353 lines
14 KiB
C
353 lines
14 KiB
C
/***************************************************************************/
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/* */
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/* ftcmanag.h */
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/* */
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/* FreeType Cache Manager (specification). */
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/* */
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/* Copyright 2000 by */
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */
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/* */
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/* This file is part of the FreeType project, and may only be used, */
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/* modified, and distributed under the terms of the FreeType project */
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
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/* this file you indicate that you have read the license and */
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/* understand and accept it fully. */
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/* */
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/***************************************************************************/
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/*************************************************************************/
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/* */
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/* A cache manager is in charge of the following: */
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/* */
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/* - Maintain a mapping between generic FTC_FaceIDs and live FT_Face */
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/* objects. The mapping itself is performed through a user-provided */
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/* callback. However, the manager maintains a small cache of FT_Face */
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/* & FT_Size objects in order to speed things considerably. */
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/* */
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/* - Manage one or more cache objects. Each cache is in charge of */
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/* holding a varying number of `cache nodes'. Each cache node */
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/* represents a minimal amount of individually-accessible cached */
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/* data. For example, a cache node can be an FT_Glyph image */
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/* containing a vector outline, or some glyph metrics, or anything */
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/* else. */
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/* */
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/* Each cache node has a certain size in bytes that is added to the */
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/* total amount of `cache memory' within the manager. */
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/* */
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/* All cache nodes are located in a global LRU list, where the oldest */
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/* node is at the tail of the list. */
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/* */
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/* Each node belongs to a single cache, and includes a reference */
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/* count to avoid destroying it (due to caching). */
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/* */
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/********* *********/
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/********* WARNING, THIS IS ALPHA CODE, THIS API *********/
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/********* IS DUE TO CHANGE UNTIL STRICTLY NOTIFIED BY THE *********/
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/********* FREETYPE DEVELOPMENT TEAM *********/
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/********* *********/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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#ifndef FTCMANAG_H
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#define FTCMANAG_H
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#include <freetype/ftcache.h>
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#include <freetype/cache/ftlru.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define FTC_MAX_FACES_DEFAULT 2
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#define FTC_MAX_SIZES_DEFAULT 4
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#define FTC_MAX_BYTES_DEFAULT 200000 /* 200kByte by default! */
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/* maximum number of caches registered in a single manager */
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#define FTC_MAX_CACHES 16
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/****************************************************************
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*
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* <Struct> FTC_ManagerRec
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*
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* <Description>
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* the cache manager structure. Each cache manager is in
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* charge of performing two tasks:
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*
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* <Fields>
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* library :: handle to FreeType library instance
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* faces_lru :: lru list of FT_Face objects in cache
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* sizes_lru :: lru list of FT_Size objects in cache
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*
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* max_bytes :: maximum number of bytes to be allocated
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* in the cache. this is only related to
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* the byte size of the nodes cached by
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* the manager.
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*
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* num_bytes :: current number of bytes allocated in
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* the cache. only related to the byte size
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* of cached nodes.
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*
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* num_nodes :: current number of nodes in the manager
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*
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* global_lru :: the global lru list of all cache nodes
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*
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* caches :: a table of installed/registered cache
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* objects
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*
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* request_data :: user-provided data passed to the requester
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* request_face :: user-provided function used to implement
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* a mapping between abstract FTC_FaceIDs
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* and real FT_Face objects..
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*/
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typedef struct FTC_ManagerRec_
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{
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FT_Library library;
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FT_Lru faces_lru;
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FT_Lru sizes_lru;
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FT_ULong max_bytes;
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FT_ULong num_bytes;
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FT_UInt num_nodes;
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FT_ListRec global_lru;
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FTC_Cache caches[FTC_MAX_CACHES];
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FT_Pointer request_data;
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FTC_Face_Requester request_face;
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} FTC_ManagerRec;
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/**********************************************************************
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*
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* <Function> FTC_Manager_Compress
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*
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* <Description>
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* this function is used to check the state of the cache manager
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* if its "num_bytes" field is greater than its "max_bytes"
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* field, this function will flush as many old cache nodes as
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* possible (ignoring cache nodes with a non-zero reference
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* count).
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*
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* <input>
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* manager :: handle to cache manager
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*
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* <note>
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* client applications should not call this function directly.
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* it is normally invoked by specific cache implementations.
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*
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* the reason this function is exported is to allow client-
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* specific cache classes..
