Compress Trace Files

Filename

compress-trace.p4m

Description

All the programs that access trace files can uncompress on-the-fly. This module maybe used to compress existing trace files files. No compression programs are supplied with the package, although there are several good public domain compression programs available.

Option: Compression method

This selects the algorithm used for compressing SCF files. The choices are None, Compress (the standard UNIX compression program), Gzip (from GNU) and Bzip versions 1 and 2. These are listed in ascending order of compression ratios, with Bzip (either version) giving the best compression. Generally Gzip is the best supported program and is not too far behind Bzip. The following table provides comparisons with compression sizes on ABI and SCF files. (Note that the ABI file typically holds 12 bit trace data data.) The sizes listed are the average length, in bytes, of the 25 (originally ABI) files that the tests were performed on.

File type               Size in bytes
abi                     185193
compressed abi          138040
gzipped abi             105009
bzipped abi             78203
16-bit scf              90121
compress 16-bit scf     27692
gzipped 16-bit scf      27595
bzipped 16-bit scf      18950
8-bit scf               50100
compress 8-bit scf      14888
gzipped 8-bit scf       14742
bzipped 8-bit scf       11819