomValues[n & 0xff];
odd = g_nRandomValues[((n >> 8) & 0xff)];
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
return (even << 8) | odd;
}
//-----------------------------------------------------------------------------
// 4-byte hash
//-----------------------------------------------------------------------------
unsigned FASTCALL Hash4( const void *pKey )
{
const uint32 * p = (const uint32 *) pKey;
unsigned even,
odd,
n;
n = *p;
even = g_nRandomValues[n & 0xff];
odd = g_nRandomValues[((n >> 8) & 0xff)];
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
return (even << 8) | odd;
}
//-----------------------------------------------------------------------------
// 8-byte hash
//-----------------------------------------------------------------------------
unsigned FASTCALL Hash8( const void *pKey )
{
const uint32 * p = (const uint32 *) pKey;
unsigned even,
odd,
n;
n = *p;
even = g_nRandomValues[n & 0xff];
odd = g_nRandomValues[((n >> 8) & 0xff)];
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
n = *(p+1);
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
return (even << 8) | odd;
}
//-----------------------------------------------------------------------------
// 12-byte hash
//-----------------------------------------------------------------------------
unsigned FASTCALL Hash12( const void *pKey )
{
const uint32 * p = (const uint32 *) pKey;
unsigned even,
odd,
n;
n = *p;
even = g_nRandomValues[n & 0xff];
odd = g_nRandomValues[((n >> 8) & 0xff)];
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
n = *(p+1);
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
n = *(p+2);
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
return (even << 8) | odd;
}
//-----------------------------------------------------------------------------
// 16-byte hash
//-----------------------------------------------------------------------------
unsigned FASTCALL Hash16( const void *pKey )
{
const uint32 * p = (const uint32 *) pKey;
unsigned even,
odd,
n;
n = *p;
even = g_nRandomValues[n & 0xff];
odd = g_nRandomValues[((n >> 8) & 0xff)];
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
n = *(p+1);
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
n = *(p+2);
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
n = *(p+3);
even = g_nRandomValues[odd ^ (n >> 24)];
odd = g_nRandomValues[even ^ ((n >> 16) & 0xff)];
even = g_nRandomValues[odd ^ ((n >> 8) & 0xff)];
odd = g_nRandomValues[even ^ (n & 0xff)];
return (even << 8) | odd;
}
//-----------------------------------------------------------------------------
// Arbitrary fixed length hash
//-----------------------------------------------------------------------------
unsigned FASTCALL HashBlock( const void *pKey, unsigned size )
{
const uint8 * k = (const uint8 *) pKey;
unsigned even = 0,
odd = 0,
n;
while (size)
{
--size;
n = *k++;
even = g_nRandomValues[odd ^ n];
if (size)
{
--size;
n = *k++;
odd = g_nRandomValues[even ^ n];
}
else
break;
}
return (even << 8) | odd;
}