/*
 * MailBoy.c - Handles all of the messages between processes.
 *
 * By: Theo Van Dinter - 96/09/09
 *
 * I called this 'mailboy' since these set of functions handle mail delivery.
 *
 */

#include "mailbox.h" /* Mr. Standard Header */

/*
 * SendMsg - 96/09/09
 *
 * By: Theo Van Dinter (felicity@kluge.net)
 *
 * Send a message to a mailbox.
 *
 * Parameters: iTo  = Mailbox to send to
 *             pMsg = Pointer to message structure
 *
 * Returns -1 on error, 0 if success.
 *
 */
int SendMsg(int iTo, struct msg *pMsg)
{
  if (swait(semid[2*iTo])==-1) /* Wait to send message */
    return(-1);
  if (pMsg!=(struct msg *)NULL) /* Assuming we didn't get a NULL message to
				   send, copy the values into the mailbox
				   message */
    {
      inbox[iTo]->iFrom=pMsg->iFrom;
      inbox[iTo]->wType=pMsg->wType;
      inbox[iTo]->wVal1=pMsg->wVal1;
      inbox[iTo]->wVal2=pMsg->wVal2;
      inbox[iTo]->wTotal=pMsg->wTotal;
    }
  if (ssignal(semid[2*iTo+1])==-1) /* Signal any message receivers */
    return(-1);

  return(0);
}

/*
 * RecvMsg - 96/09/09
 *
 * By: Theo Van Dinter (felicity@kluge.net)
 *
 * Returns the message from a mailbox.
 *
 * Parameters: iFrom = Mailbox to retrieve the message from.
 *             pMsg  = Point to message structure.
 *
 * Returns -1 on error, 0 if success.
 *
 */
int RecvMsg(int iFrom, struct msg *pMsg)
{
  if (swait(semid[2*iFrom+1])==-1) /* Wait for a message */
    return(-1);
  if (pMsg!=(struct msg *)NULL) /* We can't receive into a NULL structure.
				   Otherwise, copy the mailbox message into
				   the message structure */
    {
      pMsg->iFrom=inbox[iFrom]->iFrom;
      pMsg->wType=inbox[iFrom]->wType;
      pMsg->wVal1=inbox[iFrom]->wVal1;
      pMsg->wVal2=inbox[iFrom]->wVal2;
      pMsg->wTotal=inbox[iFrom]->wTotal;
    }
  if (ssignal(semid[2*iFrom])==-1) /* Signal any message senders */
    return(-1);
  return(0);
}