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*
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*/
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FT_EXPORT_DEF( void ) FTC_Manager_Compress( FTC_Manager manager );
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** CACHE NODE DEFINITIONS *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/* */
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/* Each cache controls one or more cache nodes. Each node is part of */
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/* the global_lru list of the manager. Its `data' field however is used */
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/* as a reference count for now. */
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/* */
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/* A node can be anything, depending on the type of information held by */
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/* the cache. It can be an individual glyph image, a set of bitmaps */
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/* glyphs for a given size, some metrics, etc. */
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/* */
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typedef FT_ListNodeRec FTC_CacheNodeRec;
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typedef FTC_CacheNodeRec* FTC_CacheNode;
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/* the fields `cachenode.data' is typecasted to this type */
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typedef struct FTC_CacheNode_Data_
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{
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FT_UShort cache_index;
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FT_Short ref_count;
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} FTC_CacheNode_Data;
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/* return a pointer to the FTC_CacheNode_Data contained in a */
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/* CacheNode's `data' field */
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#define FTC_CACHENODE_TO_DATA_P( n ) \
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( (FTC_CacheNode_Data*)&(n)->data )
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#define FTC_LIST_TO_CACHENODE( n ) ( (FTC_CacheNode)(n) )
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/**********************************************************************
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*
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* <FuncType> FTC_CacheNode_SizeFunc
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*
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* <Description>
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* a function used to compute the total size in bytes of a given
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* cache node. It is used by the cache manager to compute the
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* number of old nodes to flush when the cache is full..
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*
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* <Input>
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* node :: handle to target cache node
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* cache_data :: a generic pointer passed to the destructor.
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*/
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typedef FT_ULong (*FTC_CacheNode_SizeFunc)( FTC_CacheNode node,
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FT_Pointer cache_data );
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/**********************************************************************
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*
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* <FuncType> FTC_CacheNode_DestroyFunc
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*
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* <Description>
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* a function used to destroy a given cache node. It is called
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* by the manager when the cache is full and old nodes need to
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* be flushed out..
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*
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* <Input>
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* node :: handle to target cache node
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* cache_data :: a generic pointer passed to the destructor.
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*/
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typedef void (*FTC_CacheNode_DestroyFunc)( FTC_CacheNode node,
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FT_Pointer cache_data );
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/**********************************************************************
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*
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* <Struct> FTC_CacheNode_Class
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*
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* <Description>
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* a very simple structure used to describe a cache node's class
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* to the cache manager
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*
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* <Fields>
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* size_node :: a function used to size the node
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* destroy_node :: a function used to destroy the node
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*
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* <Note>
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* the cache node class doesn't include a "new_node" function
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* because the cache manager never allocates cache node directly,
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* it delegates this task to its cache objects..
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*
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*/
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typedef struct FTC_CacheNode_Class_
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{
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FTC_CacheNode_SizeFunc size_node;
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FTC_CacheNode_DestroyFunc destroy_node;
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} FTC_CacheNode_Class;
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** CACHE DEFINITIONS *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/**********************************************************************
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*
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* <FuncType> FTC_Cache_InitFunc
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*
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* <Description>
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* a function used to initialize a given cache object
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*
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* <Input>
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* cache :: handle to new cache
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*/
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typedef FT_Error (*FTC_Cache_InitFunc)( FTC_Cache cache );
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/**********************************************************************
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*
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* <FuncType> FTC_Cache_DoneFunc
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*
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* <Description>
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* a function used to finalize a given cache object
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*
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* <Input>
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* cache :: handle to target cache
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*/
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typedef void (*FTC_Cache_DoneFunc)( FTC_Cache cache );
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/**********************************************************************
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*
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* <Struct> FTC_Cache_Class
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*
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* <Description>
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* a structure used to describe a given cache object class to
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* the cache manager.
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*
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* <Fields>
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* cache_byte_size :: size of cache object in bytes
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* init_cache :: cache object initializer
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* done_cache :: cache object finalizer
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*/
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struct FTC_Cache_Class_
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{
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FT_UInt cache_byte_size;
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FTC_Cache_InitFunc init_cache;
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FTC_Cache_DoneFunc done_cache;
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};
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/**********************************************************************
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*
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* <Struct> FTC_CacheRec
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*
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* <Description>
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* a structure used to describe an abstract cache object
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*
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* <Fields>
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* manager :: handle to parent cache manager
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* memory :: handle to memory manager
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* clazz :: pointer to cache clazz
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* node_clazz :: pointer to cache's node clazz
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*
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* cache_index :: index of cache in manager's table
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* cache_data :: data passed to the cache node constructor/finalizer
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*/
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typedef struct FTC_CacheRec_
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{
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FTC_Manager manager;
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FT_Memory memory;
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FTC_Cache_Class* clazz;
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FTC_CacheNode_Class* node_clazz;
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FT_UInt cache_index; /* in manager's table */
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FT_Pointer cache_data; /* passed to cache node methods */
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} FTC_CacheRec;
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#ifdef __cplusplus
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}
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#endif
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#endif /* FTCMANAG_H */
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/* END */
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