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| author | Mark Adler <madler@alumni.caltech.edu> | 2016-11-05 08:43:29 -0700 |
|---|---|---|
| committer | Hans Kristian Rosbach <hk-git@circlestorm.org> | 2017-02-06 12:40:06 +0100 |
| commit | 40039a039c26da37cdc972aa650a9ea40e310f20 (patch) | |
| tree | 63d5bbdfcc02adfca7dfe1c357fe1b67a2e826b1 /deflate_p.h | |
| parent | e84a42f7a34c7f8728d669a747d149907ec9818c (diff) | |
Speed up deflation for level 0 (storing).
The previous code slid the window and the hash table and copied
every input byte three times in order to just write the data as
stored blocks with no compression. This commit minimizes sliding
and copying, especially for large input and output buffers.
Level 0 compression is now more than 20 times faster than before
the commit.
Most of the speedup is due to deferring hash table slides until
deflateParams() is called to change the compression level away
from 0. More speedup is due to copying directly from next_in to
next_out when the amounts of available input data and output space
permit it, avoiding the intermediate pending buffer. Additionally,
only the last 32K of the used input data is copied back to the
sliding window when large input buffers are provided.
Diffstat (limited to 'deflate_p.h')
| -rw-r--r-- | deflate_p.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/deflate_p.h b/deflate_p.h index 67dc6eb..6c9957a 100644 --- a/deflate_p.h +++ b/deflate_p.h @@ -80,4 +80,10 @@ static inline Pos insert_string(deflate_state *const s, const Pos str, uInt coun if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \ } +/* Maximum stored block length in deflate format (not including header). */ +#define MAX_STORED 65535 + +/* Minimum of a and b. */ +#define MIN(a, b) ((a) > (b) ? (b) : (a)) + #endif |