kthread.cpp

小型的操作系统开发的原代码

//***********************************************************************/
//    Author                    : Garry
//    Original Date             : Jun,28 2004
//    Module Name               : kthread.h
//    Module Funciton           : 
//                                This module countains kernal thread
//                                implementation code.
//    Last modified Author      :
//    Last modified Date        :
//    Last modified Content     :
//                                1.
//                                2.
//    Lines number              :
//***********************************************************************/

#ifndef __STDAFX_H__
#include "..\INCLUDE\StdAfx.h"
#endif

//
//The following two global variables are used to control the 
//kernal threads.
//Once create a kernal thread,the creat rountine will add a entry
//to the __KTHREAD_CONTROL_BLOCK* array,and make the proper
//g_bKThreadQueueStatus index to 1.
//Once delete a kernal thread,onle set the g_bKThreadQueueStatus's
//indexed value to 0.
//
__KTHREAD_CONTROL_BLOCK*  g_pKThreadQueue[MAX_KTHREAD_NUM]        = {0};
BYTE                      g_bKThreadQueueStatus[MAX_KTHREAD_NUM]  = {0};

//
//The kernal thread queue pointers.
//The system maintaince some kernal thread queues,including:
//1. Ready queue,countains the kernal thread ready to run;
//2. Blocked queue,countains the blocked kernal thread;
//3. Running queue,countains the current running kernal threads;
//4. Dead queue,countains the dead kernal thread;
//5. Suspend queue,countains the suspended kernal thread.
//
static __KTHREAD_CONTROL_BLOCK*  g_pReadyQueue     = NULL;
static __KTHREAD_CONTROL_BLOCK*  g_pBlockedQueue   = NULL;
static __KTHREAD_CONTROL_BLOCK*  g_pRunningQueue   = NULL;
static __KTHREAD_CONTROL_BLOCK*  g_pDeadQueue      = NULL;
static __KTHREAD_CONTROL_BLOCK*  g_pSuspendQueue   = NULL;

//
//The current running kernal thread's ID.
//
static DWORD  g_dwCurrentKThreadID = 1;

//
//Message queue operations.
//

//If message queue is full.
BOOL KtMsgQueueFull(__KTHREAD_CONTROL_BLOCK* pControlBlock)
{
	if(NULL == pControlBlock)  //Parameter check.
		return FALSE;

	return MAX_KTHREAD_MSG_NUM == pControlBlock->wCurrentMsgNum ? TRUE : FALSE;
}

//If message queue empty.
BOOL KtMsgQueueEmpty(__KTHREAD_CONTROL_BLOCK* pControlBlock)
{
	if(NULL == pControlBlock)
		return FALSE;

	return 0 == pControlBlock->wCurrentMsgNum ? TRUE : FALSE;
}

//Add a message to the current kernal thread's message queue.
BOOL KtSendMessage(__KTHREAD_CONTROL_BLOCK* pControlBlock,
				   __KTHREAD_MSG*           pMsg)
{
	BOOL           bResult = FALSE;

	if((NULL == pControlBlock) || (NULL == pMsg)) //Parameters check.
		return bResult;

	if(KtMsgQueueFull(pControlBlock))             //If the queue is full.
		return bResult;

	//DisableInterrupt();                           //The following operation should not be
	                                              //interrupted.
	pControlBlock->ktmsg[pControlBlock->wTrial].wCommand    = pMsg->wCommand;
	pControlBlock->ktmsg[pControlBlock->wTrial].dwParam_01  = pMsg->dwParam_01;
	pControlBlock->ktmsg[pControlBlock->wTrial].dwParam_02  = pMsg->dwParam_02;

	pControlBlock->wTrial ++;
	if(MAX_KTHREAD_MSG_NUM == pControlBlock->wTrial)
		pControlBlock->wTrial = 0x0000;
	pControlBlock->wCurrentMsgNum ++;
	bResult = TRUE;
	
	//EnableInterrupt();                            //Enable interrupts.

	return bResult;
}

//Get a message from current kernal thread's message queue and delete it from the queue.
BOOL KtGetMessage(__KTHREAD_CONTROL_BLOCK* pControlBlock,
				  __KTHREAD_MSG*           pMsg)
{
	if((NULL == pControlBlock) || (NULL == pMsg))  //Parameters check.
		return FALSE;

	if(KtMsgQueueEmpty(pControlBlock))
		return FALSE;

	//DisableInterrupt();
	pMsg->wCommand     = pControlBlock->ktmsg[pControlBlock->wHeader].wCommand;
	pMsg->dwParam_01   = pControlBlock->ktmsg[pControlBlock->wHeader].dwParam_01;
	pMsg->dwParam_02   = pControlBlock->ktmsg[pControlBlock->wHeader].dwParam_02;

	pControlBlock->wHeader ++;
	if(MAX_KTHREAD_MSG_NUM == pControlBlock->wHeader)
		pControlBlock->wHeader = 0x0000;
	pControlBlock->wCurrentMsgNum --;
	//EnableInterrupt();                    //Enable the interrupt.

