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| author | Joe Tsai <joetsai@digital-static.net> | 2016-07-25 15:49:35 -0700 |
|---|---|---|
| committer | Joe Tsai <thebrokentoaster@gmail.com> | 2016-07-25 23:20:40 +0000 |
| commit | d0256118de0b397494a3f4ca6d2e1e889b8c114e (patch) | |
| tree | ea69eb757387e3712107b2e3009b815e0656a1d8 | |
| parent | 10538a8f9e2e718a47633ac5a6e90415a2c3f5f1 (diff) | |
| download | go-d0256118de0b397494a3f4ca6d2e1e889b8c114e.tar.gz go-d0256118de0b397494a3f4ca6d2e1e889b8c114e.zip | |
compress/flate: document HuffmanOnly
Fixes #16489
Change-Id: I13e2ed6de59102f977566de637d8d09b4e541980
Reviewed-on: https://go-review.googlesource.com/25200
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
| -rw-r--r-- | src/compress/flate/deflate.go | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/compress/flate/deflate.go b/src/compress/flate/deflate.go index 8a085ba347..3e4dc7b57e 100644 --- a/src/compress/flate/deflate.go +++ b/src/compress/flate/deflate.go @@ -15,7 +15,17 @@ const ( BestSpeed = 1 BestCompression = 9 DefaultCompression = -1 - HuffmanOnly = -2 // Disables match search and only does Huffman entropy reduction. + + // HuffmanOnly disables Lempel-Ziv match searching and only performs Huffman + // entropy encoding. This mode is useful in compressing data that has + // already been compressed with an LZ style algorithm (e.g. Snappy or LZ4) + // that lacks an entropy encoder. Compression gains are achieved when + // certain bytes in the input stream occur more frequently than others. + // + // Note that HuffmanOnly produces a compressed output that is + // RFC 1951 compliant. That is, any valid DEFLATE decompressor will + // continue to be able to decompress this output. + HuffmanOnly = -2 ) const ( @@ -644,7 +654,6 @@ func (d *compressor) close() error { // a very fast compression for all types of input, but sacrificing considerable // compression efficiency. // -// // If level is in the range [-2, 9] then the error returned will be nil. // Otherwise the error returned will be non-nil. func NewWriter(w io.Writer, level int) (*Writer, error) { |