From: Yann Collet <cyan@fb.com>
Date: Wed, 28 Jun 2017 20:22:37 +0000 (-0700)
Subject: adjusted compression levels to guarantee a monotonically increasing memory budget
X-Git-Tag: v1.3.0~1^2~12^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=adbe74a8ac099d9f97929478b9ba45c9fa2cdc27;p=thirdparty%2Fzstd.git

adjusted compression levels to guarantee a monotonically increasing memory budget
---

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index ea37197ff..c781232c6 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -3992,30 +3992,30 @@ size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output)
 int ZSTD_maxCLevel(void) { return ZSTD_MAX_CLEVEL; }
 
 static const ZSTD_compressionParameters ZSTD_defaultCParameters[4][ZSTD_MAX_CLEVEL+1] = {
-{   /* "default" */
+{   /* "default" - guarantees a monotonically increasing memory budget */
     /* W,  C,  H,  S,  L, TL, strat */
     { 18, 12, 12,  1,  7, 16, ZSTD_fast    },  /* level  0 - never used */
     { 19, 13, 14,  1,  7, 16, ZSTD_fast    },  /* level  1 */
     { 19, 15, 16,  1,  6, 16, ZSTD_fast    },  /* level  2 */
-    { 20, 16, 17,  1,  5, 16, ZSTD_dfast   },  /* level  3.*/
-    { 20, 18, 18,  1,  5, 16, ZSTD_dfast   },  /* level  4.*/
-    { 20, 15, 18,  3,  5, 16, ZSTD_greedy  },  /* level  5 */
-    { 21, 16, 19,  2,  5, 16, ZSTD_lazy    },  /* level  6 */
-    { 21, 17, 20,  3,  5, 16, ZSTD_lazy    },  /* level  7 */
+    { 20, 16, 17,  1,  5, 16, ZSTD_dfast   },  /* level  3 */
+    { 20, 17, 18,  1,  5, 16, ZSTD_dfast   },  /* level  4 */
+    { 20, 17, 18,  2,  5, 16, ZSTD_greedy  },  /* level  5 */
+    { 21, 17, 19,  2,  5, 16, ZSTD_lazy    },  /* level  6 */
+    { 21, 18, 19,  3,  5, 16, ZSTD_lazy    },  /* level  7 */
     { 21, 18, 20,  3,  5, 16, ZSTD_lazy2   },  /* level  8 */
-    { 21, 20, 20,  3,  5, 16, ZSTD_lazy2   },  /* level  9 */
+    { 21, 19, 20,  3,  5, 16, ZSTD_lazy2   },  /* level  9 */
     { 21, 19, 21,  4,  5, 16, ZSTD_lazy2   },  /* level 10 */
     { 22, 20, 22,  4,  5, 16, ZSTD_lazy2   },  /* level 11 */
     { 22, 20, 22,  5,  5, 16, ZSTD_lazy2   },  /* level 12 */
     { 22, 21, 22,  5,  5, 16, ZSTD_lazy2   },  /* level 13 */
     { 22, 21, 22,  6,  5, 16, ZSTD_lazy2   },  /* level 14 */
-    { 22, 21, 21,  5,  5, 16, ZSTD_btlazy2 },  /* level 15 */
+    { 22, 21, 22,  5,  5, 16, ZSTD_btlazy2 },  /* level 15 */
     { 23, 22, 22,  5,  5, 16, ZSTD_btlazy2 },  /* level 16 */
-    { 23, 21, 22,  4,  5, 24, ZSTD_btopt   },  /* level 17 */
+    { 23, 22, 22,  4,  5, 24, ZSTD_btopt   },  /* level 17 */
     { 23, 22, 22,  5,  4, 32, ZSTD_btopt   },  /* level 18 */
     { 23, 23, 22,  6,  3, 48, ZSTD_btopt   },  /* level 19 */
     { 25, 25, 23,  7,  3, 64, ZSTD_btultra },  /* level 20 */
-    { 26, 26, 23,  7,  3,256, ZSTD_btultra },  /* level 21 */
+    { 26, 26, 24,  7,  3,256, ZSTD_btultra },  /* level 21 */
     { 27, 27, 25,  9,  3,512, ZSTD_btultra },  /* level 22 */
 },
 {   /* for srcSize <= 256 KB */