4coder/custom/4coder_hash_functions.cpp

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/*
* Mr. 4th Dimention - Allen Webster
*
* 26.08.2018
*
* Generic hash functions
*
*/
// TOP
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#if !defined(FCODER_HASH_FUNCTIONS_CPP)
#define FCODER_HASH_FUNCTIONS_CPP
static u64
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table_hash_u8(u8 *v, umem size){
u64 hash = 0;
for (u8 *p = v, *e = v + size; p < e; p += 1){
u8 k = *p;
k *= 81;
k = ((u8)(k << 4)) | ((u8)(k >> 4));
hash ^= k;
hash *= 11;
hash += 237;
}
return(hash);
}
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static u64
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table_hash_u16(u16 *v, umem size){
u64 hash = 0;
for (u16 *p = v, *e = v + size; p < e; p += 1){
u16 k = *p;
k *= 11601;
k = ((u16)(k << 8)) | ((u16)(k >> 8));
hash ^= k;
hash *= 11;
hash += 12525;
}
return(hash);
}
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static u64
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table_hash_u32(u32 *v, umem size){
u64 hash = 0;
for (u32 *p = v, *e = v + size; p < e; p += 1){
u32 k = *p;
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k *= 3432918353U;
k = ((u32)(k << 16)) | ((u32)(k >> 16));
hash ^= k;
hash *= 11;
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hash += 2041000173U;
}
return(hash);
}
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static u64
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table_hash_u64(u64 *v, umem size){
u64 hash = 0;
for (u64 *p = v, *e = v + size; p < e; p += 1){
u64 k = *p;
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k *= 14744272059406101841ULL;
k = ((u64)(k << 32)) | ((u64)(k >> 32));
hash ^= k;
hash *= 11;
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hash += 8766028991911375085ULL;
}
return(hash);
}
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static u64
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table_hash(void *v, i32 it_size, umem size){
u64 hash = 0;
switch (it_size){
case 1:
{
hash = table_hash_u8((u8*)v, size);
}break;
case 2:
{
hash = table_hash_u16((u16*)v, size);
}break;
case 4:
{
hash = table_hash_u32((u32*)v, size);
}break;
case 8:
{
hash = table_hash_u64((u64*)v, size);
}break;
default:
{
hash = table_hash_u8((u8*)v, it_size*size);
}break;
}
return(hash);
}
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#endif
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// BOTTOM