File Systems

There are 	SMALL and 	WIDE file systems
	BYTE:	8 bit		16 bit
	WORD:	16 bit		32 bit
	CHAR:	Latin-1		UCS-2
	MDATE: 	days 		seconds
			since 2000 	since 2000
			(179 years)	(136 years)

For the Z80 all wide words (uint32) look word-swapped.
All IDE devices are WIDE.
All I2C devices are SMALL.
Block size of all IDE devices is 512 8-bit bytes
Block size of all I2C EEproms is 16/32/64 bytes


Definitions:

RANGE:
	WORD		start			// block number of first block, 0-based
	WORD		count			// amount of consecutive blocks

DIRENTRY: directory entry for file
	BYTE		FILETYPE = 0x02 = ISAFILE
	WORD		filesize
	WORD		timestamp
	BYTE		name.count		// file name
	BYTE[]		name
	BYTE		ranges.count	// block allocation
	RANGE[] 	ranges

DIRENTRY: directory entry for directory
	BYTE		FILETYPE = 0x01 = ISADIR
	WORD		filesize
	WORD		timestamp
	BYTE		name.count
	BYTE[]		name
	WORD		block0			// block number of first block, 0-based

DIRENTRY: erased data or spare:
	BYTE[]		0x80 + num bytes to skip
				should be a series of 0x80+N ... 0x83, 0x82, 0x81, 0x80

DIRENTRY: directory end marker
	BYTE		0x7E

Directory file:
	WORD		parent			// block0 of parent directory
	BYTE		ranges.count	// allocation for the directory file itself
	RANGE[] 	ranges
	DIRENTRY[]					// Directory entries
	BYTE		0x7E 			// end marker

Root directory file, starting at block 1:
	WORD		0x0000 			// block0 of parent directory
	BYTE		ranges.count	// allocation for the root directory file itself
	RANGE[] 	ranges
	DIRENTRY[0]	".trash"		// first directory entry is for the trash directory
	DIRENTRY[…]
	BYTE		0x7E 			// end marker

Root block (block 0) on device:
	WORD		0x11C3 = 1st magic word		small: bytes = C3 11 C6 6D
	WORD		0x6DC6 = 2nd magic word		wide:  bytes = 00 00 C3 11 00 00 C6 6D
  BlockDevice info:
	BYTE		log2blocksize
	WORD		num_blocks
	BYTE		0x00 = spare
  standard directory entry for root dir:
	DIRENTRY 	root directory
	BYTE		0x7E 			// end marker



const FSMagic1 = 0x11C3		small: bytes = C3 11 C6 6D
const FSMagic2 = 0x6DC6		wide:  bytes = 00 00 C3 11 00 00 C6 6D