基于RAM的文件系统的实现

如果的系统上安装有硬盘，则在BSP中装载你的硬盘驱动即可。如果没有，建议建立基于RAM的文件系统。建立RAM文件系统的方式如下：


#ifndef RAMDISK_VERSION
#define RAMDISK_VERSION "1.0 built by tiefeng@vip.sina.com"
#endif // RAMDISK_VERSION

#include
#include
#include
#include
#include
#include


/**********************************************************************

Function: Create a ram disk device
Parameters:
name -> device name, such as "ramdisk0:".
size -> block device size.
Returned:
The actualy disk size. or ERROR.

**********************************************************************/

STATUS CreateRamDisk(char * name,int size)
{
int nBlock = NULL ;
BLK_DEV * pBlkDev = NULL ;
DOS_VOL_DESC * pVolDesc = NULL ;

// the disksize should be integral multiple of the blocksize.

size = size - sizeQ2 ;
nBlock = size/512 ;

// You can simultaneously open 20 files

dosFsInit(20) ;

// Create a ram-disk.
// The base address is the return value of alloc.
// The block size is 512.
// nBlock blocks per track
// Total nBlock blocks.
// The base address offset is 0.

pBlkDev = ramDevCreate(0,512,nBlock,nBlock,0) ;
if (NULL==pBlkDev)
{
fprintf(stderr,"Can not create ram block device.\n") ;
return ERRor ;
}

// Make DOSFS by a ram block device.

pVolDesc = dosFsMkfs(name,pBlkDev) ;
if (NULL==pVolDesc)
{
fprintf(stderr,"Can not create ram-dos-fs.\n") ;
return ERRor ;
}

// The size is actualy disk size.

return size ;
}

/**********************************************************************

Function: Delete a ram disk device
Parameters:
name -> device name, such as "ramdisk0:".
Returned:
Return OK if the device is removed successfuly.
Otherwise return ERROR.

**********************************************************************/

STATUS DeleteRamDisk(char * name)
{
DEV_HDR * pDevHdr = NULL ;

// Find ram-disk device by name

if ( NULL==(pDevHdr="iosDevFind"(name,NULL)) )
{
fprintf(stderr,"Can not find device (%s).\n",name) ;
return ERRor ;
}

// Delete the device and free the alloced memory

iosDevDelete(pDevHdr) ;
free(pDevHdr) ;

return OK ;
}

/**********************************************************************

Function: Create a ram disk device & set is as default path.
Parameters:
name -> device name, such as "ramdisk0:".
size -> block device size.
Returned:
The actualy disk size. or ERROR.

**********************************************************************/

STATUS InitRamFsEnv(char * name,int size)
{
STATUS iReturn = CreateRamDisk(name,size) ;

if (ERROR!=iReturn) ioDefPathSet(name) ;

return iReturn ;
}