xnu-7195.50.7.100.1.tar.gz

[apple/xnu.git] / libkern / zlib / inftrees.c

diff --git a/libkern/zlib/inftrees.c b/libkern/zlib/inftrees.c
index 8d4f79594c9d06e218d3b66088047b666f4f9569..c049915df1deca11e4621a11d2e07ee9cd720710 100644 (file)
--- a/libkern/zlib/inftrees.c
+++ b/libkern/zlib/inftrees.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008-2016 Apple Inc. All rights reserved.
+ * Copyright (c) 2008-2016, 2020 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
@@ -78,7 +78,7 @@ inflate_table(codetype type, unsigned short FAR *lens, unsigned codes,
     code FAR *next;             /* next available space in table */
     const unsigned short FAR *base;     /* base value table to use */
     const unsigned short FAR *extra;    /* extra bits table to use */
-    int end;                    /* use base and extra for symbol > end */
+    unsigned match;             /* use base and extra for symbol >= match */
     unsigned short count[MAXBITS+1];    /* number of codes of each length */
     unsigned short offs[MAXBITS+1];     /* offsets in table for each length */
     static const unsigned short lbase[31] = { /* Length codes 257..285 base */
@@ -206,19 +206,17 @@ inflate_table(codetype type, unsigned short FAR *lens, unsigned codes,
     switch (type) {
     case CODES:
         base = extra = work;    /* dummy value--not used */
-        end = 19;
+        match = 20;
         break;
     case LENS:
         base = lbase;
-        base -= 257;
         extra = lext;
-        extra -= 257;
-        end = 256;
+        match = 257;
         break;
     default:            /* DISTS */
         base = dbase;
         extra = dext;
-        end = -1;
+        match = 0;
     }
 
     /* initialize state for loop */
@@ -240,13 +238,13 @@ inflate_table(codetype type, unsigned short FAR *lens, unsigned codes,
     for (;;) {
         /* create table entry */
         this.bits = (unsigned char)(len - drop);
-        if ((int)(work[sym]) < end) {
+        if (work[sym] + 1 < match) {
             this.op = (unsigned char)0;
             this.val = work[sym];
         }
-        else if ((int)(work[sym]) > end) {
-            this.op = (unsigned char)(extra[work[sym]]);
-            this.val = base[work[sym]];
+        else if (work[sym] >= match) {
+            this.op = (unsigned char)(extra[work[sym] - match]);
+            this.val = base[work[sym] - match];
         }
         else {
             this.op = (unsigned char)(32 + 64);         /* end of block */