pm3_tmp.c

小型操作系统,以VC为开发环境,需要boachs调试

/***************************************************************************
**     File name   : pm3_tmp.c
**     Author      : x.cheng
**     Create date :
**
**	   Comment:
**        内存分页管理模块中负责对内核空间的临时空间进行分页管理
**		临时空间是内核本身未使用的，但是内核在进行其他的管理工作时会使用到
**		的临时映射数据的保留空间，比方说在创建进程的虚拟空间时使用。
**
**     Revisions:
**     $Log: pm3_tmp.c,v $
**     Revision 1.1.1.1  2005/07/27 06:53:15  x.cheng
**     add into repositories
**
**
***************************************************************************/
#include "const.h"
#include "type.h"
#include "stdarg.h"


#include "..\..\Inc\i386\system.h"
#include "..\..\Inc\i386\page.h"
#include "..\..\Inc\i386\map.h"
#include "..\..\Inc\i386\mmx.h"
#include "..\..\Inc\spinlock.h"
#include "..\..\inc\tui.h"
#define __PMM_SRC__
#include "..\inc\def_pmm.h"


//! Spinlock for mutual exclusion of temporary pages.
DECLARE_SPINLOCK( stTemporaryMemoryLock );

/************************************************************
*************************************************************
**      Function Name:			pvPm3GetOneFreeTmpPage()
**      Author:                 x.cheng
**
**      Comment:
**			Get a free virtual page from the temporary memory area.
**
**      List of parameters:
**			no
**
**      Return value:   
**			The address of the temporary page or NULL if out of memory.
**
**      Revisions:
** 
*************************************************************
*************************************************************/
void *pvPm3GetOneFreeTmpPage()
{
	unsigned char *pucTmpPage = (unsigned char*)KERNEL_TEMP_START_ADDRESS;
	unsigned long ulPfn;
	unsigned long ulFlags;

	SpinlockDisableIrqAndLock(&stTemporaryMemoryLock, ulFlags);

	while ( 1 ) {
		if ( *pulAddressToPde( (unsigned long)pucTmpPage ) ) {
			if ( *pulAddressToPte( (unsigned long)pucTmpPage ) ) {
				pucTmpPage += PAGE_SIZE;
				if ( pucTmpPage >= (unsigned char*)KERNEL_TEMP_END_ADDRESS ) {
					//out of temporary memory
					SpinlockEnableIrqAndUnlock(&stTemporaryMemoryLock, ulFlags);
					return NULL;
				}
				continue;
			}
		}
		// OK! A free temporary page has been found!
		// Now map this page to a free frame and return the
		// virtual address of this page, or NULL if there is
		// no free frame.
		ulPfn = ulPm2GetOneFreePage();
		if ( NULL == ulPfn ) {
			pucTmpPage = NULL;
		} else if ( !ulPm2MapPageToVirtualAddress( ulPfn, (unsigned long)pucTmpPage, P_PRESENT | P_WRITE) ) {
			pucTmpPage = NULL;
		}

		SpinlockEnableIrqAndUnlock(&stTemporaryMemoryLock, ulFlags);
		return ( (void *)pucTmpPage );
	}
}

/************************************************************
*************************************************************
**      Function Name:			vPm3FreeOneTmpPage()
**      Author:                 x.cheng
**
**      Comment:
**			Free a virtual temporary page allocated by pvPm3GetOneFreeTmpPage.
**
**      List of parameters:
**			void * - the temporary page virtual address
**			bool
**				TRUE - free the page and also the physical frame
**				FALSE - unmapp the page only, do not free the physical frame.
**
**      Return value:   
**			none.
**
**      Revisions:
**			bool类型定义在type.h中，是int
*************************************************************
*************************************************************/
void vPm3FreeOneTmpPage(void *pvTmpPage, bool bFreeFrame)
{
	unsigned long ulFlags;

	SpinlockDisableIrqAndLock(&stTemporaryMemoryLock, ulFlags);

	// is the page into the temporary memory range?!
	if ( ((unsigned long)pvTmpPage >= KERNEL_TEMP_START_ADDRESS) && 
		((unsigned long)pvTmpPage < KERNEL_TEMP_END_ADDRESS) ) {
		if ( TRUE == bFreeFrame ) {
			//delete_page( (uint32_t)p );
		} else {
			//unmap_page( (uint32_t)p );
		}
	}

	SpinlockEnableIrqAndUnlock(&stTemporaryMemoryLock, ulFlags);
}