Copyright (c) Hyperion Entertainment and contributors.

SPLT IFF File Splitting

From AmigaOS Documentation Wiki
Jump to navigation Jump to search


ASDG's File SPLiTting system

Here is the IFF SPLT Form.
It is intended to provide a way to split big files into
smaller pieces. I am developing program to read/write this
format on a variety of platforms. Currently I have Amiga
and MSDOS versions.

It could also be used to encapsulate binary files.

Also,  my  program  generates,  and  expects,  SPLT  file names of the form
"name.001",  "name.002".  This oughta be part of the specification for this
format, although such details are beyond the scope of IFF.

	Chunk types:
		INFOnnnn	Information about the data file
			total_size	Total size of original file **
			count		Total number of chunks. **
			position	Position this chunk was in original file
					This is defined bye:
					 "Seek(file, position, OFFSET_BEGINNING)"
			unit_number	Number of this chunk, from 0..(count-1)
			secs		UNIX date format, seconds since Jan 1 1970
					AmigaDOS Seconds + 252482400 == UNIX Seconds.
			bits		File mode bits...defined by AmigaDOS
			compression	Compression type for the BODY chunk
					Compression types can be different for
					each BODY chunk.
					No compression types are defined yet.
		EOF 0004
			flag	either TRUE or FALSE.
			sum	The sum of the data in this chunk
				Sum the data chunk, a byte at
				a time. For example:

					long sum = 0;
					UBYTE *p = buffer;
					for(i=0;i<length;i++) sum += *p++;

			type	Mac filetype info. As yet this is
				not clearly defined. I will further define
				this when a Mac port is done. RSN
			chars	The original filename. Do not depend on NULL
			..	The actual data for this chunk
The INFO chunk MUST appear before the BODY chunk.  Also, the NAME chunk has
to  appear  before  the BODY chunk in the first file in order to be useful.
The NAME chunk is not required.
The EOF chunk is not required except as noted below.

Note that the unit number in the INFO chunk start numbering things at
zero, but my SPLT writer writes files with names starting at 001.

**  The  totalsize  and count fields may be zero.  If this is the case then
the  file size and or chunk size could not be known ahead of time.  Readers
of  this  FORM  should  expect this.  The last file in a sequence MUST then
have  an  EOF chunk with contents of TRUE.  If a file has a true EOF chunk,
then the data section MAY be missing.  If the last file (with total_size ==
0)  did  not contain an EOF, with flag TRUE, chunk then the end of the data
file is missing.

 -- joe porkka, ASDG Inc.
 	(608) 273 6585