Protothreads

Modules
	Local continuations
	Local continuations form the basis for implementing protothreads.
	Protothread semaphores
	This module implements counting semaphores on top of protothreads.

Files
file	pt.h
	Protothreads implementation.

Macros
#define	PT_ENDED   3
#define	PT_EXITED   2
#define	PT_WAITING   0
#define	PT_YIELDED   1

Initialization
#define	PT_INIT(pt)
	Initialize a protothread. More...

Declaration and definition
#define	PT_THREAD(name_args)
	Declaration of a protothread. More...
#define	PT_BEGIN(pt)
	Declare the start of a protothread inside the C function implementing the protothread. More...
#define	PT_END(pt)
	Declare the end of a protothread. More...

Blocked wait
#define	PT_WAIT_UNTIL(pt, condition)
	Block and wait until condition is true. More...
#define	PT_WAIT_WHILE(pt, cond)
	Block and wait while condition is true. More...

Hierarchical protothreads
#define	PT_WAIT_THREAD(pt, thread)
	Block and wait until a child protothread completes. More...
#define	PT_SPAWN(pt, child, thread)
	Spawn a child protothread and wait until it exits. More...

Exiting and restarting
#define	PT_RESTART(pt)
	Restart the protothread. More...
#define	PT_EXIT(pt)
	Exit the protothread. More...

Calling a protothread
#define	PT_SCHEDULE(f)
	Schedule a protothread. More...

Yielding from a protothread
#define	PT_YIELD(pt)
	Yield from the current protothread. More...
#define	PT_YIELD_UNTIL(pt, cond)
	Yield from the protothread until a condition occurs. More...

Detailed Description

Macro Definition Documentation

PT_BEGIN

#define PT_BEGIN

(

pt

)

Declare the start of a protothread inside the C function implementing the protothread.

This macro is used to declare the starting point of a protothread. It should be placed at the start of the function in which the protothread runs. All C statements above the PT_BEGIN() invokation will be executed each time the protothread is scheduled.

Parameters

pt	A pointer to the protothread control structure.

PT_END

#define PT_END

(

pt

)

Declare the end of a protothread.

This macro is used for declaring that a protothread ends. It must always be used together with a matching PT_BEGIN() macro.

Parameters

pt	A pointer to the protothread control structure.

PT_EXIT

#define PT_EXIT

(

pt

)

Exit the protothread.

This macro causes the protothread to exit. If the protothread was spawned by another protothread, the parent protothread will become unblocked and can continue to run.

Parameters

pt	A pointer to the protothread control structure.

PT_INIT

#define PT_INIT

(

pt

)

Initialize a protothread.

Initializes a protothread. Initialization must be done prior to starting to execute the protothread.

Parameters

pt	A pointer to the protothread control structure.

See also

PT_SPAWN()

PT_RESTART

#define PT_RESTART

(

pt

)

Restart the protothread.

This macro will block and cause the running protothread to restart its execution at the place of the PT_BEGIN() call.

Parameters

pt	A pointer to the protothread control structure.

PT_SCHEDULE

#define PT_SCHEDULE

(

f

)

Schedule a protothread.

This function schedules a protothread. The return value of the function is non-zero if the protothread is running or zero if the protothread has exited.

Parameters

f	The call to the C function implementing the protothread to be scheduled

PT_SPAWN

#define PT_SPAWN	(		pt,
			child,
			thread
	)

Spawn a child protothread and wait until it exits.

This macro spawns a child protothread and waits until it exits. The macro can only be used within a protothread.

Parameters

pt	A pointer to the protothread control structure.
child	A pointer to the child protothread's control structure.
thread	The child protothread with arguments

PT_THREAD

#define PT_THREAD

(

name_args

)

Declaration of a protothread.

This macro is used to declare a protothread. All protothreads must be declared with this macro.

Parameters

name_args

The name and arguments of the C function implementing the protothread.

PT_WAIT_THREAD

#define PT_WAIT_THREAD	(		pt,
			thread
	)

Block and wait until a child protothread completes.

This macro schedules a child protothread. The current protothread will block until the child protothread completes.

Note

The child protothread must be manually initialized with the PT_INIT() function before this function is used.

Parameters

pt	A pointer to the protothread control structure.
thread	The child protothread with arguments

See also

PT_SPAWN()

PT_WAIT_UNTIL

#define PT_WAIT_UNTIL	(		pt,
			condition
	)

Block and wait until condition is true.

This macro blocks the protothread until the specified condition is true.

Parameters

pt	A pointer to the protothread control structure.
condition	The condition.

PT_WAIT_WHILE

#define PT_WAIT_WHILE	(		pt,
			cond
	)

Block and wait while condition is true.

This function blocks and waits while condition is true. See PT_WAIT_UNTIL().

Parameters

pt	A pointer to the protothread control structure.
cond	The condition.

PT_YIELD

#define PT_YIELD

(

pt

)

Yield from the current protothread.

This function will yield the protothread, thereby allowing other processing to take place in the system.

Parameters

pt	A pointer to the protothread control structure.

PT_YIELD_UNTIL

#define PT_YIELD_UNTIL	(		pt,
			cond
	)

Yield from the protothread until a condition occurs.

Parameters

pt	A pointer to the protothread control structure.
cond	The condition. This function will yield the protothread, until the specified condition evaluates to true.