Texas Instruments TI89 Developer Guide - Page 96

54 Chapter 7: Flash Application Layout The var and func keywords describe object frame variables and functions. FDL creates macros which let you retrieve and change the values of attribute slots and call functions in method slots. These created macros require the pointer to an object frame as their first parameter. Every application has an object frame interface to the OS. The app's object frame also serves as a shared-code library interface. As a convenience, so you do not have to find the address of the app's object frame, the keywords appvar and appfunc create macros which access an app's object frame attributes given its app ID. Note: The first parameter of a func declaration must be type pFrame, the first parameter of an appfunc declaration must be type AppID. The slot-number is an optional decimal (0 - 4294967295) or hexadecimal (0x0 - 0xFFFFFFFF) number which identifies the slot which the variable or method occupies. Subsequent slot-numbers are automatically incremented unless a new value is supplied. Since attribute slots are 32-bit values, types should declare values which fit in 32-bits, integers and pointers. Note: Functions which return nothing may declare a return type of void. The FDL compiler accepts one command line parameter, the name of the file to compile. It outputs a file of the same name with a .h extension. The output file contains C macros for accessing object frame attributes and calling frame methods. The resulting header file is suitable to include in your C source file. Here is the actual header output file after running the FDL compiler on fileio.fdl in section 7.3.3.1. Creating the Library Interface. /* FILE: CREATED: INPUT: GENERATOR: */ fileio.h 2000.04.13 09:10 fileio.fdl Frame Description Language compiler, version 2.000 /* int * PlayerFileTableCount */ #define OO_PLAYER_FILE_TABLE_COUNT (65536) – #define GetPlayerFileTableCount(obj) \ — (int *)OO_GetAppAttr(obj,65536) #define SetPlayerFileTableCount(obj,value) \ ˜ OO_SetAppAttr(obj,65536,(void *)value) TI-89 / TI-92 Plus Developer Guide Not for Distribution Beta Version January 26, 2001