From: Dougall Johnson <dougallj@gmail.com>
Date: Mon, 22 Aug 2022 00:57:39 +0000 (+1000)
Subject: Inflate: Increase max root table sizes to 10 and 9
X-Git-Tag: 2.1.0-beta1~166
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2d110b17b815016b5419592b7484ae9affb6fe68;p=thirdparty%2Fzlib-ng.git

Inflate: Increase max root table sizes to 10 and 9

This increases the size of the `codes` array by 1920 bytes (33%), but
improves performance a little. Root table size is still limited by the
maximum code length in use, so tiny files typically see no change to
table-building time, as they don't use longer codes.
---

diff --git a/infback.c b/infback.c
index 200997c4..f56db8e8 100644
--- a/infback.c
+++ b/infback.c
@@ -329,18 +329,18 @@ int32_t Z_EXPORT PREFIX(inflateBack)(PREFIX3(stream) *strm, in_func in, void *in
             }
 
             /* build code tables -- note: do not change the lenbits or distbits
-               values here (9 and 6) without reading the comments in inftrees.h
+               values here (10 and 9) without reading the comments in inftrees.h
                concerning the ENOUGH constants, which depend on those values */
             state->next = state->codes;
             state->lencode = (const code *)(state->next);
-            state->lenbits = 9;
+            state->lenbits = 10;
             ret = zng_inflate_table(LENS, state->lens, state->nlen, &(state->next), &(state->lenbits), state->work);
             if (ret) {
                 SET_BAD("invalid literal/lengths set");
                 break;
             }
             state->distcode = (const code *)(state->next);
-            state->distbits = 6;
+            state->distbits = 9;
             ret = zng_inflate_table(DISTS, state->lens + state->nlen, state->ndist,
                                 &(state->next), &(state->distbits), state->work);
             if (ret) {
diff --git a/inflate.c b/inflate.c
index 6085fffa..e109182f 100644
--- a/inflate.c
+++ b/inflate.c
@@ -820,18 +820,18 @@ int32_t Z_EXPORT PREFIX(inflate)(PREFIX3(stream) *strm, int32_t flush) {
             }
 
             /* build code tables -- note: do not change the lenbits or distbits
-               values here (9 and 6) without reading the comments in inftrees.h
+               values here (10 and 9) without reading the comments in inftrees.h
                concerning the ENOUGH constants, which depend on those values */
             state->next = state->codes;
             state->lencode = (const code *)(state->next);
-            state->lenbits = 9;
+            state->lenbits = 10;
             ret = zng_inflate_table(LENS, state->lens, state->nlen, &(state->next), &(state->lenbits), state->work);
             if (ret) {
                 SET_BAD("invalid literal/lengths set");
                 break;
             }
             state->distcode = (const code *)(state->next);
-            state->distbits = 6;
+            state->distbits = 9;
             ret = zng_inflate_table(DISTS, state->lens + state->nlen, state->ndist,
                             &(state->next), &(state->distbits), state->work);
             if (ret) {
diff --git a/inftrees.h b/inftrees.h
index bb6274a1..eeae9c6a 100644
--- a/inftrees.h
+++ b/inftrees.h
@@ -39,17 +39,17 @@ typedef struct {
  */
 
 /* Maximum size of the dynamic table.  The maximum number of code structures is
-   1444, which is the sum of 852 for literal/length codes and 592 for distance
+   1924, which is the sum of 1332 for literal/length codes and 592 for distance
    codes.  These values were found by exhaustive searches using the program
    examples/enough.c found in the zlib distributions.  The arguments to that
    program are the number of symbols, the initial root table size, and the
-   maximum bit length of a code.  "enough 286 9 15" for literal/length codes
-   returns returns 852, and "enough 30 6 15" for distance codes returns 592.
-   The initial root table size (9 or 6) is found in the fifth argument of the
+   maximum bit length of a code.  "enough 286 10 15" for literal/length codes
+   returns returns 1332, and "enough 30 9 15" for distance codes returns 592.
+   The initial root table size (10 or 9) is found in the fifth argument of the
    inflate_table() calls in inflate.c and infback.c.  If the root table size is
    changed, then these maximum sizes would be need to be recalculated and
    updated. */
-#define ENOUGH_LENS 852
+#define ENOUGH_LENS 1332
 #define ENOUGH_DISTS 592
 #define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)