fs_ram.c

支持nvram盘

/*
 * RAM low-level FS driver
 */

/*** BeginHeader fs_block_init */

/* size of the block */
#ifndef FS_BLOCK_SIZE
	#define FS_BLOCK_SIZE 4096
#endif

#ifndef FS_PHYSICAL_OFFSET
	#define FS_PHYSICAL_OFFSET	0
#endif

#define FS_TEMPBUF_SIZE	512
#define FS_BUFS_PER_BLOCK	(((int)FS_BLOCK_SIZE)/FS_TEMPBUF_SIZE)

#define FS_SECTOR_SIZE FS_TEMPBUF_SIZE

int fs_block_init(long baseaddress, int num_blocks);
int fs_block_read(int block_num, int offset, char *buf, int len);
int fs_block_write(int block_num, char *buf, int len);
int fs_block_move(long to, int block, int offset, int len);
char *fs_block_pushxpc(int block_num);

/*** EndHeader */

long fs_block_baseaddress;
int fs_block_num_blocks;

/*
 * Initilize the low-level driver, starting at baseaddress,
 * with num_blocks blocks of size FS_BLOCK_SIZE
 */
nodebug
int fs_block_init(long baseaddress, int num_blocks)
{
	/* sanity check these values? */

#GLOBAL_INIT {
	fs_block_baseaddress = 0;
}
	
#ifdef FS_DEBUG_RAM
	printf("Initilizing RAM fs driver\n");
#endif

	if(0 == fs_block_baseaddress) {
		fs_block_baseaddress = xalloc(num_blocks*FS_BLOCK_SIZE);
		fs_block_num_blocks = num_blocks;
	}

	return 0;
}

/*
 * read from block_num/offset into buf/len
 * offset == number of bytes from beginning of the block
 */
nodebug
int fs_block_read(int block_num, int offset, char *buf, int len)
{
	xmem2root((void *)buf,
		(unsigned long int)(fs_block_baseaddress + (block_num * FS_BLOCK_SIZE) + offset),
		len
		);
}

/*
 * erase block number block_num
 */
nodebug
int fs_block_erase(int block_num)
{
	static const char ff = 0xff;
	static int i;

#ifdef FS_DEBUG_RAM
	printf("RAM> Erasing block <%d>\n", block_num);
#endif

	//for(i=0; i<FS_BLOCK_SIZE; i++)
		root2xmem(fs_block_baseaddress + (block_num*FS_BLOCK_SIZE),
			&ff, 1);
}

nodebug
int fs_block_move(long to, int block, int offset, int len)
{
	xmem2xmem(to,block*FS_BLOCK_SIZE + offset + fs_block_baseaddress, len);
}

/*
 * Write the given block (described in buf/len),
 * to block number block_num (always start at offset=0 in the block)
 */
nodebug
int fs_block_write(int block_num, char *buf, int len)
{
	fs_block_erase(block_num);
#ifdef FS_DEBUG_RAM
	printf("RAM> Writing block <%d>, len <%d>\n", block_num, len);
#endif
	root2xmem(fs_block_baseaddress + (block_num*FS_BLOCK_SIZE), buf,
		(len>FS_BLOCK_SIZE)?FS_BLOCK_SIZE:len);
}

/*
 *	write a sector out. (buf is a physical address, probably in xmem)
 */
nodebug
int fs_writesector(int sector, long buf, int len)
{
#ifdef FS_DEBUG_RAM
	printf("RAM> Writing sector <%d>, len <%d>\n", sector, len);
#endif
	xmem2xmem(fs_block_baseaddress + (sector*FS_TEMPBUF_SIZE), buf, len);
}

/*
 * set the XPC such that the given block is in the window, and
 * return a pointer to the beginning of the block, as accessable
 * through the xpc window.
 */
nodebug
root char *fs_block_pushxpc(int block_num)
{
	auto long addr;
	auto char newxpc;
	auto int newoffset;

	addr = fs_block_baseaddress + (((long)block_num)*FS_BLOCK_SIZE);
	newxpc = ((char)(addr >> 12) - 0xE);
	newoffset = ((int)(addr & 0xfff) + 0xE000);

#asm
	ld	hl,(sp+@SP+newxpc)
   ld	a,l
   ld	xpc,a
#endasm

	return (char *)newoffset;
}