FILTER-DEFLATE(2) FILTER-DEFLATE(2)
NAME
deflate, inflate - data compression filters
SYNOPSIS
include "filter.m";
deflate := load Filter Filter->DEFLATEPATH;
inflate := load Filter Filter->INFLATEPATH;
init: fn();
start: fn(param: string): chan of ref Rq;
DESCRIPTION
These implementation modules conform to the Filter module
interface for data-processing filters. For details of the
interface, see filter(2).
Deflate implements gzip-compatible stream compression. The
param string argument to start can contain one or more of
the following option characters:
`d' Enable debugging output. Each line of debug-
ging output is provided in an Rq.Info mes-
sage.
`v' Enable verbose mode. Each line of verbose
output is provided in an Rq.Info message.
`h' Add a gzip header and footer to the data.
With this flag, the data after filtering will
be in exactly the same format as a gzip file,
with accompanying checksum.
`z' Add a zlib header and footer to the data.
The footer contains a checksum.
`0' to `9'
Specifies the level of compression to be used
(9 highest). See gzip(1).
Inflate performs the inverse operation to deflate. If the
param argument to start begins with the character `h' then
the input to the filter is assumed to be in the standard
gzip file format; if it starts with the character `z' it is
assumed to be in zlib format; the output will be checked for
integrity in both cases. While processing a gzip stream, the
Rq.Info message is used to transmit some information; the
type of information is determined by the first word of msg,
as follows:
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FILTER-DEFLATE(2) FILTER-DEFLATE(2)
file The rest of msg (after a following space) is the
name of the original filename before compression.
mtime
The rest of msg (after a following space) is the
modification time of the original file before com-
pression.
SOURCE
/appl/lib/deflate.b
/appl/lib/inflate.b
SEE ALSO
gzip(1), filter(2)
Internet RFCs RFC1950, RFC1951, and RFC1952.
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