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/*****************************************************************************/
/* Map.cpp Copyright (c) Ladislav Zezula 2014 */
/*---------------------------------------------------------------------------*/
/* Implementation of map for CascLib */
/*---------------------------------------------------------------------------*/
/* Date Ver Who Comment */
/* -------- ---- --- ------- */
/* 10.06.14 1.00 Lad The first version of Map.cpp */
/*****************************************************************************/
#define __CASCLIB_SELF__
#include "../CascLib.h"
#include "../CascCommon.h"
//-----------------------------------------------------------------------------
// Local functions
static DWORD CalcHashIndex(PCASC_MAP pMap, void * pvIdentifier)
{
DWORD dwHash = 0x7EEE7EEE;
// Is it a string table?
if(pMap->KeyLength == KEY_LENGTH_STRING)
{
char * szString = (char *)pvIdentifier;
for(size_t i = 0; szString[i] != 0; i++)
dwHash = (dwHash >> 24) ^ (dwHash << 5) ^ dwHash ^ szString[i];
}
else
{
LPBYTE pbHash = (LPBYTE)pvIdentifier;
// Construct the hash from the first 4 digits
for(size_t i = 0; i < pMap->KeyLength; i++)
dwHash = (dwHash >> 24) ^ (dwHash << 5) ^ dwHash ^ pbHash[i];
}
// Return the hash limited by the table size
return (dwHash % pMap->TableSize);
}
static bool CompareIdentifier(PCASC_MAP pMap, void * pvTableEntry, void * pvIdentifier)
{
// Is it a string table?
if(pMap->KeyLength == KEY_LENGTH_STRING)
{
char * szTableEntry = (char *)pvTableEntry;
char * szIdentifier = (char *)pvIdentifier;
return (strcmp(szTableEntry, szIdentifier) == 0);
}
else
{
return (memcmp(pvTableEntry, pvIdentifier, pMap->KeyLength) == 0);
}
}
//-----------------------------------------------------------------------------
// Public functions
PCASC_MAP Map_Create(DWORD dwMaxItems, DWORD dwKeyLength, DWORD dwMemberOffset)
{
PCASC_MAP pMap;
size_t cbToAllocate;
size_t dwTableSize;
// Calculate the size of the table
dwTableSize = (dwMaxItems * 3 / 2) | 0x01;
// Allocate new map for the objects
cbToAllocate = sizeof(CASC_MAP) + (dwTableSize * sizeof(void *));
pMap = (PCASC_MAP)CASC_ALLOC(LPBYTE, cbToAllocate);
if(pMap != NULL)
{
memset(pMap, 0, cbToAllocate);
pMap->KeyLength = dwKeyLength;
pMap->TableSize = dwTableSize;
pMap->MemberOffset = dwMemberOffset;
}
// Return the allocated map
return pMap;
}
size_t Map_EnumObjects(PCASC_MAP pMap, void **ppvArray)
{
size_t nIndex = 0;
// Verify pointer to the map
if(pMap != NULL && ppvArray != NULL)
{
// Enumerate all items in main table
for(size_t i = 0; i < pMap->TableSize; i++)
{
// Is that cell valid?
if(pMap->HashTable[i] != NULL)
{
ppvArray[nIndex++] = pMap->HashTable[i];
}
}
}
return pMap->ItemCount;
}
void * Map_FindObject(PCASC_MAP pMap, void * pvIdentifier)
{
void * pvTableEntry;
DWORD dwHashIndex;
// Verify pointer to the map
if(pMap != NULL)
{
// Construct the main index
dwHashIndex = CalcHashIndex(pMap, pvIdentifier);
while(pMap->HashTable[dwHashIndex] != NULL)
{
// Get the pointer at that position
pvTableEntry = pMap->HashTable[dwHashIndex];
// Compare the hash
if(CompareIdentifier(pMap, pvTableEntry, pvIdentifier))
return ((LPBYTE)pvTableEntry - pMap->MemberOffset);
// Move to the next entry
dwHashIndex = (dwHashIndex + 1) % pMap->TableSize;
}
}
// Not found, sorry
return NULL;
}
bool Map_InsertObject(PCASC_MAP pMap, void * pvIdentifier)
{
void * pvTableEntry;
DWORD dwHashIndex;
// Verify pointer to the map
if(pMap != NULL)
{
// Limit check
if((pMap->ItemCount + 1) >= pMap->TableSize)
return false;
// Construct the hash index
dwHashIndex = CalcHashIndex(pMap, pvIdentifier);
while(pMap->HashTable[dwHashIndex] != NULL)
{
// Get the pointer at that position
pvTableEntry = pMap->HashTable[dwHashIndex];
// Check if hash being inserted conflicts with an existing hash
if(CompareIdentifier(pMap, pvTableEntry, pvIdentifier))
return false;
// Move to the next entry
dwHashIndex = (dwHashIndex + 1) % pMap->TableSize;
}
// Insert at that position
pMap->HashTable[dwHashIndex] = pvIdentifier;
pMap->ItemCount++;
return true;
}
// Failed
return false;
}
void Map_Free(PCASC_MAP pMap)
{
if(pMap != NULL)
{
CASC_FREE(pMap);
}
}
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