gcache.h

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// $Id: gcache.h 754 2006-04-01 15:29:59Z alex $
//
// GCache.h
//
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 */

CONST UINT32 FREE = 0xffffffff ;

struct CacheBlock {
    CacheBlock  *Prev ;
    CacheBlock  *Next ;
    union {
        struct {
            CacheBlock  *PrevFree ;
            CacheBlock  *NextFree ;
            UINT32      State ;
        } ;
        struct {
            CacheBlock  *PrevUsed ;
            CacheBlock  *NextUsed ;
            CacheBlock  *Link ;
            UINT32      Handle ;
            INT32       Object[1] ;
        } ;
    } ;
} ;

// For some reason the size of Object[] is not included in the latter calc, presumably because
// it's not really of size[1] - AMB
const size_t FreeCacheBlockSize = 4 * sizeof(CacheBlock *) + sizeof (UINT32) ;
const size_t UsedCacheBlockSize = 5 * sizeof(CacheBlock *) + sizeof (UINT32) ;


/************************************************************************************************
// Gavin's original defaults
//GCache( size_t Size = 0x40000, UINT32 Log2MaxEntries = 12 ) ;

// The size of the cache is 128k, average character size = 1k, We allow a maximum of 1K entries
//GCache( size_t Size = 0x20000, UINT32 Log2MaxEntries = 10 ) ;


    Size specifies the byte size of the cache. Log2MaxEntries specifes the number of entries in
    the hash table. Note that the cache will still work even if there are more characters than
    the size of the hash table.

BOOL Verify() ;
    This will return TRUE if the cache is in use. Use after construction to ensure that
    construction succeeded.

BOOL FindPath( UINT32 Handle, INT32* &Points, BYTE* &Types, UINT32 &Length ) ;

    Searches for the given handle. If found it returns TRUE and returns the associated path in
    Points, Types and Length, else it returns FALSE.

void AddPath( UINT32 Handle, INT32*  Points, BYTE*  Types, UINT32  Length ) ;

    Stores the given path in the cache using the specified handle.

char* FindString( UINT32 Handle ) ;

    Searches for the given handle. If found it returns the string associated with the handle,
    else it returns FALSE.

void  AddString( UINT32 Handle, char* String ) ;

    Stores the given string in the cache using the specified handle.

************************************************************************************************/

class CamCache
{
#ifdef _DEBUG
    friend ostream& operator << ( ostream& os, CamCache& Cache ) ;
#endif

public:
    CamCache( size_t Size = 0x40000, UINT32 Log2MaxEntries = 12 ) ;
    ~CamCache() ;
    BOOL Verify() ;

    BOOL FindPath( UINT32 Handle, INT32* &Points, BYTE* &Types, UINT32 &Length ) ;
    void  AddPath( UINT32 Handle, INT32*  Points, BYTE*  Types, UINT32  Length ) ;

    char* FindString( UINT32 Handle ) ;
    void   AddString( UINT32 Handle, char* String ) ;

private:
    size_t      HashTableSize ;
    UINT32      HashTableMask ;
    CacheBlock  **HashTable ;

    CacheBlock  *CacheStart ;
    CacheBlock  *CacheEnd ;

    CacheBlock  *LeastUsed ;
    CacheBlock  *MostUsed ;

    void* FindEntry( UINT32 Handle ) ;
    void*  AddEntry( UINT32 Handle, size_t ObjectSize ) ;

    inline size_t BlockSize( CacheBlock* Block )
    {
        return (size_t)((BYTE*)Block->Next-(BYTE*)Block) ;
    } ;
} ;

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