MsgReceivePulse(), MsgReceivePulse_r()

Receive a pulse on a channel

Synopsis:

#include <sys/neutrino.h>

int MsgReceivePulse( int chid,
                     void * pulse,
                     int bytes,
                     struct _msg_info * info );

int MsgReceivePulse_r( int chid,
                       void * pulse,
                       int bytes,
                       struct _msg_info * info );

Arguments:

chid
The ID of a channel that you established by calling ChannelCreate(), or -1 to dissociate the thread from the last channel it received on (see "Server boost" in the Interprocess Communication chapter of the System Architecture guide).
pulse
A void * pointer to a struct _pulse structure where the function can store the received data.
Note: If this buffer isn't big enough to contain a struct _pulse structure, you'll get an EFAULT.
bytes
The size of the buffer.
info
The function doesn't update this structure, so you typically pass NULL for this argument.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The MsgReceivePulse() and MsgReceivePulse_r() kernel calls wait for a pulse to arrive on the channel identified by chid and place the received data in the buffer pointed to by pulse. If the buffer is large enough, the number of bytes written to it is the size of a struct _pulse structure.

These functions are identical, except in the way they indicate errors; see the Returns section for details.

If a pulse is waiting on the channel when you call MsgReceivePulse(), the calling thread doesn't block, and the pulse is immediately copied. If a pulse isn't waiting, the calling thread enters the RECEIVE-blocked state until a pulse arrives.

If multiple pulses are sent to a channel without a thread waiting to receive them, the pulses are queued in priority order.

When a thread receives a pulse:

Note: Don't reply to a pulse.

Blocking states

State Meaning
STATE_RECEIVE There's no pulse waiting.

Returns:

The only difference between MsgReceivePulse() and MsgReceivePulse_r() is the way they indicate errors. On success, they both return 0.

If an error occurred:

Errors:

EFAULT
A fault occurred when the kernel tried to access the buffer provided, or the size of the receive buffer is less than the size of a struct _pulse. The pulse is lost in this case.
EINTR
The call was interrupted by a signal.
ESRCH
The channel indicated by chid doesn't exist.
ETIMEDOUT
A kernel timeout unblocked the call. See TimerTimeout().

Classification:

QNX Neutrino

Safety:  
Cancellation point Yes
Interrupt handler No
Signal handler Yes
Thread Yes