Category : C Source Code
Archive   : AETSK101.ZIP
Filename : MAILBOX.CC

/**********************************************************************
*
* NAME: mailbox.cpp
*
* DESCRIPTION: class MBox (mailbox) implementation
*
* copyright (c) 1991 J. Alan Eldridge
*
* M O D I F I C A T I O N H I S T O R Y
*
* when who what
* -------------------------------------------------------------------
* 05/09/91 J. Alan Eldridge broke out of task.cpp
*
* 11/14/91 jae now class MBoxBase member functions
* are here, and the constructors for
* MBox & MBoxPri are inline in task.h
*
*********************************************************************/

#include "aedef.h"
#include "task.h"

//------------------------------------------------------------
// ********** CLASS MBOX MEMBER FUNCTIONS **********
//------------------------------------------------------------

//------------------------------------------------------------
// MBoxBase::send() -- wait for box to be free, then put msg
// NOTE: sender doesn't return until message is picked up
//------------------------------------------------------------

int
MBoxBase::send(void *msg, int n, clock_t msec)
{
if (!s_send->wait(msec))
return 0;
m_len = n;
m_msg = msg;
s_recv->signal(0);
return s_pickup.wait();
}

//------------------------------------------------------------
// MBoxBase::recv() -- wait for a message, then retrieve it
// and wake up the sender... return -1 if timed out, otherwise
// return length of data
//------------------------------------------------------------

int
MBoxBase::recv(void *msg, clock_t msec)
{
int len;

if (!s_recv->wait(msec))
return 0;
memcpy(msg, m_msg, len = m_len);
s_send->signal(0);
s_pickup.signal();
return len;
}