newgrf_storage.h

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00001 /* $Id$ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
00006  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
00007  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
00008  */
00009 
00012 #ifndef NEWGRF_STORAGE_H
00013 #define NEWGRF_STORAGE_H
00014 
00015 #include "core/alloc_func.hpp"
00016 
00021 struct BaseStorageArray
00022 {
00024   virtual ~BaseStorageArray() {}
00025 
00033   virtual void ClearChanges(bool keep_changes) = 0;
00034 
00040   virtual void Store(uint pos, int32 value) = 0;
00041 };
00042 
00049 template <typename TYPE, uint SIZE>
00050 struct PersistentStorageArray : BaseStorageArray {
00051   TYPE storage[SIZE]; 
00052   TYPE *prev_storage; 
00053 
00055   PersistentStorageArray() : prev_storage(NULL)
00056   {
00057     memset(this->storage, 0, sizeof(this->storage));
00058   }
00059 
00061   ~PersistentStorageArray()
00062   {
00063     free(this->prev_storage);
00064   }
00065 
00073   void Store(uint pos, int32 value)
00074   {
00075     /* Out of the scope of the array */
00076     if (pos >= SIZE) return;
00077 
00078     /* The value hasn't changed, so we pretend nothing happened.
00079      * Saves a few cycles and such and it's pretty easy to check. */
00080     if (this->storage[pos] == value) return;
00081 
00082     /* We do not have made a backup; lets do so */
00083     if (this->prev_storage != NULL) {
00084       this->prev_storage = MallocT<TYPE>(SIZE);
00085       memcpy(this->prev_storage, this->storage, sizeof(this->storage));
00086 
00087       /* We only need to register ourselves when we made the backup
00088        * as that is the only time something will have changed */
00089       AddChangedStorage(this);
00090     }
00091 
00092     this->storage[pos] = value;
00093   }
00094 
00100   TYPE Get(uint pos) const
00101   {
00102     /* Out of the scope of the array */
00103     if (pos >= SIZE) return 0;
00104 
00105     return this->storage[pos];
00106   }
00107 
00112   void ClearChanges(bool keep_changes)
00113   {
00114     assert(this->prev_storage != NULL);
00115 
00116     if (!keep_changes) {
00117       memcpy(this->storage, this->prev_storage, sizeof(this->storage));
00118     }
00119     free(this->prev_storage);
00120   }
00121 };
00122 
00123 
00130 template <typename TYPE, uint SIZE>
00131 struct TemporaryStorageArray : BaseStorageArray {
00132   TYPE storage[SIZE]; 
00133 
00135   TemporaryStorageArray()
00136   {
00137     memset(this->storage, 0, sizeof(this->storage));
00138   }
00139 
00145   void Store(uint pos, int32 value)
00146   {
00147     /* Out of the scope of the array */
00148     if (pos >= SIZE) return;
00149 
00150     this->storage[pos] = value;
00151     AddChangedStorage(this);
00152   }
00153 
00159   TYPE Get(uint pos) const
00160   {
00161     /* Out of the scope of the array */
00162     if (pos >= SIZE) return 0;
00163 
00164     return this->storage[pos];
00165   }
00166 
00167   void ClearChanges(bool keep_changes)
00168   {
00169     memset(this->storage, 0, sizeof(this->storage));
00170   }
00171 };
00172 
00173 void AddChangedStorage(BaseStorageArray *storage);
00174 void ClearStorageChanges(bool keep_changes);
00175 
00176 #endif /* NEWGRF_STORAGE_H */

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