T-Kernel Specification (1.B0.02)

138 CHAPTER 4. T-KERNEL/OS FUNCTIONS
tk fwd por
Forward Rendezvous to Other Port
[C Language Interface]
ER ercd = tk_fwd_por ( ID porid, UINT calptn, RNO rdvno, VP msg, INT cmsgsz ) ;
[Parameters]
ID porid Rendezvous port ID
UINT calptn Call bit pattern (indicating conditions of the caller)
RNO rdvno Rendezvous number before forwarding
VP msg Message packet address
INT cmsgsz Call message size (in bytes)
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
E PAR
E OBJ
E CTX
E DISWAI
Normal completion
Invalid ID number (porid is invalid or cannot be used, or porid is a rendezvous port of
another node)
Object does not exist (the rendezvous port designated in porid does not exist)
Parameter error (cmsgsz < 0, cmsgsz > maxcmsz after forwarding, cmsgsz > maxrmsz
before forwarding, calptn = 0, or value that cannot be used in msg)
Invalid object state (rdvno is invalid, or maxrmsz (after forwarding) > maxrmsz (before
forwarding))
Context error (issued from task-independent portion (implementation-dependent error))
Wait released by wait disabled state
[Description]
Forwards an accepted rendezvous to another rendezvous port.
The task issuing this system call (here “Task X”) must have accepted the rendezvous designated in
porid; i.e., this system call can be issued only after executing tk acp por. In the discussion that follows,
the rendezvous calling task is “Task Y”, and the rendezvous number passed in a return parameter by
tk acp por is rdvno. After tk fwd por is issued in this situation, the rendezvous between Task X and
Task Y is released, and all processing thereafter is the same as if Task Y had called for a rendezvous on
another port (rendezvous port B) passed to this system call in porid.
The specific operations of tk fwd por are as follows.
1. The rendezvous designated in rdvno is released.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02