Texas Instruments TI89 Developer Guide - Page 80

38 Chapter 7: Flash Application Layout 7.3. 7.3.1. RAM ACB .data .bss .text FRAME .const Flash ROM Figure 7.2: Application RAM and Flash Usage The OS expects the first variable in the application's initialized data (.data section) to be a pointer to the app frame. The OS must be able to find the app frame in order to get the app's event processor entry point. To make this happen, you must declare a variable of type pFrame in your C source and initialize it with the address of your application's frame. Furthermore, you need to make sure it is the first initialized variable in your application. Source Layout An AMS application can serve several purposes. It can have an interactive user interface through windows and the keyboard - the most common usage. It can extend TI-BASIC with a library of functions and programs. It can implement a shared-code library - routines which can be called from other applications. And, it can override tables in the OS or another application to provide local language customization. An app can provide a mix of any of these features. This section looks at the source requirements your application needs to implement each of these features. Interactive Applications Interactive applications need an object frame and an event handler. The object frame provides a directory of attributes and methods in the application and serves as an interface to the OS. It is in the object frame that the OS finds the address of the app's event handler. This section covers the layout of the object frame with the help of FRAME, ATTR, and ENDFRAME macros, how the OS finds the app's frame, and details of predefined frame attributes and methods. Finally, a simple example pulls the pieces together into a complete application. TI-89 / TI-92 Plus Developer Guide Not for Distribution Beta Version January 26, 2001