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authordkf <donal.k.fellows@manchester.ac.uk>2008-12-18 10:37:43 (GMT)
committerdkf <donal.k.fellows@manchester.ac.uk>2008-12-18 10:37:43 (GMT)
commit78dc1db00a0f102b9f4d1c04ab0b1c42108bb17b (patch)
treed9c7dfd471c5b25134ea73197e1d57545ab4c6ec /doc/zlib.n
parent26c4e7b9006efa15622227a5afe5198e8d0193be (diff)
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Compressing and decompressing channel transformation support.
Note that there may be "quality-of-implementation" issues left...
Diffstat (limited to 'doc/zlib.n')
-rw-r--r--doc/zlib.n45
1 files changed, 41 insertions, 4 deletions
diff --git a/doc/zlib.n b/doc/zlib.n
index b010eb4..45bfd1d 100644
--- a/doc/zlib.n
+++ b/doc/zlib.n
@@ -4,7 +4,7 @@
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: zlib.n,v 1.4 2008/12/13 17:36:34 dkf Exp $
+'\" RCS: @(#) $Id: zlib.n,v 1.5 2008/12/18 10:37:43 dkf Exp $
'\"
.so man.macros
.TH zlib n 8.6 Tcl "Tcl Built-In Commands"
@@ -165,7 +165,45 @@ gzip-format data on \fIchannel\fR, which must be writable.
The transformation will be a decompressing transformation that reads raw
compressed data from \fIchannel\R, which must be readable.
.PP
-\fITODO: not yet implemented!\fR
+The following options may be set when creating a transformation:
+.TP
+\fB\-header\fI dictionary\fR
+.
+Passes a description of the gzip header to create, in the same format that
+\fBzlib gzip\fR understands.
+.TP
+\fB\-level\fI compressionLevel\fR
+.
+How hard to compress the data. Must be an integer from 0 (uncompressed) to 9
+(maximally compressed).
+'\".TP
+'\"\fB\-limit\fI readaheadLimit\fR
+'\".
+'\"The maximum number of bytes ahead to read.
+'\"\fITODO: not yet implemented!\fR
+.PP
+Both compressing and decompressing channel transformations add extra options
+that may be accessed through \fBchan configure\fR. These are:
+.TP
+\fB\-flush\fI type\fR
+.
+This write-only operation flushes the current state of the compressor to the
+underlying channel. It is only valid for compressing transformations. The
+\fItype\fR must be either \fBsync\fR or \fBfull\fR for a normal flush or an
+expensive flush respectively. Note that flushing degrades compression.
+.TP
+\fB\-checksum\fR
+.
+This read-only option, valid for both compressing and decompressing
+transforms, gets the current checksum for the uncompressed data that the
+compression engine has seen so far. The compression algorithm depends on what
+format is being produced or consumed.
+.TP
+\fB\-header\fR
+.
+This read-only option, only valid for decompressing transforms that are
+processing gzip-format data, returns the dictionary describing the header read
+off the data stream.
.RE
.TP
\fBzlib stream\fI mode\fR ?\fIlevel\fR?
@@ -238,9 +276,8 @@ A short-cut for
followed by
.QW "\fIstream \fBget\fR" .
.TP
-\fIstream \fBadler32\fR
+\fIstream \fBchecksum\fR
.
-'\" Change name?
Returns the checksum of the uncompressed data seen so far by this stream.
.TP
\fIstream \fBclose\fR