root/messaging.c

DEFINITIONS

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

#include "kernel.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 *)ALLOCMSG;

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

//======================================
// 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;
    }
    asm("cli");
    struct Message *temp = MP->msgQueue;
    MP->msgQueue = temp->nextMessage;
    temp->nextMessage = 0;
    asm("sti");
    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);
}