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author | Eugene Kliuchnikov <eustas@google.com> | 2019-04-12 13:57:42 +0200 |
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committer | GitHub <noreply@github.com> | 2019-04-12 13:57:42 +0200 |
commit | 4b2b2d4f83ffeaac7708e44409fe34896a01a278 (patch) | |
tree | 04dff6010a8fad91ba93eff45a8730ed5fc40f14 /c/enc/metablock.c | |
parent | 9cd01c0437e8b6010434d3491a348a5645de624b (diff) | |
download | brotli-4b2b2d4f83ffeaac7708e44409fe34896a01a278.zip brotli-4b2b2d4f83ffeaac7708e44409fe34896a01a278.tar.gz brotli-4b2b2d4f83ffeaac7708e44409fe34896a01a278.tar.bz2 |
Update (#749)
Update:
* Bazel: fix MSVC configuration
* C: common: extended documentation and helpers around distance codes
* C: common: enable BROTLI_DCHECK in "debug" builds
* C: common: fix implicit trailing zero in `kPrefixSuffix`
* C: dec: fix possible bit reader discharge for "large-window" mode
* C: dec: simplify distance decoding via lookup table
* C: dec: reuse decoder state members memory via union with lookup table
* C: dec: add decoder state diagram
* C: enc: clarify access to static dictionary
* C: enc: improve static dictionary hash
* C: enc: add "stream offset" parameter for parallel encoding
* C: enc: reorganize hasher; now Q2-Q3 require exactly 256KiB
to avoid global TCMalloc lock
* C: enc: fix rare access to uninitialized data in ring-buffer
* C: enc: reorganize logging / checks in `write_bits.h`
* Java: dec: add "large-window" support
* Java: dec: improve speed
* Java: dec: debug and 32-bit mode are now activated via system properties
* Java: dec: demystify some state variables (use better names)
* Dictionary generator: add single input mode
* Java: dec: modernize tests
* Bazel: js: pick working commit for closure rules
Diffstat (limited to 'c/enc/metablock.c')
-rw-r--r-- | c/enc/metablock.c | 28 |
1 files changed, 12 insertions, 16 deletions
diff --git a/c/enc/metablock.c b/c/enc/metablock.c index 4e80044..b3e6c38 100644 --- a/c/enc/metablock.c +++ b/c/enc/metablock.c @@ -28,34 +28,30 @@ extern "C" { void BrotliInitDistanceParams(BrotliEncoderParams* params, uint32_t npostfix, uint32_t ndirect) { BrotliDistanceParams* dist_params = ¶ms->dist; - uint32_t alphabet_size, max_distance; + uint32_t alphabet_size_max; + uint32_t alphabet_size_limit; + uint32_t max_distance; dist_params->distance_postfix_bits = npostfix; dist_params->num_direct_distance_codes = ndirect; - alphabet_size = BROTLI_DISTANCE_ALPHABET_SIZE( + alphabet_size_max = BROTLI_DISTANCE_ALPHABET_SIZE( npostfix, ndirect, BROTLI_MAX_DISTANCE_BITS); + alphabet_size_limit = alphabet_size_max; max_distance = ndirect + (1U << (BROTLI_MAX_DISTANCE_BITS + npostfix + 2)) - (1U << (npostfix + 2)); if (params->large_window) { - static const uint32_t bound[BROTLI_MAX_NPOSTFIX + 1] = {0, 4, 12, 28}; - uint32_t postfix = 1U << npostfix; - alphabet_size = BROTLI_DISTANCE_ALPHABET_SIZE( + BrotliDistanceCodeLimit limit = BrotliCalculateDistanceCodeLimit( + BROTLI_MAX_ALLOWED_DISTANCE, npostfix, ndirect); + alphabet_size_max = BROTLI_DISTANCE_ALPHABET_SIZE( npostfix, ndirect, BROTLI_LARGE_MAX_DISTANCE_BITS); - /* The maximum distance is set so that no distance symbol used can encode - a distance larger than BROTLI_MAX_ALLOWED_DISTANCE with all - its extra bits set. */ - if (ndirect < bound[npostfix]) { - max_distance = BROTLI_MAX_ALLOWED_DISTANCE - (bound[npostfix] - ndirect); - } else if (ndirect >= bound[npostfix] + postfix) { - max_distance = (3U << 29) - 4 + (ndirect - bound[npostfix]); - } else { - max_distance = BROTLI_MAX_ALLOWED_DISTANCE; - } + alphabet_size_limit = limit.max_alphabet_size; + max_distance = limit.max_distance; } - dist_params->alphabet_size = alphabet_size; + dist_params->alphabet_size_max = alphabet_size_max; + dist_params->alphabet_size_limit = alphabet_size_limit; dist_params->max_distance = max_distance; } |