Texas Instruments TI89 Developer Guide - Page 181

Chapter 13: Memory Management 139 13.3.2.3. Store Look-up Path • Is the variable a system variable? These are special cases and cannot have a specified path. Many have restrictions on the domain and type of data allowed. • If a complete path is specified and that variable already exists, replace the previous contents with the new contents (after verifying all flags, data type, etc.). Otherwise, create that variable with the given value. • If there is a backslash followed by the variable name and that variable already exists in the current user folder, replace the previous contents with the new contents (after verifying all flags, data type, etc.). Otherwise, create that variable with the given value. • If there is not a path specified, check for that variable name in the current temporary folder. If it exists, replace the previous contents with the new contents (after verifying all flags, data types, etc.). • If the variable does not exist in the current temporary folder, check the current user folder. If it exists, replace the previous contents with the new contents (after verifying all flags, data types, etc.). Otherwise, create that variable in the current user folder. 13.3.2.4. HSYM VarRecall (BYTE *Var, RECALL_FLAGS Flags) VarRecall looks up a variable returning its HSYM or H_NULL if not found. VarRecall handles system variables even if they are not in the symbol table. Var is a pointer to the terminated zero of the tokenized variable name. Flags can have the following values although 0 and VR_NO_SYS_VARS are the two flags normally used. Flags 0 VR_LINK VR_FUNC_NAME VR_NO_SYS_VARS - No restrictions. - Used by link code only. - "y1(" entered, not "y1". - Do not return system variables. The recall routine returns the HSYM handle to the symbol table which remains valid until a variable in the same folder is added, deleted, or renamed. For the system variables that are not stored in the symbol table, there is one dummy symbol table entry. When a system variable not in the table is referenced, that entry will point to a copy of the desired system variable (with a tag added) and that handle will be returned. Since this one dummy entry is used for many system variables, the calling routine may have to copy the contents if it desires to have access to more than one value at a time. There is another function, HToESI, that will return a pointer of the type EStackIndex to the data type tag. TI-89 / TI-92 Plus Developer Guide Not for Distribution Beta Version January 26, 2001