	return TRUE;
}

BOOL KtDispatchMessage(__KTHREAD_MSG* pMsg,
						__KTHREAD_MSG_HANDLER    msghdr)
{
	if((NULL == pMsg) || (NULL == msghdr))
		return FALSE;

	return msghdr(pMsg->wCommand,pMsg->dwParam_01,pMsg->dwParam_01);
}

//
//Global functions implementation.
//

DWORD  GetCurrentKThreadID()
{
	return g_dwCurrentKThreadID;
}

//
//Create a thread,and put the thread's control block into array g_pKThreadQueue,
//and update the corresponding queue.
//If failed,it returns 0,otherwise,returns the created kernal thread's ID.
//
DWORD CreateKThread(DWORD             dwStackSize,      //Thread's stack size.
					DWORD             dwFlags,          //Flags.
					DWORD             dwPriority,       //Priority.
					LPKTHREAD_ROUTINE pStartAddress,    //Start running address.
					LPVOID            pData,            //Parameter.
					LPVOID            /*pReserved*/)        //Reserved.
{
	DWORD                    dwKThreadID      = 0x00000000;
	__KTHREAD_CONTROL_BLOCK* pControlBlock    = NULL;
	LPVOID                   pStackPointer    = NULL;
	BOOL                     bFind            = FALSE;
	
	RoundTo4k(dwStackSize);               //Round the stack size to 4k times.
	pControlBlock = (__KTHREAD_CONTROL_BLOCK*)KMemAlloc(dwStackSize,KMEM_SIZE_TYPE_4K);
	if(NULL == pControlBlock)             //If can not allocate the memory.
	{
		return dwKThreadID;
	}
	MemZero((LPVOID)pControlBlock,dwStackSize);    //Zero the memory allocated just now.

	pControlBlock->pKThreadRoutine      =  pStartAddress;  //Members initialization.
	pControlBlock->dwKThreadPriority    =  dwPriority;
	pControlBlock->pData                =  pData;
	pControlBlock->wCurrentMsgNum       =  0x0000;
	pControlBlock->wHeader              =  0x0000;
	pControlBlock->wTrial               =  0x0000;

	//DisableInterrupt();                   //Disable interrupt.
	                                      // ****************
	for(dwKThreadID = 0;dwKThreadID < MAX_KTHREAD_NUM;dwKThreadID ++)
	{
		if(0 == g_bKThreadQueueStatus[dwKThreadID])  //Find a free control block slot.
		{
			bFind = TRUE;
			break;
		}
	}

	if(FALSE == bFind)                    //If can not find a free control block slot.
	{
		KMemFree((LPVOID)pControlBlock,KMEM_SIZE_TYPE_4K,dwStackSize);  //Free the memory.
		return 0L;
	}
	
	DisableInterrupt();                   //Disable interrupt.
	                                      //******************
	g_pKThreadQueue[dwKThreadID]  = pControlBlock;
	g_bKThreadQueueStatus[dwKThreadID] = 1;          //Set the occupied flag.
	dwKThreadID ++;                       //Increase the KThreadID.
	pControlBlock->dwKThreadID  = dwKThreadID;
	pControlBlock->dwStackSize  = dwStackSize;

	switch(dwFlags)                      //Update the proper kernal thread queues.
		                                 //Insert the created kernal thread into
										 //the status queue.
	{
	case KTHREAD_STATUS_BLOCKED:         //Insert into blocked queue.
		pControlBlock->dwKThreadStatus = KTHREAD_STATUS_BLOCKED;
		pControlBlock->pNext = g_pBlockedQueue;
		g_pBlockedQueue = pControlBlock;
		break;
	case KTHREAD_STATUS_SUSPEND:         //Insert it into suspended queue.
		pControlBlock->dwKThreadStatus = KTHREAD_STATUS_SUSPEND;
		pControlBlock->pNext = g_pSuspendQueue;
		g_pSuspendQueue = pControlBlock;
		break;
	default:                             //All other status,insert into ready queue.
	case KTHREAD_STATUS_READY:
	case KTHREAD_STATUS_RUNNING:
		pControlBlock->dwKThreadStatus = KTHREAD_STATUS_READY;
		pControlBlock->pNext = g_pReadyQueue;
		g_pReadyQueue = pControlBlock;
		break;
	}

#ifdef __I386__                           //Update the x86 CPU's context.
	pControlBlock->dwESP = (DWORD)pControlBlock + dwStackSize;
	pControlBlock->dwEIP = (DWORD)pStartAddress;
	pControlBlock->dwEFlags = 512;        //*****************************
#else
#endif
	EnableInterrupt();                    //Enable interrupt.
	                                      //*****************
	return dwKThreadID;
}

//