// vfs.c
// Author: Josh Holtrop
// Created: 12/31/03
// Modified: 01/04/04


void	vfs_init()
{
	firstDiskDevice = malloc(sizeof(DiskDevice));
	firstDiskDevice->type = VFS_DISK_FD;
	firstDiskDevice->fileSystem = VFS_FS_FAT12;
	firstDiskDevice->location = VFS_LOC_FD0;
	firstDiskDevice->link = 0;
	strcpy(firstDiskDevice->id, "fd0");
	rootDevice = firstDiskDevice;
	if (*(byte *)0xC0090000)			// the user chose to load an initial ram disk from the floppy
	{
		DiskDevice *rd = malloc(sizeof(DiskDevice));
		firstDiskDevice->link = (dword)rd;
		rd->type = VFS_DISK_RD;
		rd->fileSystem = VFS_FS_FAT12;
		rd->location = 0xC0200000;
		rd->link = 0;
		strcpy(rd->id, "rd0");
		rootDevice = rd;
	}
}


byte *vfs_readFile(char *fileName)
{
	DiskDevice *dd;
	dword	fileStartPosition;
	if (fileName[0] == '/')
	{
		dd = rootDevice;
		fileStartPosition = 1;
	}
	else
	{
		if (strlen(fileName) < 5)	//not a long enough file name
			return 0;
		if (!((fileName[3] == ':') && (fileName[4] == '/')))	//if we aren't using the root directory, then there must be a 3 character device explicitly specified
			return 0;					// followed by a colon and then a slash
		char device[4];
		memcpy(device, fileName, 3);	//copy the 3 digit device id to device
		device[3] = 0;			//null-terminating character for device string
		dd = vfs_getDiskDeviceByID(device);
		if (!dd)			//the specified device was not found
			return 0;
		fileStartPosition = 5;
	}
	switch (dd->fileSystem)
	{
	case VFS_FS_FAT12:
		return fat12_readFile(fileName+fileStartPosition, dd);
	}
	return 0;
}


byte *vfs_readSector(DiskDevice *dd, dword sector, byte *dest, dword sectors)
{
	byte	*origDest = dest;
	switch (dd->type)
	{
	case VFS_DISK_RD:
		for (; sectors > 0; sectors--, dest += 512, sector++)
			rd_readSector(dd, sector, dest);
		return origDest;
	}
	return 0;
}


DiskDevice *vfs_getDiskDeviceByID(char *id)
{
	DiskDevice *dd = firstDiskDevice;
	for (;;)
	{
		if (strcmp(dd->id, id))
			return dd;
		dd = (DiskDevice *)dd->link;
		if (!dd)
			break;
	}
	return 0;
}