Notes On Programming - Fujitsu F2MC-16L User Manual

CHAPTER 1 Notes on Operation
1.1

Notes on Programming

Describes important points on programming for Softune REALOS/907.
I Notes on programming
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Do not call ext_tsk from task independent portions.
Calling ext_tsk from a task independent portion generates an error and enters an
infinite loop on returning to the task independent portion.
Do not call ret_int from task portions.
The previous context may not be able to be restored if ret_int is called from a task
portion.
Call ext_tsk to terminate a task.
Tasks do not terminate on the ret_int or return instructions (such as the retp and ret
assembler instructions or the C language return statement). The program will not
function correctly if these instructions are used instead of calling ext_tsk.
Do not write directly to the following registers and memory areas from within user
programs.
Special registers (PS, SSB, SSP, USB, USP), register memory banks used by the
kernel (between 190H and 19fH in the general-purpose register area), delayed
interrupt control register, interrupt control register, interrupt vector table, and OS data
area.
These areas are used by the kernel.
The user does not need to create a program containing the interrupt vector table and
OS initial data. These are generated as programs by the configurator during system
configuration.
After a reset, system calls cannot be used before execution of the OS entry routine.
The first system call that can be used after the completion of OS initialization is the
initialize handler routine.
The initialize handler routine can only use system calls that can be used in task
independent portions. The initialize handler program must specify use of memory
areas other than the memory register bank used by the kernel.
As message passing using the mailboxes is performed by passing pointers, there must
be a one-to-one relationship between send and receive operations.
The message header area is used when passing messages using the mailboxes.
Therefore, do not write to the message header after sending the message.
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