Detailed Description

Architecture-dependent routines declaration.

Definition in file tn_arch.h.

Functions
void	tn_arch_int_dis (void)
	Unconditionally disable system interrupts. More...

void	tn_arch_int_en (void)
	Unconditionally enable interrupts. More...

TN_UWord	tn_arch_sr_save_int_dis (void)
	Disable system interrupts and return previous value of status register, atomically. More...

void	tn_arch_sr_restore (TN_UWord sr)
	Restore previously saved status register. More...

void	_tn_arch_sys_init (TN_UWord *int_stack, unsigned int int_stack_size)
	Architecture-dependent system startup routine. More...

TN_UWord *	_tn_arch_stack_top_get (TN_UWord *stack_low_address, int stack_size)
	Should return top of the stack, which may be: More...

TN_UWord *	_tn_arch_stack_init (TN_TaskBody task_func, TN_UWord stack_top, int stack_size, void *param)
	Should put initial CPU context to the provided stack pointer for new task and return current stack pointer. More...

int	_tn_arch_inside_isr (void)
	Should return 1 if system ISR is currently running, 0 otherwise. More...

int	_tn_arch_is_int_disabled (void)
	Should return 1 if system interrupts are currently disabled, 0 otherwise. More...

void	_tn_arch_context_switch_pend (void)
	Called whenever we need to switch context from one task to another. More...

void	_tn_arch_context_switch_now_nosave (void)
	Called whenever we need to switch context to new task, but don't save current context. More...

Function Documentation

void tn_arch_int_dis ( void )

Unconditionally disable system interrupts.

Refer to the section Interrupt types for details on what is system interrupt.

void tn_arch_int_en ( void )

Unconditionally enable interrupts.

Refer to the section Interrupt types for details on what is system interrupt.

TN_UWord tn_arch_sr_save_int_dis ( void )

Disable system interrupts and return previous value of status register, atomically.

Refer to the section Interrupt types for details on what is system interrupt.

See also: tn_arch_sr_restore()

void tn_arch_sr_restore ( TN_UWord sr )

Restore previously saved status register.

Parameters

sr	status register value previously from `tn_arch_sr_save_int_dis()`

See also: tn_arch_sr_save_int_dis()

void _tn_arch_sys_init	(	TN_UWord *	int_stack,
		unsigned int	int_stack_size
	)

Architecture-dependent system startup routine.

Called from tn_sys_start().

TN_UWord* _tn_arch_stack_top_get	(	TN_UWord *	stack_low_address,
		int	stack_size
	)

Should return top of the stack, which may be:

(stack_low_address - 1)
(stack_low_address + stack_size)
(stack_low_address)
(stack_low_address + stack_size - 1)

(depending on the architecture)

Parameters

stack_low_address	Start address of the stack array.
stack_size	Size of the stack in `TN_UWord`-s, not in bytes.

TN_UWord* _tn_arch_stack_init	(	TN_TaskBody *	task_func,
		TN_UWord *	stack_top,
		int	stack_size,
		void *	param
	)

Should put initial CPU context to the provided stack pointer for new task and return current stack pointer.

When resulting context gets restored by _tn_arch_context_switch_now_nosave() or _tn_arch_context_switch_pend(), the following conditions should be met:

Interrupts are enabled;
Return address is set to tn_task_exit(), so that when task body function returns, tn_task_exit() gets automatially called;
Argument 0 contains param pointer

Parameters

task_func	Pointer to task body function.
stack_top	Top of the stack, returned by `_tn_arch_stack_top_get()`.
stack_size	Size of the stack in `TN_UWord`-s, not in bytes.
param	User-provided parameter for task body function.

Returns: current stack pointer (top of the stack)

int _tn_arch_inside_isr ( void )

Should return 1 if system ISR is currently running, 0 otherwise.

Refer to the section Interrupt types for details on what is system ISR.

int _tn_arch_is_int_disabled ( void )

Should return 1 if system interrupts are currently disabled, 0 otherwise.

Refer to the section Interrupt types for details on what is system interrupt.

void _tn_arch_context_switch_pend ( void )

Called whenever we need to switch context from one task to another.

This function typically does NOT switch context; it merely pends it, that is, it sets appropriate interrupt flag. If current level is an application level, interrupt is fired immediately, and context gets switched.

But, if it's hard or impossible on particular platform to use dedicated interrupt flag, this function may just switch the context on its own.

Preconditions:

interrupts are enabled;
tn_curr_run_task points to currently running (preempted) task;
tn_next_task_to_run points to new task to run.

Actions to perform in actual context switching routine:

save context of the preempted task to its stack;
set tn_curr_run_task to tn_next_task_to_run;
restore context of the newly activated task from its stack.

See also: tn_curr_run_task; tn_next_task_to_run

void _tn_arch_context_switch_now_nosave ( void )

Called whenever we need to switch context to new task, but don't save current context.

This happens:

At system start, inside tn_sys_start();
At task exit, inside tn_task_exit()

This function doesn't pend context switch, it switches context immediately.

Preconditions:

interrupts are disabled;
tn_next_task_to_run is already set to needed task.

Actions to perform:

set tn_curr_run_task to tn_next_task_to_run;
restore context of the newly activated task from its stack.

See also: tn_curr_run_task; tn_next_task_to_run

Detailed Description

Functions

Function Documentation