T-Kernel Specification (1.B0.02)

4.3. TASK EXCEPTION HANDLING FUNCTIONS 71
void texhdr( INT texcd )
{
/*
Task exception handling
*/
}
/* Task exception handler termination */
if ( texcd == 0 ) {
tk_ext_tsk() or tk_exd_tsk();
} else {
tk_end_tex();
return or longjmp();
}
A task exception handler behaves only like a TA ASM attribute object and cannot be called via a high-level
language support routine. The entry part of the task exception handler must be written in assembly
language. The OS vendor must provide the assembly language source of the entry routine for calling
the above C language task exception handler. That is, source code equivalent to a high-level language
support routine must be provided.
A task set to protection level TA RNG0 when it is created cannot use task exceptions.
[Additional Notes]
At the time a task is created, no task exception handler is defined and task exceptions are disabled.
When a task reverts to DORMANT state, the task exception handler definition is canceled and task
exceptions are disabled. Pending task exceptions are cleared. It is possible, however, to define a task
exception handler for a task in DORMANT state.
Task exceptions are software interrupts raised by tk ras tex, with no direct relation to CPU exceptions.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02