Threads

Thread functions. More...

Functions
syscall	chprio (tid_typ tid, int newprio)
tid_typ	create (void *procaddr, uint ssize, int priority, const char *name, int nargs,...)
tid_typ	getfirst (qid_typ q)
tid_typ	getlast (qid_typ q)
tid_typ	getitem (tid_typ tid)
syscall	getprio (tid_typ tid)
tid_typ	gettid (void)
int	insert (tid_typ tid, qid_typ q, int key)
int	insertd (tid_typ tid, qid_typ q, int key)
syscall	kill (tid_typ tid)
qid_typ	queinit (void)
tid_typ	enqueue (tid_typ tid, qid_typ q)
tid_typ	dequeue (qid_typ q)
int	ready (tid_typ tid, bool resch, uint core)
message	receive (void)
message	recvclr (void)
message	recvtime (int maxwait)
int	resched (void)
syscall	resume (tid_typ tid)
syscall	send (tid_typ tid, message msg)
syscall	sleep (uint ms)
syscall	suspend (tid_typ tid)
syscall	unsleep (tid_typ tid)
void	userret (void)
syscall	yield (void)

Detailed Description

Thread functions.

Function Documentation

syscall chprio	(	tid_typ	tid,
		int	newprio
	)

Change the scheduling priority of a thread

Parameters

tid	target thread
newprio	new priority

Returns

old priority of thread

tid_typ create	(	void *	procaddr,
		uint	ssize,
		int	priority,
		const char *	name,
		int	nargs,
			...
	)

Create a thread to start running a procedure.

Parameters

procaddr	procedure address
ssize	stack size in bytes
priority	thread priority (0 is lowest priority)
name	name of the thread, used for debugging
nargs	number of arguments that follow
...	arguments to pass to thread procedure

Returns

the new thread's thread id, or ::SYSERR if a new thread could not be created (not enough memory or thread entries).

tid_typ dequeue

(

qid_typ

q

)

Remove and return the first thread on a list

Parameters

q	target queue

Returns

thread id of removed thread, or EMPTY

tid_typ enqueue	(	tid_typ	tid,
		qid_typ	q
	)

Insert a thread at the tail of a queue

Parameters

tid	thread ID to enqueue
q	target queue

Returns

thread id of enqueued thread

tid_typ getfirst

(

qid_typ

q

)

Remove a thread from front of queue

Parameters

q	target queue

Returns

thread ID of removed thread

tid_typ getitem

(

tid_typ

tid

)

Remove a thread from anywhere in a queue

Parameters

tid	thread ID to get

Returns

thread ID of removed thread

tid_typ getlast

(

qid_typ

q

)

Remove a thread from end of queue

Parameters

q	target queue

Returns

thread ID of removed thread

syscall getprio

(

tid_typ

tid

)

Return the scheduling priority of a thread

Parameters

tid

thread ID

Returns

priority of thread on success, SYSERR on failure

tid_typ gettid

(

void

)

Get the thread id of currently executing thread.

Returns

thread id of the currently running thread

int insert	(	tid_typ	tid,
		qid_typ	q,
		int	key
	)

Insert a thread into a queue in descending key order.

Parameters

tid	thread ID to insert
q	target queue
key	sorting key

Returns

OK

int insertd	(	tid_typ	tid,
		qid_typ	q,
		int	key
	)

Insert a thread in delta queue in ascending order

Parameters

tid	thread id to insert
q	queue in which thread should be inserted
key	delta key

Returns

OK

syscall kill

(

tid_typ

tid

)

Kill a thread and remove it from the system

Parameters

tid	target thread

Returns

OK on success, SYSERR otherwise

qid_typ queinit

(

void

)

Initialize a new queue in the global thread queue table

Returns

newly allocated queue ID or SYSERR

< next available quetab entry

int ready	(	tid_typ	tid,
		bool	resch,
		uint	core
	)

Make a thread eligible for CPU service.

Parameters

tid	target thread
resch	if RESCHED_YES, reschedules

Returns

OK if thread has been added to readylist, else SYSERR

message receive

(

void

)

receive - wait for a message and return it

Returns

message

message recvclr

(

void

)

Clear messages, return waiting message (if any)

Returns

msg if available, NOMSG if no message

message recvtime

(

int

maxwait

)

wait to receive a message or timeout and return result

Parameters

maxwait

ticks to wait before timeout

Returns

msg if becomes available, TIMEOUT if no message

int resched

(

void

)

Reschedule processor to highest priority ready thread. Upon entry, thrcurrent gives current thread id. Threadtab[thrcurrent].pstate gives correct NEXT state for current thread if other than THRREADY.

Returns

OK when the thread is context switched back

syscall resume

(

tid_typ

tid

)

Unsuspend a thread, making it ready

Parameters

tid	target thread

Returns

priority

syscall send	(	tid_typ	tid,
		message	msg
	)

Send a message to another thread

Parameters

tid	thread id of recipient
msg	contents of message

Returns

OK on success, SYSERR on failure

syscall sleep

(

uint

ms

)

Yields the processor for the specified number of milliseconds, allowing other threads to be scheduled.

Parameters

ms	number of milliseconds to sleep

Returns

If successful, the thread will sleep for the specified number of milliseconds, then return ::OK. Otherwise, ::SYSERR will be returned. If a system timer is not supported, ::SYSERR will always returned.

syscall suspend

(

tid_typ

tid

)

Suspend a thread, placing it in hibernation

Parameters

tid	target thread

Returns

priority or SYSERR

syscall unsleep

(

tid_typ

tid

)

Remove thread from the sleep queue prematurely

Parameters

tid	target thread

Returns

OK if thread removed, else SYSERR

void userret

(

void

)

Entered when a thread exits by return.

syscall yield

(

void

)

Yield processor.

Returns

OK when the thread is context switched back