6.7 System Initialization

Before you can run a C/C++ program, you must create the C/C++ run-time environment. The C/C++ boot routine performs this task using a function called c_int00 (or _c_int00). The run-time-support source library, rts.src, contains the source to this routine in a module named boot.c (or boot.asm).

To begin running the system, the c_int00 function can be called by reset hardware. You must link the c_int00 function with the other object files. This occurs automatically when you use the --rom_model or --ram_model link option and include a standard run-time-support library as one of the linker input files.

When C/C++ programs are linked, the linker sets the entry point value in the executable output file to the symbol c_int00.

The c_int00 function performs the following tasks to initialize the environment:

1. Switches to the appropriate mode, reserves space for the run-time stack, and sets up the initial value of the stack pointer (SP). The stack is not aligned on specific boundary.
2. Calls the function _ _TI_auto_init to perform the C/C++ autoinitialization.

The _ _TI_auto_init function does the following tasks:

• Processes the binit copy table, if present.
• Performs C autoinitialization of global/static variables. For more information, see Section 6.7.2.
• Calls C++ initialization routines for file scope construction from the global constructor table. For more information, see Section 6.7.2.6.
3. Calls the main() function to run the C/C++ program.

You can replace or modify the boot routine to meet your system requirements. However, the boot routine must perform the operations listed above to correctly initialize the C/C++ environment.