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| author | Alexey Ivanov <SaveTheRbtz@GMail.com> | 2018-10-02 07:28:37 -0700 |
|---|---|---|
| committer | Eugene Kliuchnikov <eustas@google.com> | 2018-10-02 16:28:37 +0200 |
| commit | c94c6f805c881b2a67540f5953a59d963d87a7f8 (patch) | |
| tree | 631703e7f946341e6c68d577ad47e80feaa64c65 | |
| parent | 9402ac5c08806f4ba400bc390420c29ddd78ecd1 (diff) | |
| download | brotli-c94c6f805c881b2a67540f5953a59d963d87a7f8.zip brotli-c94c6f805c881b2a67540f5953a59d963d87a7f8.tar.gz brotli-c94c6f805c881b2a67540f5953a59d963d87a7f8.tar.bz2 | |
tools/brotli: improve window size autodetect (#710)
Window size is defined as:
`(1 << BROTLI_PARAM_LGWIN) - 16`
in `c/include/brotli/encode.h`
Therefore we should probably take these 16 bytes into account.
Done basic manual testing:
$ python3 -c 'print ("A"*2046)' > t
$ bazel run -- //:brotli -w 0 -f -o $(realpath t).br $(realpath ./t)
$ python3 research/brotlidump.py t.br |& fgrep WSIZE
0000 c1 1000001 WSIZE windowsize=(1<<12)-16=4080
New version properly detects window size of `4080`, while previous one used `2032`:
$ python3 research/brotlidump.py t.br |& fgrep WSIZE
0000 b1 0110001 WSIZE windowsize=(1<<11)-16=2032
| -rw-r--r-- | c/tools/brotli.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/c/tools/brotli.c b/c/tools/brotli.c index ea4fdac..ce05b64 100644 --- a/c/tools/brotli.c +++ b/c/tools/brotli.c @@ -943,10 +943,9 @@ static BROTLI_BOOL CompressFiles(Context* context) { uint32_t lgwin = DEFAULT_LGWIN; /* Use file size to limit lgwin. */ if (context->input_file_length >= 0) { - int32_t size = 1 << BROTLI_MIN_WINDOW_BITS; lgwin = BROTLI_MIN_WINDOW_BITS; - while (size < context->input_file_length) { - size <<= 1; + while (BROTLI_MAX_BACKWARD_LIMIT(lgwin) < + (uint64_t)context->input_file_length) { lgwin++; if (lgwin == BROTLI_MAX_WINDOW_BITS) break; } |