SPLT IFF File Splitting

SPLT

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.

FORMnnnnSPLT 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. CHKS0004 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++;

TYPEnnnn type Mac filetype info. As yet this is not clearly defined. I will further define this when a Mac port is done. RSN NAMEnnnn chars The original filename. Do not depend on NULL termination. BODYnnnn .. 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