pSOSystem System Calls - Read

pSOS+ System Calls q_receive
q_receive Requests a message from an ordinary message queue.
#include
unsigned long q_receive(
unsigned long qid, /* queue identifier */
unsigned long flags, /* queue attributes */
unsigned long timeout, /* timeout in clock ticks */
unsigned long msg_buf[4] /* message buffer */
)
Description
Arguments
Return Value
This system call enables a task or an ISR to obtain a message from an ordinary
message queue.
qid Specifies the queue ID of the target queue.
flags Specifies whether q_receive() will block waiting for a message.
flags should have one of the following values (defined in
):
Q_NOWAIT Don't wait for message.
Q_WAIT Wait for message.
timeout Specifies the timeout interval, in units of clock ticks.
msg_buf An output parameter. Contains the received message.
If the queue is non-empty, this call always returns the first message there. If the
queue is empty and the caller specified Q_NOWAIT, then q_receive() returns with
an error code. If Q_WAIT is elected, the caller will be blocked until a message is
posted to the queue, or if the timeout argument is used, until the timeout occurs
whichever happens first. If timeout is zero and Q_WAIT is selected, then
q_receive() will wait forever. The timeout argument is ignored if Q_NOWAIT is
selected.
This system call returns 0 on success or an error code on failure.
pSOSystem System Calls 1-81
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