root/messaging.c

DEFINITIONS

1. SendMessage
2. ReceiveMessage
3. AllocMessagePort
4. SendReceiveMessage

#include "kstructs.h"
#include "memory.h"

extern struct Task *currentTask;

void *AllocKMem(long);

//=================================
// Send a message to a message port
//=================================
void SendMessage(struct MessagePort *MP, struct Message *Msg)
{
   struct Message *temp = (struct Message *)AllocKMem(sizeof(struct Message));

   copyMem((unsigned char *)Msg, (unsigned char *)temp, sizeof(struct Message));
   temp->pid = currentTask->pid;
   if (MP->msgQueue == 0)
   {
      MP->msgQueue = temp;
   }
   else
   {
      struct Message *pMsg = MP->msgQueue;
      while (pMsg->nextMessage != 0)
      {
         pMsg = pMsg->nextMessage;
      }
      pMsg->nextMessage = temp;
   }
   if (MP->waitingProc != (struct Task *)-1L)
   {
      struct Task *task = MP->waitingProc;
      MP->waitingProc = (struct Task *)-1L;
      task->waiting   = 0;
      UnBlockTask(task);
      SWTASKS15;
   }
}


//======================================
// Receive a message from a message port
//======================================
void ReceiveMessage(struct MessagePort *MP, struct Message *Msg)
{
   while (MP->msgQueue == 0)
   {
      MP->waitingProc      = currentTask;
      currentTask->waiting = 0x80;
      BlockTask(currentTask);
      SWTASKS;
   }
   struct Message *temp = MP->msgQueue;
   MP->msgQueue = temp->nextMessage;
   copyMem((unsigned char *)temp, (unsigned char *)Msg, sizeof(struct Message));
   DeallocMem(temp);
}


//========================
// Allocate a message port
//========================
struct MessagePort *AllocMessagePort()
{
   struct MessagePort *temp = AllocKMem(sizeof(struct MessagePort));

   temp->waitingProc = (struct Task *)-1L;
   temp->msgQueue    = 0;
   return(temp);
}


//======================================================
// Send a message to a message port and wait for a reply
//======================================================
void SendReceiveMessage(struct MessagePort *MP, struct Message *Msg)
{
   struct MessagePort *tempMP = AllocMessagePort();

   Msg->tempPort = (long)tempMP;
   SendMessage(MP, Msg);
   ReceiveMessage(tempMP, Msg);
   DeallocMem(tempMP);
}