Texas Instruments TI89 Developer Guide - Page 174

132 Chapter 13: Memory Management 13.2. HeapGetLock HeapLock HeapMax HeapMoveHigh HeapPtrToHandle HeapRealloc HeapShuffle HeapSize HeapUnlock HLock - Return TRUE if a block is locked, otherwise return FALSE. - Lock the block referenced by the given handle so that it is NOT moved during garbage collection. - Return the maximum block allowable in the heap (does garbage collection). - Try to reallocate a block as high in memory as possible. - Find the handle to a given pointer. - Reallocate the size of a heap block (smaller or larger). - Move blocks of memory around (for debugging). - Return the number of bytes allocated for the given heap block. - Unlock the block referenced by the given handle so that it can be moved during garbage collection. - Lock and dereference a handle. File System The File routines provide a convenient way to store application data. Each active file must have an associated FILES structure. Files are stored in the symbol table (see section 13.3 Managing Variables) and as such have a semipermanent life. Filenames used as parameters are not tokenized variable names as required by the symbol table code, but are a string of characters. They must not be reserved names. If a filename does not have a folder name then it will be stored in the current folder. Internally, files are stored as third-party data types (GEN_DATA_TAG). This type is further defined by a file description which may be up to four letters. This will show up to the user in the VAR-LINK screen as the type specified when the file was opened. When a file is opened with FOpen in FM_WRITE or FM_APPEND mode the associated variable is locked and inaccessible by any other routines in the system. It must be closed with FClose to return the variable to not in-use mode, to write the file type and the GEN_DATA_TAG, and to close the associated buffer. For files opened in FM_READ mode, the FClose will merely update the mode of the file in the FILES structure to closed and clear the associated error status. TI-89 / TI-92 Plus Developer Guide Not for Distribution Beta Version January 26, 2001