From: Yann Collet <cyan@fb.com>
Date: Tue, 13 Feb 2018 18:02:25 +0000 (-0800)
Subject: added code comment on how to generate default tables
X-Git-Tag: v1.3.4~1^2~58^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2524cbd8475add0c962f4e7ab0f5fd9eb5b30085;p=thirdparty%2Fzstd.git

added code comment on how to generate default tables

as suggested by @terrelln
---

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index d65dd5fd9..36dfc6376 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -667,6 +667,15 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
     }
 }
 
+/* Default FSE distribution tables.
+ * These are pre-calculated FSE decoding tables using default distributions as defined in specification :
+ * https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#default-distributions
+ * They were generated programmatically with following method :
+ * - start from default distributions, present in /lib/common/zstd_internal.h
+ * - generate tables normally, using ZSTD_buildFSETable()
+ * - printout the content of tables
+ * - pretify output, report below, test with fuzzer to ensure it's correct */
+
 /* Default FSE distribution table for Literal Lengths */
 static const ZSTD_seqSymbol LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = {
      {  1,  1,  1, LL_DEFAULTNORMLOG},  /* header : fastMode, tableLog */