136 lines
2.9 KiB
C++
136 lines
2.9 KiB
C++
// hash.cpp
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// Author: Josh Holtrop
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// Date: 08/28/05
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// Modified: 08/28/05
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// Implements a basic hash table (u32_t -> void*)
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#define __HOS_CPP__
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#include "hos_defines.h"
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#include "hash.h"
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#include "lang/vector.h"
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extern "C"{
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#include "display/kout.h"
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#include "mm/vmm.h"
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}
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/* Hash Primes come from
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* http://planetmath.org/encyclopedia/GoodHashTablePrimes.html
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*/
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const u32_t hash_primes[] =
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{53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593, 49157, 98317,
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196613, 393241, 786433, 1572869, 3145739, 6291469, 12582917, 25165843,
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50331653, 100663319, 201326611, 402653189, 805306457, 1610612741};
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hash::hash()
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{
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mySizeIndex = 0;
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mySize = 0;
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myTable = new (vector<hash_entry_t *> *)[hash_primes[mySizeIndex]];
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for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
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myTable[i] = NULL;
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}
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int hash::add(u32_t key, void *val)
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{
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kprintf("$1$");
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u32_t hashed = hash_key(key);
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vector<hash_entry_t *> *vec = myTable[hashed];
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kprintf("$2$");
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if (!vec)
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myTable[hashed] = vec = new vector<hash_entry_t *>;
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for (u32_t i = 0; i < vec->size(); i++)
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if ( (*vec)[i]->key == key )
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return -1; // key exists already
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kprintf("$3$");
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hash_entry_t *he = (hash_entry_t *) New(hash_entry_t);
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kprintf("(");
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for (u32_t i = 0; i < vec->size(); i++)
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kprintf("%d,", (*vec)[i]->key);
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kprintf(")");
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he->key = key;
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he->data = val;
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vec->add(he);
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mySize++;
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kprintf("*%d*\t", mySize);
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if ( mySize > (hash_primes[mySizeIndex] << 1) ) // re-hash
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{
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kprintf("*1*");
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vector<hash_entry_t *> **oldTable = myTable;
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mySizeIndex++;
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myTable = new (vector<hash_entry_t *> *)[hash_primes[mySizeIndex]];
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for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
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myTable[i] = NULL;
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mySize = 0;
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kprintf("*2*");
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for (u32_t i = 0; i < hash_primes[mySizeIndex - 1]; i++)
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{
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if (oldTable[i])
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{
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for (u32_t j = 0; j < oldTable[i]->size(); j++)
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{
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add( (*(oldTable[i]))[j]->key,
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(*(oldTable[i]))[j]->data );
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kfree( (*(oldTable[i]))[j] );
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}
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delete oldTable[i];
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}
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}
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kprintf("*3*");
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delete oldTable;
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}
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return 0;
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}
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void *hash::get(u32_t key)
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{
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u32_t hashed = hash_key(key);
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vector<hash_entry_t *> *vec = myTable[hashed];
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if (!vec)
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return NULL;
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for (u32_t i = 0; i < vec->size(); i++)
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if ( (*vec)[i]->key == key )
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return (*vec)[i]->data;
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return NULL;
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}
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int hash::remove(u32_t key)
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{
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u32_t hashed = hash_key(key);
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vector<hash_entry_t *> *vec = myTable[hashed];
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if (!vec)
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return -1;
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for (u32_t i = 0; i < vec->size(); i++)
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if ( (*vec)[i]->key == key )
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{
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kfree( (*vec)[i] );
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vec->remove(i); // remove key
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mySize--;
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return 0;
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}
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return -1;
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}
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int hash::exists(u32_t key)
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{
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u32_t hashed = hash_key(key);
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vector<hash_entry_t *> *vec = myTable[hashed];
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if (!vec)
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return 0;
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for (u32_t i = 0; i < vec->size(); i++)
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if ( (*vec)[i]->key == key )
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return 1; // key exists
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return 0;
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}
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u32_t hash::hash_key(u32_t key)
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{
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return key % hash_primes[mySizeIndex];
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}
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u32_t hash::size()
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{
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return mySize;
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}
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