RTEMS 4.6.0pre5 On-Line Library

Eventflags Manager twai_flg - Wait on Eventflag with Timeout

RTEMS ITRON 3.0 API User's Guide

4.4.7: twai_flg - Wait on Eventflag with Timeout

CALLING SEQUENCE:

ER twai_flg(
  UINT *p_flgptn,
  ID flgid,
  UINT waiptn,
  UINT wfmode,
  TMO tmout
);

STATUS CODES:

E_OK - Normal Completion

E_ID - Invalid ID number (flgid was invalid or could not be used)

E_NOEXS - Object does not exist (the eventflag specified by flgid does not exist)

E_OACV - Object access violation (A flgid less than -4 was specified from a user task. This is implementation dependent.)

E_PAR - Parameter error (waiptn = 0, wfmode invalid, or tmout is -2 or less)

E_OBJ - Invalid object state (multiple tasks waiting for an eventflag with the TA_WSGL attribute)

E_DLT - The object being waited for was deleted (the specified eventflag was deleted while waiting)

E_RLWAI - WAIT state was forcibly released (rel_wai was received while waiting)

E_TMOUT - Polling failure or timeout exceeded

E_CTX - Context error (issued from task-independent portions or a task in dispatch disabled state)

EN_OBJNO - An object number which could not be accessed on the target node is specified.

EN_PAR - A value outside the range supported by the target node and/or transmission packet format was specified as a parameter (a value outside supported range was specified for waiptn and tmout)

EN_RPAR - A value outside the range supported by the requesting node and/or transmission packet format was specified as a parameter (a value exceeding the range for the requesting node was specified for flgptn)

DESCRIPTION:

The twai_flg system call has the same function as wai_flg with an additional timeout feature. A maximum wait time (timeout value) can be specified using the parameter tmout. When a timeout is specified, a timeout error, E_TMOUT, will result and the system call will finish if the period specified by tmout elapses without conditions for releasing wait being satisfied.

Specifying TMO_POL = 0 to twai_flg for tmout indicates that a timeout value of 0 be used, resulting in exactly the same processing as pol_flg. Specifying TMO_FEVR = -1 to twai_flg for tmout indicates that an infinite timeout value be used, resulting in exactly the same processing as wai_flg.

NOTES:

Multiprocessing is not supported. Thus none of the "EN_" status codes will be returned.

Pol_flg and wai_flg represent the same processing as specifying certain values (TMO_POL or TMO_FEVR) to twai_flg for tmout. As such, only twai_flg is implemented in the kernel; pol_flg and wai_flg should be implemented as macros which call twai_flg.

RTEMS ITRON 3.0 API User's Guide