xnu-7195.101.1.tar.gz

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

diff --git a/libkern/zlib/inftrees.c b/libkern/zlib/inftrees.c
index 338c455c860326ea037f0ab92d33011137f77fa6..c049915df1deca11e4621a11d2e07ee9cd720710 100644 (file)
--- a/libkern/zlib/inftrees.c
+++ b/libkern/zlib/inftrees.c
@@ -1,8 +1,8 @@
 /*
- * Copyright (c) 2008 Apple Inc. All rights reserved.
+ * Copyright (c) 2008-2016, 2020 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
- * 
+ *
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
@@ -11,10 +11,10 @@
  * unlawful or unlicensed copies of an Apple operating system, or to
  * circumvent, violate, or enable the circumvention or violation of, any
  * terms of an Apple operating system software license agreement.
- * 
+ *
  * Please obtain a copy of the License at
  * http://www.opensource.apple.com/apsl/ and read it before using this file.
- * 
+ *
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
@@ -22,7 +22,7 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
- * 
+ *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /* inftrees.c -- generate Huffman trees for efficient decoding
@@ -56,13 +56,10 @@ const char inflate_copyright[] =
    table index bits.  It will differ if the request is greater than the
    longest code or if it is less than the shortest code.
  */
-int inflate_table(type, lens, codes, table, bits, work)
-codetype type;
-unsigned short FAR *lens;
-unsigned codes;
-code FAR * FAR *table;
-unsigned FAR *bits;
-unsigned short FAR *work;
+int
+inflate_table(codetype type, unsigned short FAR *lens, unsigned codes,
+             code FAR * FAR *table, unsigned FAR *bits,
+             unsigned short FAR *work)
 {
     unsigned len;               /* a code's length in bits */
     unsigned sym;               /* index of code symbols */
@@ -81,7 +78,7 @@ unsigned short FAR *work;
     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 */
@@ -209,19 +206,17 @@ unsigned short FAR *work;
     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 */
@@ -243,13 +238,13 @@ unsigned short FAR *work;
     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 */